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 204-1

Copyright © 2020 National Fire Protection A�sociation®. All Rights Reserved.

Standard for

Smoke and Heat Venting

2021 Edition

This edition of NFPA 204, Standa·rdfar Smoke and Heat Venting, was prepared by the Technical
Committee on Smoke Management Systems. It was issued by the Standards Council on October 5,
2020, with an effective date of October 25, 2020, and supet·sedes all previous editions.
This edition of NFPA 204 was approved as an American National Standard on October 25, 2020.

Origin and Development ofNFPA 204

This prqject was initiated in 1956 when the NFPA Boat·d of Directors t·efened the subject to the
Committee on Building Construction. A tentative guide was submitted to NFPA in 1958. Revised and
tentatively adopted in 1959 and again in 1960, the guide was officially adopted in 1961. In 1968, a
revised edition was adopted that included a new section, Inspection and Maintenance.
In 1975, a reconfirmation action failed as concerns over use of the guide in cor�junction with
automatic sprinklered buildings surfaced. Because of this controversy, work on a revision to the
guide continued at a slow pace.
The Technical Committee and Subcommittee members agreed that the state of the art had
progressed sufficiently to develop improved technology-based criteria for design of venting;
therefot·e, the 1982 edition of the document represented a major advance in engineered smoke and
heating venting, although reservations over vent and sprinkler applications still existed.
At the time the guide was formulated, the current venting theory was considered unwieldy for this
format; consequently, the more adaptable theory as described herein was adopted.
Appreciation must be extended to Dr. Gunnar Heskestad at the Factory Mutual Research
Corporation (now FM Global) for his major contribution to the theory applied in this standard,
which is detailed in Annex B.
The 1985 edition again revised Chapter 6 on the sul�ect of venring in sprinklered buildings. Test
data from work done at the Illinois Institute of Technology Research, which had been submitted to
the committee as part of a public proposal, did not permit consensus to be developed on whethet·
sprinkler control was impaired or enhanced by d1e presence of automatic roof vents of typical
spacing and area. The revised wording of Chapter 6 encouraged the designer to use the available
tools and data t·efet·enced in the document while the use of automatic venting in sprinklered
buildings was under review.
The 1991 edition made minor changes to Chapter 6 to acknowledge that a design basis existed for
using sprinklers and automatic heat venting together but that such had not received wide
recognition.
The 1998 edition represented a complete revision of the guide. The rewrite deleted the previous
tables that listed vent areas and incorporated engineering equations and referenced computet·
models, such as LAVENT and DETACT, to provide the designer with the necessary tools to develop
vent designs based on performance objectives. This rewrite was based extensively on state-of�the-art
technology published in the references. In many cases, the authors of these references participated
in the task group's re\vrite efforts.
For the 2002 edition ofNFPA 204, the document was converted from a guide to a standard, thus
implementing mandatory requirements and updated language. The document was also updated to
meet Manual ofStyle far NFPA 'Jechnical Cammittee Documents requirements.

NFPA and National Fire Protection Association are registered trademarks of the National Fire Protection Association, Quincy, Massachusetts 02169.
204-2 SMOKE AND HEAT VENTING

The 2007 edition included a number of technical changes. New provisions on air entrainment into the fire plume, the
effect of wind on the location of air vents, sizing of air paths, air velocity limitations, and plugholing were pmvided.
In addition, information on the use of vents as air inlets and a better description of the smoke layer interface were added.
Revisions with regard to how heat release rates, discharge coefficients, exhaust rates, and the number of exhaust inlets are to
be determined were incorporated. Reference to international standards on vents, mechanical smoke exu·act, and draft
curtains, as well as updated am1ex text on recent research efforts, were provided.
The 2012 edition was updated to include additional requirements and annex material for venting in sprinklered buildings.
The 2015 edition included revised provisions on draft curtains. These requirements created consistency with NFPA 92.
The 2018 edition was updated to include a correction to an Annex A image, the addition of a definition for the term
standaTd, and updated references.
For the 2021 edition, all references in Chapters 5 and 6 that permit spt·inkler waterflow to activate automatic smoke vents
have been removed. In addition, SI unit conversions have been added to Annex C, and references have been updated.

2021 Edition
 COMMITIEE PERSONNEL 204-3

Technical Committee on Smoke Management Systems

Allyn J. Vaughn, Chair
Las Vegas, NV [SE]

Elyahu Avidor, Tel Aviv, Israel [RT] William E. Koffel, Koffel Associates, Inc., MD [M]
Rep. Standards lnstirut.ion oflsrael Rep. AAMA Smoke Vent Task Group
Carl F. Baldassarra, Wiss Janney Elst.ner Associates, Inc., IL [SE] Jeffrey A. Maddox, The Fire Consultants, Inc., CA [SE]

Jonathan Cantwell, Reedy Creek Improvement District, FL [E] CameronJ. McCartney, National Research Council of Canada,
Kelly Charles, City of San Diego, CA [E] Canada [RT]

Flora F. Chen, Hayward Fire Department, California, CA [E] James A. Milke, University of Maryland, MD [SE]

Alberto Cusimano, Dupont International SA, Switzerland [U] ThomasJ. Parrish, Telgian Corporation, Ml [M]
Rep. Automatic Fire Alarm Association, Inc.
RichardJ. Davis, FM Global, lVIA [I]
Joseph Plati, Code Consultants, Inc., NY [SE]
Kevin L. Derr, US Architect of the Capitol, DC [E]
James R. Richardson, Lisle Woodridge Fire District, IL [E]
Donald Duplechian, Wilson Fire Equipment, TX [IM]
LawrenceJ. Shudak, UL LLC, lL [RT]
MichaelJ. Ferreira, .JENSEN HUGHES, MD [SE]
Deo Suriya Supanavongs, Honeywelllnternational lnc., lL [M]
Donald Fess, Harvard University, MA [U]
Rep. National Electrical Manufacturers Association
Brian Green, Viking Corporation, Ml (M]
Jeffrey S. Tubbs, Arup, lVIA [SE]
Rep. National Fire Sprinkler Association
Paul G. Turnbull, Siemens Building Technologies, Inc., lL [M]
Geoffrey Harris, Smoke and Fire Engineering Technology Ltd.,
United Kingdom [SE] MichaelJ. Ventola, Space Age Elecu·onics, FL [M]
Rep. ISO TC on Smoke and Heat Conu·ol Systems and Stacy N. Welch, Marriott International, Inc., MD [U]
Components PeterJ. Willse, A.,'V\ XL/Global Asset Protection Services, LLC, CT
John E. Kampmeyer, Sr. , .John E. Kampmeyer, P.E., PA [SE] [l]
David A. Killian, Walt Disney Parks & Resorts, CA [U]

Alternates

Sanjay Aggarwal, JENSEN HUGHES, CA [SE] Wesley Marcks, Xtralis, Inc., Rl [M]
(Ait to Michaei.J. Ferreira) (Ait to Deo Suriya Supanavongs)
Mark Allen Belke, Green heck Fan Corp01·ation, WI [M] John M. McGovern, Engineering Economics, Inc., CO [M]
(Voting Alt. ) (Alt. to Thomas.J. Parrish)
Diane B. Copeland, Dillon Consulting Engineers, Inc., CA [SE] Andrew Neviackas, Arup, MA [SE]
(Voting Alt. ) (Alt. to Jefr
f ey S. Tubbs)
Jason Daniels, Code Consultants, Inc., MO [SE] Fernando Orpano, Siemens lndusu·y, Inc., IL [M]
(Alt. to .Joseph Plati) (Alt. to Paul G. Turnbull)
Donald G. Goosman, Wiss.Janney Elstner Associates, Inc., IL [SE] Luke C. Woods, UL LLC, MA [RT]
(Alt. to Carl F. Baldassarra) (Alt to Lawrence.J. Shudak)
Zachary L. Magnone, .Johnson Controls, Rl [M] Yibing Xin, FM Global, MA [I]
(Alt. to Brian Green) (Alt. to Richard.J. Davis)

Nonvoting

Christian Norgaard Madsen, Norconsult, Norway [SE] John H. Klote, Leesburg, VA [SE]
(Member Emeritus)

Jen Sisco, NFPA Staff Liaison

This list represents the membership at the lime lhe Commillee was balloted on lhe final lexl oflhis edition.
Since that time, changes in the membership may have occunrxl. A key to classifications is found at the
back oflhe document.

NOTE: Membership on a committee shall not in and of itself constitute an endorsement of

the Association or any document developed by the committee on which the member serves.

Committee Scope: This Committee shall have primary responsibility for documents on d1e
design, installation, resting, operation, and maintenance of systems for the control, removal,
or venting of heat or smoke from fires in buildings.

2021 Edition
204-4 SMOKE AND HEAT VENTING

Contents

Chapter I Administration ............................................ 204-5 8.3 Growing (Continuous-Growth) Fires. ............... . 204-11
1.1 Scope. ................................................................... 204-5
1.2 Purpose. (Reserved) ............................................ 204-5 Chapter 9 Sizing Vents ................................................. 204- 12
1.3 Application. .......................................................... 204-5 9.1 General. ............................................................... . 204- 12
1.4 Retroactivity. ........................................................ . 204-5 9.2 Hand Calculations. ................................. 204- 12
1.5 Equivalency. ......................................................... 204-5 9.3 Models. ................................................................. 204-14
1.6 Units and Formulas. ........................................... . 204-5
Chapter I0 Mechanical Smoke Exhaust Systems ......... 204- 15
Chapter 2 Referenced Publications ............................ 204-7 10.1 General. ................................................................ 204- 15
2.1 General. ................................................................ 204-7 10.2 Exhaust Rates. ..................................................... . 204- 15
2.2 NFPA Publications. .............................................. 204-7 10.3 Fire Exposure. ...................................................... 204- 15
2.3 Other Publications. ............................................. 204-7 10.4 Number of Exhaust Inlets. .................................. 204- 15
2.4 References for Extracts in Mandatory Sections. 204-7 10.5 Intake Air. ............................................................. 204- 15

Chapter 3 Definitions .................................................. . 204-7 Chapter II Venting in Sprinklered Buildings ............... 204-15
3.1 General. ................................................................ 204-7 11.1 Design. .................................................................. 204-15
3.2 NFPA Official Definitions. ................................. . 204-7 11.2 Automatic Sprinkler Systems. ............................ . 204-15
3.3 General Definitions. ............................................ 204-7 11.3 Storage Occupancies Protected by Control
Mode Sprinklers. ................................................ 204-15
Chapter 4 Fundamentals ............................................. . 204-8
4.1 Design Ol:>jectives. ............................................... 204-8 Chapter I2 Inspection and Maintenance ...................... 204-16
4.2 Design Basis . ....................................................... . 204-8 12.1 General. ............................................................... . 204-16
4.3 Determination of Contents Hazard. ................... 204-8 12.2 Requirements. ..................................................... . 204-16
4.4 Venting. ................................................................ 204-8 12.3 Inspection, Maintenance, and Acceptance
4.5 Smoke Production. .............................................. 204-8 Testing. ................................................................. 204-16
4.6 Vent Flows. ........................................................... 204-9 12.4 Conduct and Observation of Operational
Tests. ............. . . . ................. . . . ................ . . . . ............. 204-16
Chapter 5 Vents ........................................................... . 204-9 12.5 Air Inlets. ............................................................. . 204-17
5.1 Listed Vents. ......................................................... 204-9 12.6 Ice and Snow Removal. ....................................... 204-17
5.2 Vent Design Constraints. ..................................... 204-9
5.3 Methods of Operation. ........................................ 204-9 Chapter I3 Design Documentation ............................... 204-17
5.4 Dimensions and Spacing of Vents. ..................... 204-9 13.1 Documentation Required. .................................. 204-17
5.5 Mechanical Smoke Exhaust Systems. ................. 204-9 Explanatory Material ..................................
Annex A 204-18
6 Air Inlets ..................................................... 204-10
204-27
Chapter .
Annex B TheTheoretical Basis of lA
VENT ........... .
6.1 Gene•·al. ............................................................... . 204-10
6.2 Construction. ...................................................... . 204-10 Annex C User Guide for ilie lAVENT Computer
6.3 Location. .............................................................. 204-10 Code ........................................................... . 204-40
6.4 Installation. .......................................................... 204-10
6.5 Methods of Operation. ....................................... . 204-10 Annex D Sample Problem Using Engineering
6.6 Dimensions and Spacing of Air Inlets. ............... 204-11 Equations (Hand Calculations) and
6.7 Air Paths. .............................................................. 204-11 IAVENT ...................................................... 204-54
Chapter 7 Draft Curtains ............................................. 204-11 Annex E Predicting ilie Rate of Heat Release of
7.1 General. ................................................................ 204-11 Fires ............................................................. 204-69
7.2 Construction. ...................................................... . 204-11
. 204-11 204-76
�:� �;����� -�-·�-�-��. :.�.. .. ........ .... ....... .... -.-. :·.-.·.·.·.-.-.-......... ....... . ..
. .. .. . . .. Annex F Design Information ....................................
. . . .. . . . .. . 204-11
Annex G Informational References .......................... 204-84
Chapter 8 The Design Fire ........................................... 204-11
204-87
8.1 General. ................................................................
Index
204-11
8.2 Steady (Limited-Growd1) Fires. .......................... 204-11

2021 Edition
 ADMINISTRATION 204-5

NFPA 204 1.2 Purpose. (Reserved)

1.3 Application.
Standard for
1.3.1* This standard shall not apply to ventilation within a
Smoke and Heat Venting building designed for regulation of environmental air for
personnel comfort, to regulation of commercial cooking opet·a­
2021 Edition
tions, to regulation of odor or humidity in toilet and bathing
facilities, to regulation of cooling of production equipment, or
to venting for explosion pressure t-elief.
IMPORTANT NOTE: This NFPA c/Qcument is made available for
use subject to important notices and legal disclnimers. These notices 1.3.2 This standard shall apply to building consu·uction of all
and disclaimers appear in all publications containing this document types.
and may be found under the heading "Important Notices and
Disclaimers Concerning NFPA Standards. " They can also be viewed 1.3.3 This standard shall apply to venting fires in building
at www.nP J a.org!disclaimers or obtained on requestfrom NFPA. spaces with ceiling heights that permit the design fire plume
UPDATES, ALERTS, AND FUTURE EDITIONS: New editions of
and smoke layer to develop.
NFPA codes, standards, recommended practices, and guides (i.e., 1.3.4* This standard shall apply to sintations in which the hot
NFPA Standards) are released on scheduled revision cycles. This smoke layer does not enhance the burning rate of the fuel
edition may be superseded by a later one, or it may be amended array. Vent designs developed with this standard shall not be
outside of its scheduled revision cycle through the issuance of Tenta­ valid for those time intervals where smoke layer temperatures
tive Interim Amendments (TIAs). An o.!Jicial NFPA Standard at any exceed 600°C ( l l l2°F).
point in time consists of the current edition of the document, together
with all TIAs and Errata in effect. To verify that this c/Qcument is the 1.3.5* This standard shall not be valid for fires having heat
current edition or to determine if it has been amended by TIAs or release rates greater than Q;-,.sibiR as determined in accordance
Errata, please consult the National Fire Codes® Subscription Service with the following equation:
or the "List of NFPA Codes & Standards" at www.nfpa.org!docinfo.
In addition to TIAs and Errata, the chJcument infonnation pages also
[1.3.5]
include the option to sign up for alerts for individual c/Qcuments and
to be involved in the development of the next edition. Qpa,;M,. = 12,000(zj
.,1 2
NOTICE: An asterisk (*) following the number or letter
designating a paragraph indicates that explanatory material on where:
the paragraph can be found in Annex A.
A reference in brackets r l following a section or paragraph
Qr,.,; Ne = feasible fire heat release rate (kW)
· z, = height of the smoke layer boundary above the fire base
indicates material that has been extracted from another NFPA (m)
document. Extracted text may be edited for consistency and
style and may include the revision of internal paragraph refer­ 1.3.6* The engineering equations or computer-based models
ences and othet- references as appmpriate. Requests for inter­ incorporated into this standard shall be used to calculate the
pretations or revisions of extracted text should be sent to the time duration that the smoke layer boundary is maintained at
technical committee responsible for the source document. or above the design elevation in a curtained area, relative to
Information on refet·enced and extracted publications can the design interval time.
be found in Chapter 2 and Annex G.
1.4 Retroactivity.

1.4.1 The provisions of this standard shall not be required to

Chapter 1 Administration
be applied reu·oactively.
1 . 1 Scope. 1.4.2 V\There a system is being altered, extended, or renovated,
the requirements of this standard shall apply only to the w01·k
1.1.1* This standard shall apply to the design of venting
being undertaken.
systems for the emergency venting of products of combustion
from fires in buildings. The provisions of Chapters 4 through 1.5 Equivalency. Nothing in this standard is intended to
10 shall apply to the design of venting systems fot· the emer­ prevent the use of systems, methods, or devices of equivalent or
gency venting of product� of combustion from fires in superior quality, strength, fire resistance, effectiveness, durabil­
nonsprinklered, single-story buildings using both hand calcula­ ity, and safety over those prescribed by this standard.
tions and computer-based solution methods as provided in
Chapter 9. Chapter 1 1 shall apply to venting in sprinklered 1.5.1 Technical documentation shall be submitted to the
buildings. authority having jurisdiction to demonstrate equivalency.

1.1.2* This standard shall not specify undet· which conditions 1.5.2 The system, method, or device shall be approved for the
venting is to be provided or required. intended purpose by the authority havingjurisdiction.

1.1.3 Where a conflict exists between a general requirement 1.6 Units and Formulas.
and a specific requirement, the specific requirement shall be 1.6.1 The units of measure in this document are presented in
applicable. the International System (SI) of Units.
1.6.2 The values presented for measurements in this docti­
ment are expressed with a degree of precision appropriate for
p1·actical application and enforcement. It is not intended that

2021 Edition
204-6 SMOKE AND HEAT VENTING

the application or enforcement of these values be more precise total heat release t-are per unit floor area
than the pt-ecision expressed.
1_.6.3 The following symbols define the variables in the equa­ convective heat release rate = x,Q
nons used throughout the body of this standard:
feasible fit-e heat t-elease rate (kW)

A area (of burning surface)

1" = t-adius from fire axis
response time index Tu112
A; inlet area for fresh air, below design level of smoke
RTI
layet- boundary T time constant of heat-responsive element for
convective heating
A, = total vent area of all vents in a curtained area
p density
a = thermal diffusivity, k/pc
ag = fire growth coefficient
Po ambient air density
S center to center spacing of vents
1 = exhaust location factor (dimensionless)
time
Cp specific heat
time to detector activation
vent discharge coefficient
tg = growth time of fire
inlet discharge coefficient
t1g = time to ignition
d = smoke layer depth
t, = design interval time
depth of draft curtain
time to sprinkler activation
D base diameter of the fit-e
t... time to vent opening
g = acceleration of gt-avity
!':!.T = gas temperature rise (from ambient) at detector site
H = ceiling height above base of fire
!':!.T. = adiabatic temperature rise
h, = heat of combustion
!':!.T, = temperantre rise (from ambient) of heat-responsive
hg = heat of gasification
element
K = fraction of adiabatic temperantre rise
T = smoke layer temperature (K)
k = thermal conductivity
1: ambient air temperature
k,/3 = constant used in Equation E.5.1
1:g ignition temperanu-e
kpc = thermal inertia
1: surface temperature
l = thickness
u gas velocity at detector site
L = mean flame height above the base of the fire
W,.;. lateral fire spread by radiation
L1 = flame length, measured from leading edge of
W, largest horizontal dimension of fire
burning region
W,, = width of vent opening in the shorter direction
L, = length of vent opening in the longet- direction
V = flame spread velocity
mass burning rate
Xr = convective fraction of total heat release rate (fraction
mass burning rate per unit area carried as heat in plume above flames) where ;x, is
a convective-heat fraction between 0.6 and 0.7
mass burning rate per unit area for an infinite
;x,. t-adiant ft-acti.on of total heat relea�e rate
diameter pool
y elevation of smoke layer boundary
mass flow rate through vent
J,.u elevation of ceiling
mass flow rate in the plume y,,, elevation of bottom of draft curtain
elevation of the base of the fire above the floor
mass flow rate in the plume at mean flame height (L) Yflre

z_, height of the smoke layer boundary above base of fire

incident heat flux per unit area Z,; height of the smoke layer interface above the base of
the fire
Q = total heat release rate
height ofvit·tual origin above base of fire (below base
(continues)
of fire, if negative)

2021 Edition
 DEFINITIONS 204-7

Chapter 2 Referenced Publications 3.2.3 Labeled. Equipment or materials to which has been
attached a label, symbol, 01· othe1· identifYing mark of an organ­
2.1 * General. The documents or portions thereof listed in ization that is acceptable to the authority having jurisdiction
this chapter are referenced within this standard and shall be and concerned with product evaluation, that maintains peri­
considered part of the requirements of this document. odic inspection of production of labeled equipment or materi­
als, and by whose labeling the manufacturer indicates
2.2 NFPA Publications. National Fire Protection Association, compliance with appropriate standards or performance in a
1 Batterymarch Park, Quincy, MA 02169-7471. specified manner.
NFPA 13, Standard for the Installation of Sprinkler Systems, 2019 3.2.4* Listed. Equipment, materials, or services included in a
edition. list published by an organization that is acceptable to the
NFPA 7'?', National Fi:re Alarm and Signaling Code®, 2019 authority having jurisdiction and concerned with evaluation of
edition. products or services, that maintains periodic inspection of
2.3 Other Publications. production of listed equipment or materials or periodic evalua­
tion of services, and whose listing states that either the equip­
2.3.1 FM Publications. FM Global, 270 Central Avenue, P.O. ment, material, or service meets appropriate designated
Box 7500,Johnston, R1 02919. standards or has been tested and found suitable for a specified
FM 4430, Approval Standanl fa r Heal and Smoke Vents, 2012. purpose.
2.3.2 NIST Publications. National Institute of Standards and
3.2.5 Shall. Indicates a mandat01y requirement.
Technology, 100 Bmeau D1·ive, Stop 1070, Gaithersburg, MD 3.2.6 Should. Indicates a recommendation or that which is
20899-1070. advised but not required.
DETACT-QS (DETector ACTuation - Quasi Steady) soft­ 3.2.7 Standard. An NFPA Standard, the main text of which
\vare. contains only mandatory provisions using the word "shall" to
DETACT-T2 (DETector ACTuation - Time Squared) soft­ indicate requii·ements and that is in a fmm generally suitable
ware. for mandatory reference by another standard or code or for
adoption into law. Nonmandat01y provisions are not to be
LAVENT (Link-Actuated VENTs) software. considered a part of the requirements of a standard and shall
be located in an appendix, annex, footnote, informational
2.3.3 UL Publications. Underwriters Laboratories Inc., 333 note, or other means as permitted in the NFPA Manuals of
Pfingsten Road, Northbrook, IL 60062-2096. Style. When used in a generic sense, such as in the ph1·ase
UL 793, Standardfor Automatically Opemted Roof Umts for Smoke "standards development process" or "standards development
and Heat, 2008, revised 2016. activities," the term "standards" includes all NFPA Standards,
including Codes, Standards, Recommended Practices, and
2.3.4 Other Publications. Guides.
Meniam-Webster's Collegiate Dictionmy, 1 1th edition, Merriam­ 3.3 General Definitions.
Webster, Inc., Springfield, MA, 2003.
3.3.1 Ceiling Jet. A flow of smoke under the ceiling, extend­
2.4 References for Extracts in Mandatory Sections. ing radially from the point of fire plume impingement on the
NFPA 7'?', National Fire Alarm and Signaling Code®, 2019 ceiling.
edition. 3.3.2 Clear (Air) Layer. The zone within a building contain­
NFPA 92, Standani Jar Smoke Control Systems, 2021 edition. ing air that has not been contaminated by the smoke produced
NFPA 318, Standm·dJar the Protection of Semiconductm·Fab·tica­ from a fire in the building, and that is located between the
tion Facilities, 2021 edition. floor and the smoke layer bounda1y
3.3.3* Clear Layer Interface. The boundary between a smoke
Chapter 3 Definitions layer and smoke-free air.
3.1 General. The definitions contained in this chapter shall 3.3.4 Continuously Growing Fires. Fires that, if unchecked,
apply to the terms used in this standard. vVhere terms are not will continue to grow over the design interval time.
defined in this chapter or within another chapter, they shall be 3.3.5 Curtained Area. An area of a building that has its perim­
defined using their ordinarily accepted meanings within the eter delineated by draft curtains, full height partitions, exterior
context in which they are used. Mer riam-Webster:� Collegiate walls, or any combinations thereof.
Dictianm)� 1 1th edition, shall be the somce for the ordinarily
accepted meaning. 3.3.6 Design Depth of the Smoke Layer. The difference
between d1e height of the ceiling and the minimum height of
3.2 NFPA Official Definitions. the smoke layer botmda1y above the finished floor level that
3.2.1 * Approved. Acceptable to the authority having jurisdic­ meets design objectives.
tion. 3.3.7 Design Fire. As used in this standard, the time-rate heat
3.2.2* Authority Having Jurisdiction (AHJ). An organization, release history selected as the input for the calculations pre­
office, or individual responsible for enforcing the requirements scribed herein.
of a code or standard, or for approving equipment, materials,
an installation, or a procedure.

2021 Edition
204-8 SMOKE AND HEAT VENTING

3.3.8 Design Interval Time. The duration of time for which a (2) A draft curtain depth
design objective is to be met, measured from the time of detec­ (3) Type detector and specific characteristics
tor activation. ( 4)Detector spacing
(5) A design interval time, t, following detection for main-
3.3.9* Draft Curtain. A fixed or deployable barrier that taining a clear layer (for continuous-growth fires)
protrudes downward from the ceiling to channel, contain, or (6) Total vent area per curtained area
prevent the migration of smoke. (7) Distribution of individual vents
3.3.10* Effective Ignition. The time at which a t-squared (8) An air inlet area
design fire starts. 4.3 Determination of Contents Hazard.
3.3.1 1 Fuel Array.A collection and arrangement of materials 4.3.1 The determination of contents hazard shall take into
that can support combustion. account the fuel loading and the rate of heat release anticipa­
3.3.12 Heat Detector. A fit·e detector that detects either ted from the combustible materials or flammable liquids
abnormally high temperature or rate-of-temperature rise, or contained within the building.
both. f72, 20191 4.3.2 The heat t·elease rate of the design fire shall be quanti­
3.3.13 Limited-Growth Fires. Fires that are not expected to fied in accordance with Chapter 8.
grow beyond a predictable maximum heat release rate. 4.4 Venting.
3.3.14 Mechanical Smoke Exhaust System. A dedicated or 4.4.1 Design Objectives. In order to satisfy design objectives,
shared-duty fan system designed and suitable for the removal of a vent system shall be designed to slow, stop, or reverse the
heat and smoke. descent of a smoke layer produced by fire in a building, by
3.3.15 Plastics. exhausting smoke to the exterior.
3.3.16 Plugholing. The condition whet·e air fi·om below the 4.4.2* Vent System Designs and Smoke Production.
smoke layer is pulled through the smoke layer into the smoke 4.4.2.1 Vent systems shall be designed in accordance with this
exhaust due to a high exhaust rate. [92, 2021] standard by calculating the vent area required to achieve a
3.3.17 Smoke. The airborne solid and liquid particulates and mass rate of flow through d1e vents that equals the mass rate of
gases evolved when a material undergoes pyrolysis or combus­ smoke production.
tion, together with the quantity of air that is entrained or other­ 4.4.2.2 Vent system designs shall limit the descent of the
wise mixed into the mass. f318, 2021] smoke layer to the design elevation of the smoke layer boun­
3.3.18* Smoke Layer. The accumulated d1ickness of smoke dary.
below a physical or thermal barrier. (92, 2021] 4.4.2.3 Alternative vent system designs shall be permitted to
3.3.19* Smoke Layer An ef:lective boundat-y
Boundary. be developed in accordance with this standard by calculating
centered in a transition zone between the dense portion of the the vent area required to achieve a mass rate of flow through
smoke layer and the first indication of smoke. the vents that is less than the mass rate of smoke production,
such that the descent of the smoke layer is slowed to meet the
3.3.20 Vent. A� used in this standard, a device or consU"l.tction design objectives.
that, when activated, is an opening directly to the exterior at or
near the roof level of a building that relies on the buoyant 4.4.3* Vent Mass Flow. Vent system designs shall be computed
fot·ces created by a fire to exhaust smoke and heat. on the basis that the mass flow rate through a vent is deter­
mined primarily by buoyancy pressure.
3.3.21 Vent System. A system used for the removal of smoke
and heat from a fire that utilizes manually or automatically 4.5 Smoke Production.
operated heat and smoke vents at roof level and that exhausts 4.5.1 * Base of the Fire. For the purposes of the equations in
smoke from a reservoir bounded by exterior walls, interior this standard, the base of the fire shall be at the bottom of the
walls, or draft curtains to achieve the design rate of smoke mass burning zone.
flow through the vents, and that includes a provision for
makeup air. 4.5.2* Fire Size. Burning and entrainment rates of possible
fire scenarios shall be considered before establishing the condi­
tions of the design fire.
Chapter 4 Fundamentals
4.5.3* Entrainment.
4.1 * Design Objectives. The design objectives to be achieved
over the design interval time by a vent system design during a 4.5.3.1 The entrainment formulas specified in this standard
design fire or design fires shall include the following: shall be applied only to a single fire origin.
(1) The minimum allowable smoke layer boundary height 4.5.3.2* Virtual Origin. Predicted plume mass flow above the
(2) The maximum allowable smoke layer temperature top of the flame shall take into account the virtual origin, z., of
the fire as determined in 9.2.3.2.
4.2* Design Basis. A design for a given building and it�
combustible contents and their distribution shall comprise
selecting a design basis (limited-growth versus continuous­
gmwth fire) and establishing the following parametet·s:
( 1 ) Layout of curtained areas

2021 Edition
 VENTS 204-9

4.6 Vent Flows. 5.3.5* All vents shall be designed to open by manual means.
Means of opening shall be either internal or extet·nal, as
4.6.1 * Buoyancy and Vent Flow.
approved by the authority having jurisdiction.
4.6.1.1 Flow through a vent shall be calculated on the basis of
5.3.6 Vent� designed for remote operation shall utilize
buoyancy pressure difference, assuming that no pressure is approved fusible links and shall also be capable of actuation by
contributed by the expansion of gases. an elecu·ic power source, heat-responsive device, or other
4.6.1.2* Beneficial wind effects shall not be taken into approved means.
account when calculating vent areas. 5.3.7 Vent� designed to activate by smoke detection or other
4.6.1.3 Ait· inlets and vents shall be located to avoid adverse activation methods external to the vent shall be approved in
wind effects. accordance with Section 5.1.

4.6.2* Inlet Air. 5.4 Dimensions and Spacing of Vents.

4.6.2.1 Predicted vent flows shall take into account the area of 5.4.1 The dimensions and spacing of vents shall meet the
inlet air openings. requirements of 5.4.1.1 and 5.4.1.2 to avoid plugholing.

4.6.2.2 Inlet air shall be introduced below the smoke layer 5.4. 1.1 The area of a unit vent shall not exceed 2tf-, where dis
boundary. the design depth of the smoke layer.

4.6.2.3 Wall and ceiling leakage above the smoke layer boun­ 5.4.1.2* For vents with L.,/W" > 2, the \vidth, W", shall not
dary in the curtained area shall not be included in vent flow exceed the design depth of the smoke layer, d.
calculations. (See Chapter 6fodnformatiM M aiT inlets.)
5.4.2* In plan view, the center-to-center spacing of vents in a
rectangular mau·ix, S, as shown in Figure 5.4.2(a), within a
Chapter 5 Vents curtained area shall not exceed 4H, where H is the ceiling
height as shown in Figure 5.4.2(b), parts (a) through (d).
5.1 * Listed Vents. Normally closed vents shall be listed and
5.4.3* The spacing of vents, in plan view, shall be such that
labeled in accordance with UL 793, StandmrJ. for Automatically
the horizontal distance from any point on a wall or draft
Operated Roof lknts for Smoke and Heat, FM 4430, Appmval Stand­
curtain to the center of the nearest vent, within a curtained
ard for Heat and Smoke Vents; or other approved, nationally
area, does not exceed 2.8H as indicated in Figure 5.4.3.
recognized standards.
5.4.4 The total vent area per curtained area shall be sized to
5.2 Vent Design Constraints.
meet the design ol�ectives and the performance objectives rela­
5.2.1 * The means of vent actuation shall be selected with tive to the design fire, determined in accordance with Chap­
regard to the full range of expected ambient conditions. ter 8.
5.2.2* Vents shall consist of a single unit (vent), in which the 5.5 Mechanical Smoke Exhaust Systems. Mechanical smoke
entire unit (vent) opens fully with the activation of a single exhaust systems shall be designed in accordance with Chap­
detector, or multiple unit� (vents) in rows or arrays (ganged ter 10.
vents) in which the units (vents) open simultaneously with the
activation of a single heat detector, a fusible link, a smoke

r
detector, or other means of detection to satisfY the venting
requirements for a specific hazard.
5.2.3* V\There the hazard is localized, vents shall open directly �-----S->4H -----�

El- EJ
above such hazard.
- - - ----- - - - ----- - - - ----- -

5.2.4 Vents, and their supporting su·ucture and means of

actuation, shall be designed so that they can be inspected visu­
ally after installation.
5.3 Methods of Operation.

5.3.1 * Normally, closed vents shall be designed to open auto­

5[
matically in a fire to meet design objectives or to comply with
perfot·mance objectives or requit·ements.
5.3.2* Vents, other than thermoplastic drop-out vents, shall be
designed to fail in the open position such that failure of a vent­
operating component results in an open vent. GJ-- --- ----- --- ----- --- ----- - GJ
5.3.3 Vents shall be opened using gravity or other approved
PLAN VIEW
opening force.
5.3.4 The opening mechanism shall not be prevented from FIGURE 5.4.2(a) Vent Spacing in Rectangular Matrix (plan
opening the vent by snow, roof debris, or internal projections. view).

2021 Edition
204-10 SMOKE AND HEAT VENTLNG

///////)///?� (a) Flat roof

1
/

(b) Gabled roof PLAN VIEW

FIGURE 5.4.3 Vent Location near a Wall or Draft Curtain

(plan view).

6.3.2 In larget· buildings whet·e there is more than one

curtained area, air inlets shall be permitted to be provided by
vents in other nonadjacent curtained areas.
/
(c) Sloped roof 6.4 Installation.

6.4.1 Materials of construction and methods of installation for

air inlets shall resist expected extremes of temperature, wind,
building movement, rain, hail, snow, ice, sunlight, corrosive
environment, internal and external dust, dirt, and debris.
6.4.2 The means of air inlet actuation shall be selected with
H regard to the full t·ange of expected ambient conditions.

7/,T/,T/,T/,T/,T/,T/1/,T/,T/,T/,T/,T/,T/,T/,T/,7,0'/
6.4.3 To satisfY the vent system requirements, air inlets shall
consist of one of the following:
(1) A single unit (air inlet) in which the entire unit (air inlet)
(d) Sawtooth roof opens fully with the activation of a single detector
(2) Multiple units (air inlets) in mws or an·ays (ganged air
FIGURE 5.4.2(b) Measurement of Ceiling Height (H) and inlets) in which the units (air inlets) open simultaneously
Curtain Board Depth (d,). with the activation of a single heat detector, a fusible link,
a smoke detector, or other means of detection to satisfY
the vent system requirements
Chapter 6 Air Inlets 6.4.4 Air inlets and their supporting su·uctures and means of
actuation shall be designed such that they can be inspected
6.1 * General. Air inlets shall be provided for supplying visually after installation.
makeup air for vent systems.
6.5 Methods of Operation.
6.2 Construction. Air inlets consisting of louvers, doors,
dampers, windO\vs, shutters, or other approved openings shall 6.5.1 Air inlets shall be either constantly open or automati­
be designed and constructed to provide passage of outdoor air cally placed in the open position after a fire is detected.
into the building. 6.5.2 Air inlets shall be designed to open in a fire to meet
6.3* Location. Air inlet� shall be installed as indicated in 6.3.1 design objectives or to comply with performance objectives or
or 6.3.2. requirements.

6.3.1 Air inlets shall be installed in external walls of the build­ 6.5.3 Air inlets shall be designed to fail in the open position
ing below the height of the design level of the smoke layer such that failure of an air inlet-operating component results in
boundat-y and shall be clearly identified ot· marked as ait· inlets. an open air inlet.
6.5.4 Air inlets shall be opened using an approved means as
the opening force.

2021 Edition
 THE DESIGN FIRE 204-11

6.5.5 Air inlet opening mechanisms shall not be prevented Chapter 8 The Design Frre
fi·om opening the air inlet by snow, debt·is, or internal projec­
tions. 8.1�' General.

6.5.6 Operating mechanisms for air inlets shall be jam-proof, 8.1.1 The design fire shall be selected fi·om among a number
conosion-t·esistant, dust-resistant, and resistant to pressure of challenging candidate fires, consistent with the building and
differences arising from applicable positive or negative loading its intended use, considering all of the following factors that
resulting from environmental conditions, process operations, tend to increase the challenge:
overhead doors, or traffic vibrations. (1) A low-level flame base (usually floor level)
6.5.7 Air inlets designed for remote operation shall be activa­ (2) Increasing fire growth rate
ted by approved devices and shall be capable of actuation by an (3) Increasing ultimate heat release t·ate in the design inter­
eleco·ical powet· source, heat-responsive device, or other val time
approved means. 8.1.2 The candidate fire that produces a vent system design
6.6 Dimensions and Spacing of Air Inlets. meeting the design objectives for all candidate fires shall be
selected as the design fire.
6.6.1 The total inlet area per curtained area shall be sized to
meet the design objectives and the performance objectives or 8.2 Steady (Limited-Growth) Fires.
requirements specified relative to the design fire, determined 8.2.1 For steady fires, ot· fires that do not develop beyond a
in accordance with Chapter 8. maximum size, the required vent area per curtained area shall
6.6.2 One inlet area shall be permitted to serve more than be calculated based on the maximum calculated heat release
one curtained area. rate ( Q and Q,.), the associated distance from the fire base to
the design elevation of the smoke layer boundary (z,), and the
6.6.3* The ait· velocity at the plume shall not exceed 1 m/sec predicted fire diameter (D).
(3.28 ft/sec).
8.2.2* Steady fires shall be permitted to include special-hazard
6.7 Air Paths. Air paths from an air inlet opening to the fires and fires in occupancies with conceno·ations of combusti­
curtained area where smoke is being exhausted shall be at least bles separated by aisles of sufficient width to prevent the spread
three times the size of the air inlet opening. of fire by radiation beyond the initial fuel package or initial
storage array.
Chapter 7 Draft Curtains 8.2.3 The minimum aisle \vidth t·equired to pt·event lateral fire
spread by radiation, W,.1,, shall be calculated for radiant heat
7.1 * General. Where the spacing between walls exceeds the
flux from a fire based on an ignition flux of 20 kW/m 2 (2.5
limits in Section 7.4, draft curtains shall be provided.
hp/ft2) in accordance with the following equation:
7.2* Construction.

7.2.1 Draft curtains shall remain in place and shall confine [8.2.3]
smoke when exposed to the maximum predicted temperature �.;,. = 0.042Q�;
for the design interval time, assuming a design fire in close
proximity to the draft curtain.
where:
7.3 Location and Depth. W,.1, = minimum aisle \vidth required to pt·event lateral fire
spread by radiation (m)
7.3.1 * Draft curtains shall extend vertically downward from Q,. .., = max imum anticipated heat release rate (kW)
the ceiling the minimum distance required so that the value of
d" as shown in Figure 5.4.2(a), is a minimum of 2 0 percent of 8.2.4 The fire diameter, D, shall be the diameter of a circle
the ceil.ing height, H, measured as follows: having the same at·ea as the floor area of the fuel concentra­
tion.
(1) For flat roofs and sawtooth roofs with flat ceiling areas,
from the ceiling to the floor 8.2.5 The heat release rate shall be the heat release rate per
(2) For sloped roofs, from the center of the vent to the floor unit area times the floor area of the fuel concenu·ation, using
the maximum storage height above the fire base and associated
7.3.2 Where there are differing vent heights, H, each vent
heat release rate.
shall be calculated individually.
8.2.6* The heat release rate per unit area shall be determined
7.4 Spacing.
by test or from published data acceptable to the AHJ.
7.4.1 * Neither the length nor the width of a curtained area
8.3 Growing (Continuous-Growth) Fires.
shall exceed eight times the ceiling height.
8.3.1 * For fuel configurations that have been tested, the fire
7.4.2* \\The re draft curtains extend to a depth of less than
growth shall be modeled to follow the test results acceptable to
30 percent of the ceiling height, the distance between draft
the AHJ. For other fuel configurations that have not been
curtains shall be not less than one ceiling height.
tested, a t-squared fire growth as shown in Figure 8.3.1 shall be
used with a fire gro\vth coefficient based on published data
acceptable to the AHJ and in accordance with the following
equation:

2021 Edition
204-12 SMOKE AND HEAT VENTLNG

8.3.5 The heat release rate at the end of the design interval
[8.3.1] time shall be calculated in accordance with the following equa­
tion:

[8.3.5]

where:
Q = heat release rate of fire (kW)
t = time from effective ignition following an incubation
period (sec)
tg = time at which the fire exceeds an intermediate size of where:
1055 kW (sec) Q = heat relea�e rate (kW)
t, = time at end of design interval (sec)
8.3.2* A t-squared fire growth shall be permitted to be td = time of detection (sec)
expressed in terms of a fire grovvth coefficient, all' in lieu of tg = time at which fire exceeds 1055 kW (sec)
growth time, tg, as follows:
8.3.6 The end of the design interval time, t,, shall be selected
to correspond to the design objectives as determined for d1e
[8.3.2] specific project design.
8.3.7 The instantaneous diameter of the fire needed for the
calculation of L and z. shall be calculated from the instantane­
where: ous heat release rate, Q, and data on the heat release rate per
Q = heat ,-elease rate of fire (kW) unit floor area, Q11, where Q" is proportional to storage height
ag = fire growth coefficient (kW/sec2) in accOI-dance with the following equation:
t = time (sec)
8.3.3 The instantaneous heat release rate per unit height of
the storage array shall be considered to be constant, regardless
of the storage height. Accordingly, for different storage
D=
( )1/2
4Q
[8.3.7]

heights, the growth time, tg, shall be calculated as being inver­ nQ"
sely proportional to the square root of the storage height, and
the fire growth coefficient, all' shall be calculated as being where:
directly proportional to the storage height. (See Section Fl.) D = instantaneous fire diameter (m)
8.3.4* The vent system shall maintain the smoke boundary
Q = instantaneous heat release rate (kW)
layer above the design elevation from the time of effective igni­ Q;' = heat release rate per unit floor area (kW /m2)
tion until the end of the design interval time, t, where t, is
measured fi-om the time of detection, td. Chapter 9 Sizing Vents

9.1 * General.

9.1.1 * The design vent area in a curtained area shall equal d1e
vent area required to meet the design objectives for the most
challenging fire predicted for the combustibles within the
Continuously growing fire � curtained area.
9.1.2 Vent areas shall be determined using hand calculations
3000
in accordance with Section 9.2 or by use of a computer-based
model in accordance with Section 9.3.
9.1.3 The design fire used in the evaluation of a proposed
�
"'
2000 vent design in accordance with Section 9.1 shall be determined
Ql in accordance with Chapter 8.
�
� 9.1.4* Vent systems shall be designed specifically for the
I hazard of each curtained area in a building.
1000
9.2 Hand Calculations.

9.2.1 Vent System Designs. Vent systems, othet- than those

complying with Section 9.3, shall be sized and actuated to meet
Time (l) design objectives in accordance with Section 9.2.
9.2.2 Design Concepts.

FIGURE 8.3.1 Conceptual illustration of Continuous­ 9.2.2.1 * Equilibrium shall be assumed as illustrated in Figure
Growth Fire. 9.2.2.1, where symbols are as defined in Section 1.6.

2021 Edition
 SIZING VENTS 204-13

9.2.3.6 When the mean flame height, L, is below the smoke

layer boundary (L <z,), the mass flow rate in the fire plume
shall be calculated in accordance with the following equation:

[9.2.3.6]

where:
rh1, = mass flow rate in d1e plume (kg/s)
(2r = convective heat release rate = 0.7Q (kW)
z, = height of the smoke layer boundary above d1e base of
FIGURE 9.2.2.1 Schematic of Venting System. d1e fire (m)
z. = height of virtual origin above the base of the fire (if
9.2.2.2 The smoke layer boundary shall be at or above the below the base of the fire, z. is negative) (m)
bottom of the draft curtains. 9.2.3.7 When the mean flame height (L) is equal to or above
9.2.2.3 At equilibrium, the mass flow rate into the smoke layer the smoke layer boundary (L?. z,), the mass flow rate shall be
calculated in accordance with the following equation:
shall be equal to the mass flow rate out of d1e vent or vents ('lhp
= mv ).
[9.2.3.7]
9.2.3 Mass Flow Rate in Plume.

9.2.3.1 * The mean flame height shall be calculated in accord­

ance with the following equation:
where:
ml' = mass flow rate in the plume (kg/sec)
[9.2.3.1]
(2r = convective heat release rate = 0.7Q (kW)
L = -1.02D + 0.235Q 21 5
z, = height above the base of the fire (m)
L = mean flame height (m)
where:
L = mean flame height above the base of the fire (m) 9.2.3.8 The base of the fire shall be the lowest point of the
D = base diametet· of fire (m) fuel array.
Q = total heat release rate (kW)
9.2.4* Mass How Rate Through Vents.
9.2.3.2 The virtual origin, z., is the effective point source of
9.2.4.1 * The mass flow through the vent shall be calculated in
the fit·e plume and shall be calculated in accordance with the
accordance with the following equation:
following equation:

[9.2.4.1]
[9.2.3.2]
z. = 0.083Q21 5 - 1.02D

where:
z. = virtual fire origin
Q = total heat t·elease rate (kW)
D = base diameter of fire (m) where:
rh, = mass flow through vent (kg/sec)
9.2.3.3 Smoke entrainment relationships shall be applicable
to axisymmetric plumes. cd,v = vent discharge coefficient
A, = vent area (m2)
9.2.3.4 For line-like fires where a long, narrow plume is
P. = ambient density (kg/m3)
created by a fuel or storage array, the smoke production calcu­
g = acceleration due to gravity (9.81 m/sec2)
lated in accordance with this standard shall be applicable only
d = smoke layer depth (m)
if the height of the smoke layer boundary above the base of the
fire (z,) is greater than or equal to four times the largest hori­ 1: = ambient temperamre (K)
T = smoke layer temperature (K)
zon tal dimension of the fire, W,.
cd,i = inlet discharge coefficient
9.2.3.5 If z, is smaller than 4 W,, the smoke production rates A; = inlet area (m2)
calculated in accordance with this standard shall be increased
9.2.4.2* The dischat·ge coefficients fot· the vents and inlets
by the factor [HV,/ (z,) F13.
used shall be dwse provided by d1e vent or inlet manufacturer.
If no data are available, the discharge coefficient shall be taken
from Table 9.2.4.2 unless an analysis or data acceptable to the

2021 Edition
204-14 SMOKE AND HEAT VENTLNG

Table 9.2.4.2 Default Discharge Coefficients for Vents and (3) By heat or smoke detectors installed on a regular matrix
Inlets within the curtained area in accordance with NFPA. 72
(4) By other approved means shown to meet design objec­
Discharge tives
Coefficient 9.2.5.4.2 For calculating both the detection time, td, of the
Vent or Inlet Type [(d, v) and (d, i)] first detector to operate and the detection time, t,., of ti1e
Louvered with blades at 90 degrees to 0.55 detector controlling the actuation of the last vent to operate in
airflow a curtained area prior to the end of the design interval time,
Flap type or door open at least 55 degrees the location of the design fire shall be assumed to be the
Drop-out vent leaving clear opening farthest distance possible from both the first and last detectors
to operate the vents within the curtained area.
Flap type m- door open at least 30 degrees 0.35
Fixed weather louver with blades at 45 0.25 9.2.5.4.2.1* Detection times for heat detectors or fi.1sible links
degrees shall be determined in acco•-dance with NFPA. 72.
9.2.5.4.3 Detection times for smoke detectors shall be deter­
AFij are provided by the designer to validate the use of an alter­ mined as the time to reach a certain temperature rise, � 7� at
native value. activation. In the case of conti.nuous-gwwth, t-squared fires, gas
temperatures shall be determined in accordance with the
9.2.4.3 The smoke layer temperature, 7� used in 9.2.4.1 shall following equation, where � T is assumed to be 0 when the
be determined from the following equation: numerator of the first bracket is zero or negative:

[9.2.4.3] [9.2.5.4.3]

where:
T = smoke layer temperature (K) where:
1: = ambient temperature (K) T = temperature (C)
K = fraction of convected energy contained in the smoke lg = fire growth time (sec)
layer gases (see 9.2.4.4) H = ceiling height above the base of the fire (m)
r = radius from fire axis (m)
Q,. = convective heat release rate (kW)
Cp = specific heat of the smoke layer gases (kj/kg-K) 9.2.5.4.3.1 * The temperature •·ise for activation shall be based
=
rh1, plume mass flow rate (kg/sec) (see 9.2.3) on dedicated tests, or the equivalent, for the combustibles asso­
ciated with the occupancy and the detector model to be in­
9.2.4.4 The value of K used in Equation 9.2.4.3 shall be 0.5, stalled.
unless an analysis acceptable to the AHJ is provided by the 9.2.5.4.3.2 Where ti1e data described in 9.2.5.4.3.1 are not
designer to validate the use of an alternative value. available, a minimum temperature rise of 20°C (68°F) shall be
9.2.5 Required Vent Area and Inlet Area. used.

9.2.5.1 Vent Area. The required vent area shall be the mml­ 9.2.5.4.4 Detection Computer Programs.
mum total area of all vents within a curtained area required to 9.2.5.4.4.1 * As an alternate to ti1e calculations specified in
be open to prevent the smoke from descending below the 9.2.5.4.2, DETACT-T2 shall be permitted to be used to calculate
design level of the smoke layer boundary when used in detection times in continuous-growth and t-squared fires.
coi�Wlction with the required inlet area.
9.2.5.4.4.2* As an alternative to the calculations specified in
9.2.5.2 Inlet Area. The required inlet area shall be the mini­ 9.2.5.4.2, DETACT-QS shall be permitted to be used to calcu­
mum total area of all inlets required to be open to prevent the late detection times in fires of any fire growth history.
smoke from descending below the design level of the smoke
layer botmdary when used in co1�unction with the required 9.2.5.4.4.3 Other computer programs determined to calculate
vent area(s). detection times reliably shall be pennitted to be used when
approved by the AHJ.
9.2.5.3 Area Calculation. The required vent area and inlet
areas shall be calculated by equating the plume mass flow rate 9.3 Models.
determined in 9.2.3 and the vent mass flow rates determined in
9.3.1 Vents, other than vent systems designed in accordance
9.2.4.
\'lith Section 9.2, shall be sized and actuated to meet design
9.2.5.4 Detection and Activation. objectives in accordance \'lith Section 9.3.

9.2.5.4.1 * Detection, for the purpose of automatically actuat­ 9.3.2 The computer model LAVENT or other approved math­
ing vents, shall be by one of the following methods: ematical models shall be used to assess the effects of the design
fire and to establish that a proposed vent system design meet�
(1) By either heat or smoke at the vent location
design objectives. (See Section F:2.)
(2) By activation of fire protection systems

2021 Edition
 VENTING IN SPRINKLERED BUILDINGS 204-15

9.3.3 When models other than LAVENT are used, evidence 10.4.5* For exhaust inlets centered less d1an twice the diame­
shall be submitted to demonsu-ate efficacy of the model to eval­ ter from the neat-est wall, a value of 0.5 shall be used for l·
uate the time-varying events of a fire and to calculate the effect
10.4.6* For exhaust inlets on a wall, a value of 0.5 shall be
of vent designs reliably in terms of the design objectives.
used for 1.
9.3.4 The design fit-e used in the evaluation of a pt-oposed
10.4.7* The ratio d/D; shall be gt-eater than 2, where D; is the
vent system design in accordance with Section 9.3 shall be
determined in accordance with Chapter 8. diametet- of the inlet.
10.4.8 For rectangular exhaust inlets, D; shall be calculated
Chapter I 0 Mechanical Smoke Exhaust Systems using Equation 10.4.8 as follows:

10.1* General. [1 0.4.8]

10.1.1* Mechanical smoke exhaust systems shall be permitted = 2ab
D
in lieu of the vent systems described in Chapter 9. ' a+b
10.1.2 Mechanical smoke exhaust systems and vent systems
where:
shall not serve the same curtained area.
D; = diameter o f exhaust inlet
10.1.3 Mechanical smoke exhaust systems shall be designed in a = length of the inlet
accordance with Sections 10.2 du·ough 10.4. b = width of the inlet

10.2 Exhaust Rates. Exhaust rates per curtained area shall be 10.4.9 V\There multiple exhaust inlets are required to prevent
not less than the mass plume flow rates, m P• as determined in plugholing (see 10.4.1), the minimum separation distance shall
accordance with 9.2.3, unless it can be demonstrated that a be calculated using Equation 10.4.9 as follows:
lower exhaust rate will prevent the smoke from descending
below the design level of the smoke layer boundary during the [1 0.4.9]
design period.
S..,;,. = 0.9V,1 12
10.3 Fire Exposure.

10.3.1 Mechanical smoke exhaust systems shall be capable of where:

functioning under the expected fire exposure. smin = minimum edge-to-edge separation between inlets (m)
V: = volumetric flow rate of one exhaust inlet (m3/sec)
10.3.2 The temperature of the smoke layer shall be deter­
mined in accordance with 9.2.4.3 and 9.2.4.4. 10.5 Intake Air. Intake air shall be provided to make up air
requit-ed to be exhausted by the mechanical smoke exhaust
10.4* Number of Exhaust Inlets. systems. (See Chapter 6 fO"r additional information on the location of
10.4.1 The minimum number of exhaust inlets shall be deter­
air inlets.)
mined so that d1e maximum flow rates for exhaust without
plugholing are not exceeded. Chapter 1 1 Venting in Sprinklered Buildings
10.4.2 More than the minimum number of exhaust inlets
required shall be permitted. 11.1 * Design. Where provided, the design of venting for
sprinklered buildings shall be based on an engineering analysis
10.4.3* The maximum volumeu-ic flow rate that can be acceptable to the Alfj", demonstrating that the established
exhausted by a single exhaust inlet without plugholing shall be objectives are met. (See Section F.3.)
calcttlated using Equation 10.4.3.
1 1 .2* Automatic Sprinkler Systems. The automatic sprinkler

(-
system shall be designed in accordance with NFPA 13.
[ 10.4.3]
l/ 2 11.3* Storage Occupancies Protected by Control Mode Sprin­

J
klers.
vmnx = 4.16yd" 12 T. T,
J;, 11.3.1 Where draft cmtains are provided, they shall be located
over the longitudinal center of an aisle.
where:
1 1 .3.2 The aisle width shall not be less than 1.5 times the spac­
V.nax = maximum volumetric flow rate without plugholing at 7�
(m3/sec) ing between sprinklers in d1e direction perpendicular to the
draft curtain.
1 = exhaust location factor (dimensionless)
d = depth of smoke layer below the lowest point of the 1 1 .3.3 Sprinklers shall be located on both sides of the curtain
exhaust inlet (m) per NFPA 13 requirements for sprinkler placement with
7� = absolute temperature of the smoke layer (K) respect to walls.
1: = absolute ambient temperantre (K)
1 1.3.4 The aisle width required by 11.3.2 shall not be required
10.4.4* For exhaust inlets centered no closer than twice the if a full height partition is used in lieu of a draft curtain.
diameter from the nearest wall, a value of 1 shall be used for l·

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204-16 SMOKE AND HEAT VENTLNG

Chapter 1 2 Inspection and Maintenance flashing condition shall be noted at the time of inspection, and
any deficiency shall be cot-rected.
12.1* General. Smoke and heat venting systems and mechani­
12.3.3.4 Any soiling, debris, or encumbrances that could
cal smoke exhaust systems shall be inspected and maintained in
accordance with Chapter 12. impair the operation of the vent shall be promptly removed
without causing damage to the vent.
12.2* Requirements.
12.3.4 Inlet Air Sources. Where required for the operation of
12.2.1 Mechanically Opened Vents. Mechanically opened vent systems, intake air sources shall be inspected at the same
vents shall be provided with manual release devices that allow ft-equency as vents.
direct activation to facilitate inspection, maintenance, and
12.4 Conduct and Observation of Operational Tests.
replacement of actuation components.
12.4.1 Mechanically Opened Vents and Air Inlets.
12.2.2 Thermoplastic Drop-Out Vents. Thermoplastic dmp­
out vents do not allow nondesu·uctive operation; however, 12.4.1.1 Mechanically opened vents and air inlets shall be
inspection of installed units shall be conducted to ensure that operated during tests by simulating actual fire conditions.
the units are installed in accordance with the manufacturer's
instructions and that all components are in place, undamaged, 12.4.1.2 The restraining cable at the heat-responsive device
and free of soiling, debris, and extraneous items that might (or other releasing device) shall be disc01mected, releasing the
interfere with the operation and function of the unit. resu·aint and allowing the u·igger or latching mechanism to
operate.
12.2.3 Inspection and Maintenance. The inspection and
maintenance of multiple-function vent� shall ensure that other 12.4.1.3* When the heat-responsive device resu·aining cable
functions do not impair the intended fire protection operation. for mechanically opened vent� or air inlets is under tension,
observation shall be made of its whip and u·avel path to deter­
12.3 Inspection, Maintenance, and Acceptance Testing. mine any possibility that the vent, building construction
12.3.1 Inspection Schedules.
featt1re, or service piping could obsu·uct complete release. Any
interference shall be corrected by removal of the obstruction,
12.3.1.1 A written inspection schedule and procedm·es for enclosure of cable in a suitable conduit, or other appropt·iate
inspection and maintenance shall be developed. arrangement.
12.3.1.2 Inspection programs shall provide written notations 12.4.1.4 Following any modification, the unit shall be retested
of the elate and time of inspections and of discrepancies found. fix evaluation of adequacy of cot-rective measures.
12.3.1.3 All deficiencies shall be corrected immediately. 12.4.1.5 Latches shall release smoothly and the vent or air
inlet shall open immediately and move through its design
12.3.1.4* Vents shall be inspected and maintained in an oper­
travel to the fully opened position without any assistance and
ating condition in accordance with Chapter 12. without any problems such as undue delay indicative of a stick­
12.3.2 Mechanically Opened Vents. ing weatl1er seal, corroded or unaligned bearings, or distortion
binding.
12.3.2.1 An acceptance performance test and inspection of all
mechanically opened vents shall be conducted immediately 12.4.1.6 Manual releases shall be tested to veri£)' that the vents
following installation to establish that all operating mecha­ and air inlets operate as designed.
nisms function pmperly and that installation is in accordance 12.4.1.7 All operating levers, latches, hinges, and weather­
with this standard and the manufacturet·'s specifications. sealed surfaces shall be examined to determine conditions,
12.3.2.2* Mechanically opened vents shall be inspected and such as deterioration and accumulation of foreign material. An
subjected to an operational test annually, following the manu­ operational test shall be conducted aftet· cotTections are
facturer's recommendations. completed, when conditions are found to warrant corrective
action.
12.3.2.3* All pertinent characteristics of performance shall be
recorded. 12.4.1.8 Following painting of the interior ot· exterior of vents
and air inlets or the addition of sealants or caulking, the units
12.3.2.4 Special mechanisms, such as gas cylinders, thermal shall be opened and inspected to check for paint, sealant�, or
sensors, or detectors, shall be checked annually or as specified caulking that causes the parting sm·faces to adhere to each
by the manufacnu·er. other.
12.3.3 Thermoplastic Drop-Out Vents. 12.4.1.9 Heat-responsive devices coated with paint or other
12.3.3.1* An acceptance inspection of all thermoplastic drop­
substances that could affect their response shall be replaced
out vents shall be conducted immediately after installation and with devices having an equivalent temperature and load rating.
shall include vet·ification of compliance with the manufacnu·­ 12.4.2 Thermoplastic Drop-Out Vents.
er's drawings and recommendations by visual examination.
12.4.2.1 All weather-sealed surfaces on thetm· oplastic drop-<>ut
12.3.3.2* Thermoplastic drop-<>ut vent� shall be inspected vents shall be examined to determine any adverse conditions,
armually in accordance with 12.4.2 and the manufactttrer's such as any indication of deterioration and accumulation of
recommendations. foreign material. Any adverse condition that interferes with
12.3.3.3 Changes in appearance, damage to any components,
normal vent operation, such as caulking or sealant bonding tl1e
fastening security, weather tightness, and the adjacent roof and drop-out vent to the frame, shall be corrected.

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 DESIGN DOCUlVIENTATION 204-17

12.4.2.2 Following painting of the interior or exterior of the 12.4.3.4 Exhaust System Maintenance.
frame ot- flashing of the vents, the units shall be inspected for
12.4.3.4.1 During the life of the building, maintenance shall
paint adhering surfaces together; any paint that interferes with
normal operation shall be removed or the vent shall be be performed to ensure that mechanical smoke-exhaust
replaced with a new, listed and labeled unit having comparable systems will perform their intended function under fire condi­
operating characteristics. tions.
12.4.3.4.2 Maintenance of the systems shall include the testing
12.4.2.3 Manual relea�es shall be tested annually.
of all equipment, including initiating devices, fans, dampers,
12.4.3 Inspection, Maintenance, and Testing of Mechanical and controls.
Smoke-Exhaust Systems.
12.4.3.4.3 Equipment shall be maintained in accordance with
12.4.3.1 Component Testing. the manufacturer's recommendations.
12.4.3. 1 . 1 The operational testing of each individual system 12.4.3.5 Inspection Schedule.
component of the mechanical smoke-exhaust system shall be
12.4.3.5.1 A written inspection schedule and procedures for
performed as each component is completed during construc­
tion. inspection and maintenance for mechanical smoke-exhaust
systems shall be developed.
12.4.3.1.2 It shall be documented in writing that each individ­
12.4.3.5.2 Inspection programs shall provide written notations
ual system component's installation is complete and that the
component has been tested and found to be functional. of date and time of inspections and for discrepancies found.
12.4.3.5.3 All system components shall be inspected semiann­
12.4.3.2 Acceptance Testing.
ually in conjunction with operational tests.
12.4.3.2.1 Acceptance tests shall be conducted to demonstrate
12.4.3.5.4 Any deficiencies noted in the system components or
that the mechanical smoke-exhaust system installation complies
with and meets the design objectives and is functioning as smoke-exhaust system performance shall be con-ected immedi­
designed. ately.
12.5 Air Inlets.
12.4.3.2.2 Documentation from component system testing
shall be available for review during final acceptance testing. 12.5.1 Air inlets necessary for operation of smoke and heat
12.4.3.2.3 If standby power has been provided for the opera­
vents or mechanical smoke-exhaust systems shall be maintained
tion of the mechanical smoke-exhaust system, the acceptance clear and free of obstructions.
testing shall be conducted while on both normal and standby 12.5.2 Operating air inlet louvers, doors, dampers, and shut­
power. ters shall be examined and operated to assure movement to
12.4.3.2.4 Acceptance testing shall be performed on the
fully open positions.
mechanical smoke-exhaust system by completing the following 12.5.3 Operating equipment shall be maintained and Jubdca­
steps: ted as necessary.
(1) Activate the mechanical smoke-exhaust system. 12.6 Ice and Snow Removal. Ice and snow shall be removed
(2) VerifY and record the operation of all fans, dampers, from vents promptly, following any accumulation.
doot-s, and related equipment.
(3) Measure fan exhaust capacities, air velocities through
inlet doors and grilles, or at supply grilles if there is a Chapter 13 Design Documentation
mechanical makeup air system.
13.1 * Documentation Requrred. All of the following docu­
12.4.3.2.5 Operational tests shall be performed on the appli­
ment� shall be generated by the designer during the design
cable part of the smoke-exhaust system wherever there are process:
system changes and modifications.
(1) Design brief
12.4.3.2.6 Upon completion of acceptance testing, a copy of (2) Conceptual design repon
all operational testing documentation shall be provided to the (3) Detailed design report
owner and shall be maintained and made available fot- review (4) Operations and maintenance manual
by the AHJ.
13.1.1 Design Brief. The design brief shall contain a state­
12.4.3.3 Periodic Testing. ment of d1e goals and objectives of d1e vent system and shall
12.4.3.3.1 Mechanical smoke-exhaust systems shall be tested
provide the design assumptions to be used in the concepntal
semiannually by persons who are knowledgeable in the opera­ design.
tion, testing, and maintenance of the systems. 13.1.1.1 The design brief shall include, as a minimum, all of
12.4.3.3.2 The results of the tests shall be documented and
the following:
made available for inspection. (1) System performance goals and design objectives (see
Section 4.1 and 4.4.1)
12.4.3.3.3 Tests shall be conducted under standby power
(2) Per fonnance criteria (including design tenability criteria,
where applicable. where applicable)
(3) Building characteristics (height, area, layout, use, ambi­
ent conditions, other fire protection systems)

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204-18 SMOKE AND HEAT VENTLNG

(4) Design basis fire(s) (see 4.5.2 and Chapter 8) 13.1.4.5 The building owner shall be responsible for all system
(5) Design fire location(s) testing and shall maintain records of all periodic testing and
(6) Identified design constraints maintenance using the operations and maintenance manual.
(7) Proposed design approach
13.1.4.6 The building owner shall be responsible for provid­
13.1.1.2 The design brief shall be developed in d1e first stage ing a copy of me operations and maintenance manual, includ­
of me design process to assure d1at all stakeholders understand ing testing results, to all tenants of me space protected by me
and agree to the goals, objectives, design fire, and design vent system.
approach, so that me conceptual design can be developed on
13.1.4.7 The building owner and tenants shall be responsible
an agreed-upon basis. Stakeholders shall include, as a mini­
mum, the building owner and the AHJ. for limiting the use of d1e space in a manner consistent with
me limitations provided in me operations and maintenance
13.1.2 Conceptual Design Report. The conceptual design manual.
report shall provide me details of the conceptual design, based
upon the design brief, and shall document the design calcula­
Annex A Explanatory Material
tions.
Annex A is not a pat·t ofthHequirements of this NFPA document trut is
13.1.2.1 The conceptual design shall include, as a minimum,
includedfm· informational pwposes only. This annex contains explan­
all of the following design elements and me technical basis for atory material, nwnbenJd to COTrespond with the applicable text pam­
the design elements: graphs.
(1) Areas of curtained spaces
A.l.l.l This standard incorporates engineering equations
(2) Design depm of me smoke layer and draft curtain depth
(3) Detection memod, detector characteristics, and spacing (hand calculations) and references models to pmvide a
(4) Design interval time (if applicable) designer with me tools to develop vent system designs. The
(5) Vent size and number per curtained area, memod of vent designs are based on selected design objectives, stated in 4.4.1,
operation, and vent spacing related to specific building and occupancy conditions. Engi­
(6) Inlet vent area(s), location(s), and operation method neering equations are included for calculating vent flows,
smoke layer depms, and smoke layer temperantres, based on a
13.1.2.2 The conceptual design report shall include all design prescribed burning rate. Examples ming the hand calculations
calculations performed to establish me design elements, all and me LAVENT (Link-Actuated VENTs) computer model are
design assumptions, and all building use limitations mat arise presented in Annex D.
out of the system design.
Previous editions of this document have included tables list­
13.1.3 Detailed Design Report. ing vent areas based on preselected design objectives. These
tables were ba�ed on the hot upper layer at 20 percent of me
13.1.3.1 The detailed design report shall provide documenta­
ceiling height. Different layer depths were accommodated by
tion of the vent system as it is to be installed. using a multiplication factor. Draft curtain and vent spacing
13.1.3.2 The detailed design report shall include, as a mini­ rules were set. Minimum clear visibility times were related to
mum, all of the following: fire growm rate, ceiling height, compartment size, curtain
depm, and detector activation times, using engineering equa­
( 1) Yen t and draft curtain specifications tions.
(2) Inlet and vent operation system specifications
(3) Detection system specifications The following list provides a general description of the
( 4) Detailed inlet, vent, and draft curtain siting information significant phenomena mat occur during a fire when a fire­
(5) Detection and vent operation logic venting strategy is implemented:
(6) Systems commissioning pmcedures (1) Due to buoyancy, hot gases rise vertically from me
13.1.4 Operations and Maintenance Manual. The operations combustion zone and flow horizontally below the roof
and maintenance manual shall provide to the building owner until blocked by a vertical barrier (a wall or draft curtain),
the t-equirements to ensure the intended operation of the vent dms forming a layer of hot gases below the roof.
system over the Iife of the building. (2) The volume and temperantre of gases to be vented are a
function of the fire's rate of heat release and the amount
13.1.4.1 The procedures used in me initial commissioning of of air entrained into the buoyant plume produced.
me vent system shall be described in the manual, as well as the (3) As the depth of the layer of hot gases increases, the layer
measured performance of the system at the time of commis­ temperatm-e continues to rise and me vents open.
sioning. ( 4) The operation of vents within a curtained area enables
13.1.4.2 The manual shall describe me testing and inspection
some of me upper layer of hot gases to escape and thus
requirement� for the system and system components and the slows me thickening t-are of me layer of hot gases. Wim
required frequency of testing. (See Chapte·r 12 for testing sufficient venting area, the mickening rate of the layer
frequency.) can be arrested and even reversed. The rate of discharge
through a vent of a given area is p1·imarily determined by
13.1.4.3 The manual shall describe me assumptions used in d1e depth of me layer of hot gases and me layer tempera­
the design and shall provide limitations on me building and its rure. Adequate quantities of replacement inlet air from
use mat arise out of the design assumptions and limitations. air inlets located below me hot upper layer are needed if
the products of combustion-laden upper gases are to be
13.1.4.4 Copies of me operations and maintenance manual
exhausted according to design. See Figure A. l . l . l (a) for
shall be provided to me owner and to the AHJ. an illustration of me behavior of fire under a vented and

2021 Edition
 ANNEX A 204-19

curtained roof, and Figure A. l . l . l (b) for an example of a A.l.3.6 Large, undivided floor areas present extremely diffi­
roof with vents. cult fu·efighting problems because the fire department might
need to enter these areas in order to combat fires in cenu-al
The majority of the information provided in this standard portions of the building. If the fire department is unable to
applies to nonsprinklered buildings. A limited amount of guid­ enter because of the accumulation of heat and smoke, fire fight­
ance is provided in Chapter 11 for sprinklered buildings. ing efforts might be reduced to an application of hose su-eams
The provisions of this standard can be applied to the top to perimeter areas while fire continues in the interior. Window­
story of multiple-story buildings. Many features of these provi­ less buildings also present similar firefighting problems. One
sions would be difficult or impt·acticable to incorporate into fire protection tool that can be a valuable asset for firefighting
the lower stories of such buildings. operations in such buildings is smoke and heat venting.

A.l.l.2 The decision whether to provide venting in a building An appropriate design time facilitates such activities as locat­
depends on design objectives set by a building owner or occu­ ing the fire, appraising the fire severity and its extent, evacuat­
pant or on local building code and fire code requirements. ing the building, and making an informed decision on the
deployment of personnel and equipment to be used for
A.l.3.1 See NFPA 90A for ventilation to regulate environmen­ fi refightin g.
tal air fix personnel comfort. See NFPA 96 for regulation of
commercial cooking operations. See NFPA 68 for venting for A.2.1 Some of these documents might also be referenced in
explosion pressure relief. this standard for specific informational pm·poses and are there­
fore also listed in Annex G.
A.l.3.4 The distance from the fu·e base to the smoke layer
boundary, z, is a dominant variable and should be considered A.3.2.1 Approved. The National Fire Protection Association
carefully. Additionally, some design situations can result in does not approve, inspect, ot- certify any installations, proce­
smoke layer temperantres, as expressed in Equation 9.2.4.3, dures, equipment, or materials; nor does it approve or evaluate
that exceed 6000C ( l l l 2°F). In such cases, the radiation from testing laboratories. In determining the acceptability of installa­
the smoke layer can be sufficient to ignite all of the combusti­ tions, procedm·es, equipment, or materials, the authority
bles under the curtained area at this temperature, and perhaps having jurisdiction may base acceptance on compliance with
in the adjacent area, which is unacceptable. NFPA or other appropriate standards. In the absence of such
standards, said authority may require evidence of proper instal­
A.l.3.5 The feasibility of roof venting should be questioned lation, procedure, or use. The authority having jurisdiction
when the heat release rate approaches values associated with may also refer to the listings or labeling practices of an organi­
ventilation control of d1e burning process (i.e., where the fit·e zation that is concerned with pt·oduct evaluations and is thus in
becomes controlled by the inlet air replacing the vented hot a position to determine compliance with appropriate standards
gas and smoke). Ventilation-controlled fires might be unable to for the current production of l isted items.
support a clear layer.
A.3.2.2 Authority Having Jurisdiction (AHJ). The phrase
To maintain a clear layet� venting at heat release rates "authority having jurisdiction," or its acronym AHJ, is used in
greater than Q;_.,;1,., necessitates vent areas larger than those NFPA documents in a broad manner, since jurisdictions and
indicated by the calculation scheme provided in d1is standard. approval agencies vary, as do their responsibilities. Where
public safety is primary, the authority having jurisdiction may
be a federal, state, local, or other regional department or indi­
Draft curtains vidual such as a fu·e chief; fire marshal; chief of a fire preven­
tion bureau, labor department, or health department; building
official; elecu-ical inspector; or others having statutory author­
ity. For insurance purposes, an insurance inspection depart­
ment, rating bureau, or od1er insm·ance company
origin representative may be the authority having jurisdiction. In
curtains many circumstances, the property owner or his or het- designa­
FIGURE A. I. I. I (a) Behavior of Combustion Products
ted agent assumes the role of the authority having jurisdiction;
Under Vented and Curtained Roof.
at government installations, the commanding officer or depart­
mental official may be the authority having jm·isdiction.
A.3.2.4 Listed. The means for identifying listed equipment
may vary for each organization concerned with product evalua­
tion; some organizations do not recognize equipment as listed
unless it is also labeled. The authority having jurisdiction
should utilize the system employed by the listing organization
to identify a listed product.
A.3.3.3 Clear Layer Interface. See Figure A.3.3.3 for a
description of the smoke layer interface, smoke layer, and first
indication of smoke.
A.3.3.9 Draft Curtain. A draft curtain can be a solid fixed
obstruction such as a beam, girder, soffit, or similar material.
Altemately, a deployable barrier can be used that descends to a
fixed depth during its operation.
FIGURE A. I . I . I (b) View of Roof Vents on Building.

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204-20 SMOKE AND HEAT VENTLNG

distance between the base of the fire and the point at which the
smoke plume enters the smoke layer.
A.4.5.2 Because smoke production is related to the size of a
fire, it follows that, all factors being equal, larger fires produce
Smoke more smoke. Entrainment, however, is strongly affected by the
layer distance between the base of a fire and the bottom of the hot
Smoke layer
Transition
zone
� interface layer. The base of the fire (where combustion and entrainment
begin) should be selected on the basis of the worst ca5e. It is
-
First indication possible for a smaller fire having a base near the floor to
of smoke produce more smoke than a larger fire with a base at a higher
elevation. Air entrainment is assumed to be limited to the cleat­
height between the base of the fire and the bottom of the hot
layer. The buoyant plume associated with a fire produces a flow
into the hot upper layer. As the plume impinges on the ceiling,
tl1e plume turns and forms a ceiling jet. The ceiling jet flows
FIGURE A.3.3.3 First Indication of Smoke. radially outward along the ceiling.
A.4.5.3 vVhere the possibility of multiple fires and, therefore,
A.3.3.10 Effective Ignition. See Figure 8.3.1 for a conceptual multiple plumes exists, smoke production rates increase
illustration of continuous f'it-e growth and effective ignition beyond the rate predicted for a single plume for a fire of equiv­
time. alent output. Multiple fires are beyond the scope of this stand­
ard.
A.3.3.18 Smoke Layer. See Figure A.3.3.3 for a description of
the clear layer interface, smoke layer, and smoke layer boun­ A.4.5.3.2 Plume mass flow above the flame level is based on
dary. the concept that, except for absolute scales, the shapes of veloc­
ity and temperature profiles at the mean flame height are
A.3.3.19 Smoke Layer Boundary. See Figure A3.3.3 for a invariable. This concept leads to an expression for mass flow
description of the clear layer interface, smoke layer, and smoke above the flames that involves the scrcalled viTtual origin, a
layer boundary. point source from which the plume above the flames appears
A.4.1 Design objectives for a vent system can include one or to originate. The virtual origin might be above or below the
more of the following goals: base of the fire.

(1) To provide occupants with a safe path of travel to a safe A.4.6.1 It is assumed that openings exist to the outside and
area therefore no pressure results from the expansion of ga�es. Also,
(2) To facilitate manual firefighting wind effects are not taken into account because wind might
(3) To reduce the damage to buildings and contents due to assist or interfere witl1 vent flows, depending on specific
smoke and hot gases circumstances. It is also assumed that the fire environment in a
building space is divided into twu zones - a hot upper layer
A.4.2 Tests and studies provide a basis for the division of occu­ and a relatively cool, clear (comparatively free of smoke) lower
pancies into classes, depending on the fuel available for contri­ region. vVhen a fire grows to a size approaching ventilation­
bution to fire. Wide variation is found in the quantities of limited burning, the building might no longer maintain a cleat­
combustible materials in the many kinds of buildings and areas lower region, and this standard would no longer be applicable.
of buildings. Finally, caution must be exercised when using this standard for
A.4.4.2 The heat release rate of a fire, the fire diameter, and conditions tmder which the upper-gas-layer temperature
the height of the clear layer above the base of the fire are approaches 600°C ( l l l 2 °F), because flashover might occur
major factors affecting the production of smoke. within the area. When a fire develops to flashover or
ventilation-limited burning, the relationships provided in this
A.4.4.3 Mass flow through a vent is governed mainly by the standard are not applicable.
vent area and the depth of the smoke layer and its tempera­
ture. Venting becomes more effective with smoke temperature Buoyancy pressure is related to the depth of the hot layer,
diffet-entials between ambient temperature and an upper layer the absolute temperature of the hot layer, the temperature rise
of approximately l l0°C (230°F) or higher. vVhere temperature above ambient of the hot layer, and the density of the ambient
differences of less than l l 0°C (230°F) are expected, vent flows air. The mass rate of flow of hot gases through a vent is a func­
might be reduced signi ficantly; therefore, consideration should tion of vent area, layer depth, and hot layer temperature. The
be given to using powered exhaust. NFPA 92 should be consul­ temperature of the hot layer above ambient affects mass flow
ted for guidance for power venting at these lower tempera­ through a vent. Maximum flow occurs at temperature differen­
tures. ces of approximately 3000C (572°F) above ambient. Flows at
other temperature differentials are diminished, as shown in
The vent designs in this standard allow the fire to reach a Figure A.4.6.1.
size such that the flame plume enters the smoke layer. Flame
height may be estimated using Equation 9.2.3.1. A.4.6.1.2 In order to provide a design that is not dependent
on beneficial wind effects, design calculations are carried out
A.4.5.1 The rate of smoke production depends on the rate of that ignore wind effects and that are based only on buoyancy
air entrainment into a column of hot gases produced by and effects (and fan assistance for mechanical systems).
located above a fire. Entrainment is affected by the fire diame­
ter and rate of heat release, and it is strongly affected by the

2021 Edition
 ANNEX A 204-21

1.0 A.5.3.1 An automatic mechanism for opening the roof vents is

�----
/
stipulated for effective t·elease of heat, smoke, and gaseous by­

r---
products. The means of automatic vent actuation must take the
E 0.8
anticipated fire into consideration, and an appropriate means
::>

II
of opening vents should be used. If design objectives cannot be
E
·x met using heat-actuated devices, smoke detectors with appro­
� priate linkages to open vent� or other devices that respond
0 0.6
more quickly should be considet·ed for use.
c::
0
:u A.5.3.2 Latching mechanisms should be jam-proof, corrosion­
<II
.1:: 04 resistant, dust-resistant, and resistant to pressure differences
� .
;;:::
at·ising fmm applicable positive or negative loading t·esulting
from environmental conditions, process operations, overhead
gJ
<II doors, or traffic vibrations.
::2 0.2
A.5.3.5 The location of tl1e manual device must be coordina­
ted witl1 tactics of the reporting fire department.
0
200 400 600 800 1000 If not actually mounted on the vent, the manual device can
Temperature above ambient K be connected to the vent by mechanical, electrical, or any
other suitable means, protected a� necessary to remain opera­
FIGURE A.4.6.1 Effect of Temperature on Mass Flow ble for the design period.
Through a Vent.
A.5.4.1.2 See Figure 5.4.2(b) for tl1e measurement of ceiling
height and curtain board depth.
Nevertheless, it is important to consider wind effects since
adverse wind effects can reduce or even reverse vent flow. A.5.4.2 The spacing of vents is limited to 4H to assure that
Exhaust vents and air inlets should be located so that under ceiling jet temperatures at the vent are sufficiently high to
any wind conditions there is an ovet·all wind suction effect from operate the thermal actuating mechanism at the vent. The
inlet to exhaust. spacing limit specified is designed to achieve ceiling jet temper­
ature above ambient at the nearest vent, not less than half the
This is normally achieved when the roof slope is 30 degrees plume temperature above ambient at the point of plume
or less and vents have a horizontal clear space at least three impact on the ceiling. (See Figure A5.4.2, which reflects the
times the height difference from any taller structures such as maximwn allowable spacing of 4H.)
parapets, roof lights, or taller roofs.
A.5.4.3 The limitation on horizontal distance from a potential
Otherwise, if the designet· cannot show by calculation or by fire axis adjacent to a draft curtain or wall is intended to assure
data that there will be no adverse wind effects, a mechanical ceiling jet temperatures at the vent are sufficiently high to acti­
smoke extract system should be used. vate the thermal actuating mechanism. The spacing limit speci­
fied is designed to achieve ceiling jet temperantre above
A.4.6.2 To function as intended, a building venting system
ambient at the nearest vent, not less than half the plume
needs sufficiently large fresh air inlet openings at low levels. It
temperature above ambient at tl1e point of plume impact on
is essential that a dependable means for admitting or supplying
the ceiling. (See Figun: A.5.4.3.) This requirement does not
inlet air be provided promptly after the first vent opens.
reflect the potential for reduced enu·ainment for a fire adja­
A.5.1 There is an ISO standard for vents (ISO 21927-2, Smoke cent to a wall. This conservatism was knowingly accepted.
and Heat Contml Systems - PaTt 2: Specification fm· natuml smoke
and heat exhaust ventilators) . The ISO standard is technically
equivalent to European (EN) standards for these products.
Products that carry the CE mark, which is mandatory for sale of
these products within the European Union, are subject to inde­
pendent testing and ongoing factory production conu·ol by
Notified Bodies appointed by national governments. The stand­
ard is BS EN 12101-2, Smoke and Heat Contml Systems - Pm·t 2:

l
Specification for natuml smoke and heat exha·ust ventilator.;. 2.8H r = 2.8H
Nearest vent
TviT0
/).
A.5.2.1 Compatibility betw·een the vent-mounting elements
(e.g., holding power, electrochemical interaction, wind lift,
/ ' -�Fire axis
4H
building movement) and the building st ructure to which they , ,,

' 6 T(r=o/ To
'

are attached needs to be ensured. ,

'
', ' ,
,,
,

.. ......'
l I
,"' ',
1 , , I
A.5.2.2 To avoid inadvertent operation, it is important that the
: , ' :

�---------------------------�
actuating means be selected with regard to the full range of I
,'
, t

expected ambient conditions.

A.5.2.3 Dip tanks or discrete solvent storage areas are exam­
ples of localized hazards where the vents are to be located PLAN VIEW

directly above such hazard.

FIGURE A.5.4.2 Vent Spacing in Rectangular Matrix, When r
= 2.8 H, (� T.ITo) = 0.5 {�T( r = 0)/T.) (plan view) .

2021 Edition
204-22 SMOKE AND HEAT VENTLNG

A.6.1 The simplest method of int roducing makeup air into Excess depressurization of the space will increase door open­
the space is through direct openings to the outside, such as ing forces for outward-opening doors and risk slanuning closed
doors and louvers, which can be opened upon system activa­ for inward-opening doors. Neither situation is acceptable.
tion. Such openings can be coordinated with the architectural
design and can be located as required below the design smoke Research indicates that people can move reasonably freely
layer. For locations having mechanical smoke exhaust systems against an airflow of up to 10 m/sec (32.8 ft/sec).
where such openings are impractical, a powered supply system A.7.1 Draft curtains are provided for prompt activation of
could be considered. This could possibly be an adaptation of vents and to increase vent effectiveness by containing the
the building's HVAC system if capacities, outlet grille locations, smoke in the cmtained area and increasing the depth of the
and velocities are suitable. For such systems, means should be smoke layer. A draft curtain is intended to be relatively smoke­
provided to prevent supply systems from opet·ating until tight. The function of a draft curtain is to intercept ilie ceiling
exhaust flow has been established, to avoid pressurization of jet and the entrained smoke produced by a fire in the building.
the fire area. For those locations where climates are such that The curtain should prevent the smoke from spreading along
the damage to the space or contents could be extensive dm·ing the underside of the roof deck to areas of the building located
testing or frequent inadvertent operation of the system, consid­ beyond the draft curtain and should create a hot smoke layer
eration should be given to heating the makeup air. See that develops buoyancy forces sufficient to exhaust the smoke
NFPA 92 fot· additional information on mechanical systems. through the vent openings in the roof. A fi.lll-height partition
A.6.3 Normal practice has been to provide air inlet from low­
or wall, including an exterior wall, can serve as a draft curtain.
level air inlets as recommended in previous editions of this A.7.2 Materials suitable for use as draft curtains can include
standard. In some buildings this may be difficult to achieve, steel sheeting, cementitious panels, and gypsum board or any
due either to lack of suitable clear wall area or to concerns materials that meet the performance criteria in Section 7.2.
about loss of security when the air inlets open. In buildings There is an ISO standard for draft curtains (ISO 21927-1, Smoke
containing more than one curtained area, it can be possible to and Heat Contwl Systems - Part 1: Specification for smoke barriers) .
open vents in curtained areas not affected by smoke to provide The ISO standard is technically equivalent to the European
inlet air instead. If this is done, then the vents must meet all (EN) standard for these product�. Products that carry the CE
the requirements of Chapter 6. mark, which is mandatory for sale of these product� within the
A.6.6.3 The inlet air velocity should be limited for tl1ree
European Union, are subject to independent testing and ongo­
reasons: ( 1) to avoid disturbing the fire plume and causing ing factory production control by Notified Bodies appointed by
excess air eno·ainment, (2) to limit the degree of depressuriza­ national governments. The standard is BS EN 12101-1, Smoke
tion of the space and consequent effects on door opening and and Heat Cont-rol Systems - PaTt 1: Specification jm· smoke barriers.
closing, and (3) to avoid incoming air hampering escape of A.7.3.1 If d, exceeds 2 0 percent of H, H-d, should be not less
occupants. than 3 m (9.8 ft). For Figure 5.4.2(b), parts (a) through (d),
NFPA 92 sets a limit of 1.02 m/sec (200 ft/min) to minimize tl1is concept is valid where f".. d/ d, is much less than 1.
disturbance of the plume, which will create more entrainment Consideration should be given to minimizing of the expec­
ilian anticipated. ted smoke layer depth with respect to the occupancy. Such
arrangement can allow the smoke layer to be maintained above
the top of equipment or storage, thus maximizing visibility and
reducing nonthennal damage to content5. For buildings of
limited height, it can also allow the designer to utilize the
primary so·ucntral frame to act as a draft curtain (if solid­
webbed) ot· support one (if open-webbed), thus ,-educing costs.
Nearest vent Also, in a transient situation, prior to achieving equilibrium
D.TviTo mass flow, if ilie smoke layer extends below the top of equip­
ment or storage, that volume displaced by equipment or stor­
age should be subo·acted from available space for the smoke
layer to accumulate, or the smoke layer depth will extend
below that estimated.
A.7.4.1 To ensme that vents remote from the fire within the
curtained comparonent are effective, the distance between
draft cUt·tains or between walls must be limited.
A.7.4.2 From reanalysis of tl1is issue based on Delichatsios
Draft f l 981l, Heskestad and Delichat�ios [1978], and Koslowski and
Motevalli f1994].
A.8.1 Chapter 8 presents techniques for predicting the heat
release rate of various fi.tel arrays likely to be present in build­
ings where smoke and heat venting is a potential fire safety
PLAN VIEW
provision. It primarily addresses the estimation of fuel concen­
FIGURE A.5.4.3 Vent Spacing near a Draft Curtain, When r trations found in storage and manufacturing locations.
= 2.8H, (aTviT.) =0.5 (aT(r= 0/T.) (plan view). NFPA 92 addresses the types of fuel arrays more common to
the types of building situations covered by that document. The

2021 Edition
 ANNEX A 204-23

methods provided in Chapter 8 for predicting the rate of heat Table A.8.2.6 Unit Heat Release Rates for Commodities
t-elease are based on "fi-ee burning" conditions, in which no
ceiling or smoke layer effects are involved. Heat Release Rate
A.8.2.2 The minimum aisle width to prevent lateral spread by (kWper m2 of
1·adiation, W..1" in Equation 8.2.3, is based on Alpert and Ward Commodity floor area)*
[1984]. The values produced by Equation 8.2.3 can be Wood pallets, stacked 0.46 m high 1,420
produced from the following equation if x. is assumed to be (6%-12% moisture)
0.5: 'Wood pallets, stacked 1 .52 m high 4,000
(6%-12% moisture)
Wood pallets, stacked 3.05 m high 6,800
[A.8.2.2]
(6%-12% moisture)
.1 x, . Wood pallets, stacked 4.88 m high 10,200
q; = --

4m·- (6%-12% moisture)

MaiJ bags, filled, stored 1.52 m high 400
A.8.2.6 The heat release rate is taken as the heat release t-ate Cartons, compartmented, stacked 1,700
per unit area times the floor area of the fuel concentration. 4.5 m high
The maximum foreseeable storage height (above the fire base) PE letter trays, filled, stacked 8,500
and associated heat release rate should be considered. 1.5 m high on cart
PE trash barrels in cartons, stacked 2,000
The heat release rate per unit area might be available from 4.5 m high
listings for a given storage height, such as Table A.8.2.6. To FRP shower stalls in cartons, sacked
t 1 ,400
establish estimates for other than specified heights, it can be 4.6 m high
assumed that the heat release rate per unit area is proportional PE bottles packed in compartmented 6,200
to the storage height, based on tests (Yu and Stavrianidis, 1991) cartons, stacked 4.5 m high
and the data in Table A.8.2.6 fot- wood pallets. Fot- fuel configu­ PE bottles in cartons, stacked 4.5 m high 2,000
rations that have not been tested, other procedures should be PU insulation board, rigid foam, stacked 1,900
used. See Annex E for estimating heat release rates of other 4.6 m high
fuel arrays. PSjars packed in comparunented cartons, 14,200
stacked 4.5 m high
There is a distinct possibility that a combustible storage array
PS tubs nested in cartons, stacked 5,400
could collapse before the end of the design interval of the vent­
4.2 m high
ing system. The design interval might end, for example, when
PS toy parts in cartons, stacked 4.5 m high 2,000
manual firefighting is expected to begin. The fire diameter
PS insulation board, rigid foam, stacked 3,300
increases, cont ributing to increased smoke production (via a
4.2 m high
lowet- flame height and virmal origin). However, the heat
PVC bottles packed in compartmented 3,400
release rate and fire growth rate after collapse are likely to be
cartons, stacked 4.5 m high
smaller than with no collapse. Consequently, it is reasonable to
PP tubs packed in compartmented 4,400
assume that the net effect of collapse is not significant for the
cartons, stacked 4.5 m high
calculation procedure.
PP and PE film in rolls, stacked 6,200
A.8.3.1 The growth time, tg, is a measure of the fire growth 4.1 m high
rate - the smaller the growth time, the faster the fire grows. Methyl alcohol 740
Gasoline 2,500
A.8.3.2 By comparing Equations 8.3.1 and 8.3.2, the following Kerosene 1,700
relation exists: Fuel oil, no. 2 1,700
PE: polyethylene. PP: polypropylene. PS: polystyrene. PU:
[A.8.3.2] polyurethane. PVC: polyvinyl chloride. FRP: fiberglass-reinforced
polyester.
1000
a. = - .- *Heat release rate per unit floor area of fully involved combustibles,
• rg based on negligible radiative feedback from the surroundings and
100 percent combustion efficiency.
A.8.3.4 Design objectives and the design interval time, t,
should take into consideration all of the following critical
events:
tive means is known or can be calculated using the procedures
(l) Arrival and deployment of the emergency response team contained herein or can be established as acceptable by a
(2) Arrival and deployment of firefighters from the public specific listing, specific test data, or engineering analysis. Acti­
fire department vation by heat detectors, smoke detectors, thermoplastic drop­
(3) Completion of evacuation out vent panels, or other approved means is acceptable as long
( 4) Othet- critical events a� the design objectives are met.
A.9.1 The procedures in Chapter 9 are based on the auto­ The equations and procedures for hand calculations in
matic activation of vent� by a heat-responsive device with an Section 9.2 and the models in Section 9.3 address the venting
established response time index (RTI) and known activation of limited-growth fires and continuously growing fires.
temperamre. These assumptions do not preclude other means
of vent activation, as long as the activation time of the alterna-

2021 Edition
204-24 SMOKE AND HEAT VENTLNG

A.9. 1 . 1 The vent area in a curtained area should not be factor is 0.38, and at a temperamre rise of 2 0 K, it is 0.24, or
t·equired to exceed the vent area calculated for the largest about one-half its maximum value. Consequently, roof venting
limited-growth fire predicted for the combustibles beneath any by natural ventilation becomes increasingly less effective as tl1e
curtained area. Using sufficiently small concentrations of smoke layer temperan1re decreases. For low smoke layer
combustibles and aisles of sufficient width to prevent spread temperatures, powered ventilation as covered in NFPA 92
according to Equation 8.2.3, it might be possible to satisfy vent­ should be considered.
ing requirement� by using vent areas smaller than those
required for a vent design and a continuous-growth fire. \<\There high upper-layer temperatures of 400 K above ambi­
ent are anticipated, 80 percent of the predicted vent flow is
A.9.1.4 Many large facilities have buildings or areas subject to expected to be achieved with an inlet area/vent area ratio of 1,
differing fire hazards. whereas it is expected that 90 percent of the vent flow will
z, is the height of the smoke layer
result from a ratio of 2. V\'here relatively low upper-layer
A.9.2.2.1 In Figure 9.2.2.1,
temperatures, such as 2 0 0 K above an1bient, are expected, a
boundary above the base of the fire; H is the distance between ratio of inlet air/vent area of 1 would result in about
the base of the fire and the ceiling; d, is the depth of the draft 70 percent of the pt·edicted vent flow, whereas a ratio of 2
curtains; dis the depth of the smoke layer; m j, is the mass flow would be expected to produce about 90 percent of the predic­
rate of hot gas from the fire plume into the smoke layer; m � is ted vent flow.
the mass flow rate of hot gas out of the vent (or vents) in the
curtained area; and Av is the vent area in the curtained area A.9.2.4.2 The aerodynamic vent area is always smaller than tl1e
(total vent area in the curtained area if more than one vent is geometric vent area, A,. A discharge coefficient of 0.6 should
provided). be reasonable for most vents and for doors and windows tl1at
open at least 45 degrees. However, the discharge coefficient
The vent area calculated for equilibrium conditions corre­ can be different for other types of openings. For example, an
sponds to the area needed for a long-term steady fire or to the opening with a louver can have a coefficient ranging between
area needed at the end of a design interval for a slow-gt·owing 0.1 and 0.4.
fire. For shorter-term steady fires and for faster-growing fires,
the calculated equilibrium vent area will prevent the smoke A.9.2.5.4.1 For continuous-growth fit·es, the earlier the fire is
layer boundary fi·om descending completely to the bottom of detected and vents acmated, tl1e smaller the fire size at tl1e end
the draft curtains. Therefore, equilibrium calculations repre­ of the design interval and the smaller the required vent area.
sent a safety factor in the design. In the case of limited-growth fires, the earlier the fire is detec­
ted and the vent� actuated, tl1e less likely to occur are an initial
A.9.2.3.1 The mass flow t·ate in the plume depends on underspill of smoke at the draft curtains and smoke layer
whether locations above or below the mean flame height are descent to low heights.
considered (i.e., whether the flames are below the smoke layer
boundary or reach into the smoke layer). If a design objective is to confine smoke to the curtained
area of origin, tl1e time the last required vent opens, t"", should
A.9.2.4 The calculations in this section assume that the vent is not exceed the time the smoke layer boundary drops below
exhausting only smoke from the smoke layer. When the smoke draft curtains, which can be determined in accordance with
layer is at its design depth, the provisions for avoidance of Equation A.9.2.5.4.1a for steady fires and Equation A.9.2.5.4.1b
plugholing in Section 5.4 will ensure that this is so. fix unsteady fires.
However, during part of the time period when the smoke
layer is descending to its design height, the vents will extract a
- ' [ (tQ('r' /H'") )] [A.9.2.5.4.la]

H A,/ H'
mixture of smoke from the smoke layer and the ambient air
2- .
from below the smoke layer. They will therefore extract less - 0.67 0.28 In
smoke than the calculations indicate, causing tl1e smoke layer
to descend at a faster rate.
Existing research has provided formulae to assess at what
[A.9.2.5.4.1b]
point a vent starts plugholing, but not to assess the smoke
extract rate while a vent is plugholing.
There is therefore no experimentally validated method of
assessing the effect of plugholing on the rate of descent of a
smoke layer. A method has been published in BS 7346-5, Func­
where:
tional recommendations and calculation methods for smoke and heat
exhaust ventilation systems employing tim�dependent design fires.
z,; = height of smoke layer interface above the ba�e of the fire
t = time (sec)
A.9.2.4. 1 The mass flow rate through the vent is the product Q = total heat release rate
of gas density, velocity, and cross-sectional area of the flow in H = ceiling height above base of fire
the vent. The velocity follows from equating the buoyancy head A, = curtained area being filled with smoke (m2)
across the vent to the dynamic head in the vent, with considera­
tion of the pressure drop across the air inlets. The factor A.9.2.5.4.2.1 The response data in NfPA 72 assume extensive,
flat, horizontal ceilings.
r P:Ll7) / 7i! J 1;2 is quite insensitive to tempet·ature as long as
the smoke layer temperature rise, /',. 1: is not small. For exam­ This assumption might appear optimistic for installations
ple, assuming 1: = 294 K, tl1e factor varies tl1rough 0.47, 0.50, involving beamed ceilings. However, any delay in operation due
and 0.47 as the smoke layer temperature rise varies through to beams is at least partially offset by the opposite effect� of the
150 K, 320 K, and 570 K At a temperature rise of 60 K, the following:

2021 Edition
 ANNEX A 204-25

(1) Heat banking up under the ceiling because of draft A.9.2.5.4.4.2 Another program, DETACT-QS (DETector
cw-rains or walls ACTuation - Quasi Steady) [Evans and Stroup, 1985], is avail­
(2) The nearest vent or detector usually being closer to the able for calculating detection times of heat detectors, fusible
fire than the assumed, greatest possible distance links, and smoke detectors in fires of arbitrary fire growth.
DETACT-QS assumes that the detector is located in a large
Fusible links are commonly used as actuators for mechani­ comparunent with an unconfined ceiling, where there is no
cally opened heat and smoke vents. Where the response time accumulation of hot gases at the ceiling. Thus, heating of the
index (RTI) and fusing temperature of a fusible link are detector is only from the flow of hot gases along the ceiling.
known, and assuming that d1e link is submerged in the ceiling Input data consist of ceiling height, time constant or RTI of the
jet, the relationships described in NFPA 72 for heat-actuated detector, operating temperature, distance of the detector fi·om
alarm devices can be used to estimate the opening of a the plume centedine, and fire grmvth rate. The model calcu­
mechanical vent. lates detection times for smoke detectors (see 9.2.5.4.3) based
A.9.2.5.4.3.1 This requirement does not have a parallel in on the predecessor equations. Quasi-steady temperatures and
NFPA 72. Temperature rise for activation of smoke detectors velocities are assumed (i.e., instantaneously, gas temperatures
depends on the specific detector as well as the material under­ and velocities under the ceiling are assumed to be related to
going combustion. Limited data on temperature rise at detec­ the heat release rate as in a steady fire). Compared to DETACT­
tion have previously been recorded in the range of 2°C to T2, DETACT-QS provides a means of addressing fires that
42°C, depending on the detector/material combination cannot be approximated as t-squared fires. However, for
(Heskestad and Delichatsios, 1977). t-squared fires, DETACT-QS is less accurate than DETACT-T2
(if the pmjected fire growth coefficient is increased as de­
A.9.2.5.4.4. 1 A computer program known as DETACT-T2 scribed in 9.2.5.4.4.1 and A.9.2.5.4.4.1), especially for fast­
(DETector ACTuation - Time Squared) (Evans and Su-oup, growing fires.
1985) is available for calculating the detection times of heat
detectors or fusible links in continuous-growth, t-squared fires. A.IO.l Thet-e is an ISO standat-d for mechanical smoke extract
DETACT-T2 assumes the detector is located in a large compart­ (ISO 21927-3, Smoke and Heat Control Systems - Part 3: Specifica­
ment with an unconfined ceiling, where there is no accumula­ tion for powered smoke and heat exhaust ventilators) . The ISO stand­
tion of hot gases at the ceiling. Thus, heating of the detector is ard is technically equivalent to the European (EN) standard for
only from the flow of hot gases along the ceiling. Input data these products. Products that carry the CE mark, which is
consist of ceiling height, time constant or RTI of the detector, mandatory for sale of these product� within the European
operating temperamre, distance of the detector from plume Union, are subject to independent testing and ongoing factory
centet-line, and fire growth rate. The model calculates detec­ production cont rol by Notified Bodies appointed by national
tion times for smoke detectors (see 9.2.5.4.3) based on the pred­ governments. The standard is BS EN 12101-3, Smoke and Heat
ecessor equations. The predecessor equations assume complete Control Systems - Part 3: Specification joT powered smoke and heat
combustion of the test fuel used in the experiments used to exhaust ventilators.
develop the equations based on the actual heat of combustion: A.IO.l.l Where temperature differences of less than l l OOC
(230°F) are expected, vent flows might be ,-educed signifi­
cantly; therefore, consideration should be given to using
( )
[A.9.2.5.4.4.1]
powered exhaust. NFPA 92 should be consulted for guidance
-1).63
12
- - u __ o
..,- ....,- = . 59 -.!:._ for power venting at these lower temperatures.
( )
t::.1� /T, gH 1 H
A.l0.4 The sizing and spacing of exhaust fan intakes should
balance the following concerns:
where:
u = gas velocity at detector site (1) The exhaust intakes need to be sufficiently close to one
r = radius from fire axis another to prevent the smoke from cooling to the point
117� = gas tempet-ature rise from ambient at detectot­ that it loses buoyancy as it u-avels along the undet-side of
the ceiling to an intake and descends from the ceiling.
T. = ambient air temperature
This is particularly important for spaces where the length
g = acceleration of gravity
is greater than the height, such as shopping malls.
H = ceiling height (above combustibles)
(2) The exhaust intakes need to be sized and disu·ibuted in
However, DETACT-T2 can still be used, provided that the the space to minimize the likelihood of air beneath the
projected fire growth coefficient, a:w is multiplied by the factor smoke layet- ft-om being drawn through the layer. This
1.67. In addition, when DETACT-T2 is used, the outputs of heat phenomenon is called plugholing.
release rate at detector response from the program calculations
The objective of distributing fan inlets is therefore to estab­
must be divided by 1.67 in order to establish heat ,-elease rates
lish a gentle and generally tmifonn ,-are over the entire smoke
at detector response.
layer. To accomplish this, the velocity of the exhaust inlet
should not exceed the value determined from Equation A.10.4.

2021 Edition
204-26 SMOKE AND HEAT VENTLNG

For plugholing calculations, the smoke temperature should system could adversely affect the performance of the fire
be calculated as follows: suppression provided by ESFR sprinklers.
A.ll.3 Figure A. l l .3 shows the recommended spacing of
[A. l0.4] sprinklers with respect to the draft curtain locations.
A.l2.1 Regular inspection and maintenance is essential fat­
emergency equipment and systems that are not subjected to
their intended use for many years.
where:
A.l2.2 Various types of approved automatic thermal smoke
T = smoke layer temperature (°F)
and heat vents are available commercially. These vents fall into
1: = ambient temperatme (°F)
the following two general categories:
K = fraction of convective energy contained in the smoke layer
gases (1) Mechanically opened vents, which include spring-lift,
Q, = convective portion of heat release (Btu/sec) pneumatic-lift, or electric motor-driven vents
m = mass flow rate of the plume (lb/sec) (2) Thermoplastic drop-out vents, which include polyvinyl
Cp = specific heat of plume gases (0.24 Btu/lb-°F) chloride (PVC) or acrylic drop-out panels

A value of K = 0.5 is suggested unless more detailed informa­ Thermoplastic drop-out vents do not allow nondestructive
tion is available. operation.

A.l0.4.3 The plugholing equation of this paragraph is consis­ A.l2.3.1.4 Vents designed for multiple functions (e.g., the
tent with and derived from the scale model studies of Spratt entrance of daylight, roof access, comfort ventilation) need
and Heselden [1974]. The equation is also consistent with the maintenance of tl1e fire protection function that might be
recent study of Nii, Nitta, Harada, and Yamaguchi [2003] . impaired by the other uses. These impairments can include loss
of spring tension; racking or wear of moving parts; adverse
A.l0.4.4 The 1 factor of 1.0 applies to ceiling vents remote exterior cooling effects on the fire pwtection t-elease mecha-
from a wall. Remote is regarded as a separation greater than tw·o
times the depth of the smoke layer below the lower point of the
exhaust opening.
A.l0.4.5 The 1 factor of 0.5 is based upon potential flow
considerations for a ceiling vent adjacent to a wall. Vllhile 1
should vary smoothly from 0.5 for a vent directly adjacent to a
wall to 1.0 for a ceiling vent remote from a wall, the available
data do not support this level of detail in the requirements of
the standard.
A.l0.4.6 The 1 factor of 0.5 is used for all wall vents. Because
no data exist for wall exhausts, a value of 1 greater than 0.5
could not be justified.
A.l0.4.7 Noise due to exhaust fan operation or due to velocity
at the exhaust inlet should be limited to allow the fire alarm
signal to be heard.
A.ll.l Chapters 4 through 10 represent the state of technol­
ogy of vent and draft curtain board design in the absence of
sprinklers. A broadly accepted equivalent design basis for using
sprinklers, vents, and curtain boards together for hazard
control (e.g., life safety, property protection, water usage,
obscuration) is currently not available. Designers are c autioned
that the use of venting with automatic sprinklers is an area of
ongoing research to determine its benefit and effect in
cot�w1ction with automatic suppression. See Section F.3 for
more information.
� Storage racks
A.ll.2 Smoke and heat vents should be designed not to E2Lj = Storage racks
adversely impact the performance of the automatic spt-i nkler = Draft curtains
system. See 20.6.5 of NFPA 13. Testing and computer model
studies conducted to date that have addressed the interaction S = Sprinkler spacing in same direction
of smoke and heat vents have been limited to control mode Example: Sprinkler spacing is 10 ft (3 m) in both directions.
sprinklers. Because ESFR sprinklers have not been considered Minimum spacing between face of storage and draft curtain is 7.5 ft
in any such studies, use of the guidance in this document is not (2.3 m) so minimum aisle space at draft curtain greater than or equal
applicable to ESFR sprinklers. The RTI is considerably lower to 1 5 ft (4.6 m).
than, and the required water discharge per sprinkler is consid­ FIGURE A.ll.3 Recommended Sprinkler Spacing with
erably higher than, those of control mode sprinklers. There is Respect to Draft Curtain Locations.
concern that early operation of a smoke and heat venting

2021 Edition
 ANNEX B 204-27

nism; adverse changes in performance sequence, such as well-ventilated compartment fires with curtain boards and ceil­
premature heat actuation leading to opening of the vent; or ing vents actuated by heat-t·esponsive elements such as fusible
reduced sensitivity to heat. links or thermoplastic drop-out panels. Complete equations
and assumptions are presented. Phenomena taken into
A.I2.3.2.2 Inspection schedules should include provisions for account include the following:
testing all units at 12-month intervals or on a schedule based
on a percentage of the total units to be tested every month or (1) Flow dynamics of the upward-driven, buoyant fire plume
every t\vo months. Such procedures improve reliability. A (2) Growth of the elevated-temperature smoke layer in the
change in occupancy, or in neighboring occupancies, and in curtained compartment
materials being used could introduce a significant change in (3) Flow of smoke from the layer to the outside through
the nature or severity of corrosive atmosphere exposure, debris open ceiling vents
accumulation, or physical encumbrance and could necessitate (4) Flow of smoke below curtain partitions to building spaces
a change in the inspection schedule. adjacent to the curtained space of fire origin
(5) Continuation of the fire plume in the upper layer
A.I2.3.2.3 Recording and logging of all pertinent characteris­ (6) Heat transfer to the ceiling surface and the thermal
tics of performance allows t·esults to be compared with those of response of the ceiling as a function of radial distance
previous inspections or acceptance tests and thus provides a from the point of piume-ceiling impingement
basis for determining the need for maintenance or for modify­ (7) Velocity and temperature distribution of plume-driven
ing the ft·equency of the inspection schedule to fit the experi­ near-ceiling flows and the response of near-ceiling­
ence. deployed fusible links as functions of distance below the
A.l2.3.3.1 The same general considerations for inspection ceiling
that apply to mechanically opened vents also pertain to ther­ (8) Distance from plume-ceiling impingement
moplastic drop-out vents. The thermoplastic panels of these The theoq' presented here is the basis of the LAVENT
vents are designed to soften and drop out from the vent open­ computer program that is supported by a user guide, which is
ing in response to the heat of a fire. This makes an operational presented in Annex C, and that can be used to study parametri­
test after installation impracticable. Recognized fire protection cally a wide range of relevant fire scenat·ios [ 1-3] .
testing laboratories have developed standards and procedures
for evaluating d1ermoplastic drop-out vents, including factot·y B.2 Introduction. The space under consideration is a space of
and field inspection schedules. It is suggested that laboratory a plan area, A, defined by ceiling-mounted curtain boards with
recommendations be followed for the field inspection of such a fire of time-dependent energy relea5e rate, Q (t) , and with
units. open ceiling vents of total time-dependent area, A1r(t). The
A.l2.3.3.2 Thermoplastic drop-out vents utilize various types curtained area can be considered as one of several such spaces
of plastics such as PVC and acrylic. W'ithout the presence of in a large building compartment. Also, by specifYing that the
ultraviolet (UV) stabilizet·s, exposure to UV t·ays can cause curtains be deep enough, they can be d10ught of as simulating
degradation and failure of the d1ermoplasric component the walls of a single, uncurtained compartment. This annex
(dome). Indication of UV degradation includes yellowing, present5 the physical basis and associated mathematical model
browning, or blackening of the dome, as well as ct·acking or a for estimating the fire-generated environment and the
brittle texture of the dome. (This condition can prevent proper response of sprinkler links in curtained compartment fires with
operation of tl1e thermoplastic material; i.e., it will not operate ceiling vents actuated by heat-responsive elements such as fusi­
at its design activation temperature.) Corrective action requires ble links or thennoplastic drop-out panels.
replacing the thermoplastic dome with a dome having an The overall building compartment is assumed to have near­
equivalent thermal response. floor wall vents that are large enough to maintain the inside
A.l2.4.1.3 The whipping action of d1e cable on t·elease environment, below any near-ceiling smoke layet·s that could
presents a possibility of injury to anyone in the area. For this form, at assumed initial outside-ambient conditions. Figure
reason, the person conducting the test should ensure that all F.2(a) depicts the generic fire scenario for the space under
personnel are well clear of the area where whipping of the considet·ation. The assumption of large neat·-floor wall vents
cable might occur. necessitates that the modeling be restricted to conditions
where y, the elevation of the smoke layer interface, is above the
A.l3.1 Design documentation is critical to the proper installa­ floor elevation (i.e., y > 0). The assumption also has important
tion, operation, and maintenance of the smoke and heat vent implications with regard to the cross-ceiling vent pressure
systems. It forms the basis for evaluating the system's adequacy differential. This is the pressure differential that drives
to perform as intended if the building or its use is modified. elevated-tempemture upper-layet· smoke through the ceiling
Additional information on how to pt·epare design documenta­ vent� to the out�ide. Therefore, below the smoke layer (i.e.,
tion can be found in the SFPE Engineering Guide to Performance­ from the floor of the facility to the elevation of the smoke layer
Based Fire Pmtection. interface) , the inside-tcroutside hydrostatic pressure diffe ren­
tial exists at all elevations in the reduced-density smoke layer
Annex B The Theoretical Basis of LAVENT itself (higher pressure inside the curtained area, lower pressure
in the outside environment), the maximum differential occur­
77!is annex is not a part of the requirements of this NFPA document ring at the ceiling and across the open ceiling vents.
but is includedfor informationalpwposes only.
B.3 The Basic Equations. A twcrlayer, zone-type compartment
B.l Overview. This annex develops the physical basis and an fire model is used to describe the phenomena under investiga­
associated mathematical model for estimating the fire­ tion. As is typical in such models, the upper smoke layer of
generated environment and the response of sprinkler links in

2021 Edition
204-28 SMOKE AND HEAT VENTLNG

total mass, mu, is assumed to be uniform tn density, Pu. and Using Equation B.3c in Equation B.3a leads to
absolute temperature, 7�;-

The following time-dependent equations describe conserva­ [B.3h]

tion of energy, mass, and the perfect gas law in the upper dy lfu
smoke layet� dt A Cp/J.,.. 1:,.,
Conservation of energy,
if
[B.3a]
Y = Yrril and lfu � 0
or

0 < y > Y,u and lfu is arbitrary

Conservation of mass,
Because both of these conditions are satisfied, Equation B.3h
[B.3b] is always applicable.
dmu . The basic pwblem of mathematically simulating the gwwth
-- = mu
dt and properties of the upper layer for d1e generic Figure F.2(a)
scenario necessitates the solution of the system of Equation
B.3b and Equation B.3h for mu and y. When mu > 0, P u can be
[B.3c] computed from Equation B.3c according to the following:

[B.3i]
Perfect gas law,
A
Pu _
- b"um- y) ,. if. mu > 0
u
[B.3d]
Pu p and 7lj can be determined from Equation B.3e.
= constant = PuTu = P
R
<X
••
T
"' amb
R B.4 Mass Flow and Fnthalpy Flow Plus Heat Transfer.

That is, B.4.1 Flow to the Upper Layer from the Vents. Conservation
of momentum across all open ceiling vents as expressed by
Bernoulli's equation leads to the following:
[B.3e]
7: P
,u - ,"' """'
1 [B.4.Ia]
Pu
In the preceding equations, )',,;1 is the elevation of the ceiling
above the floor, R Cp-C11 is the gas constant, q, and �� are the
=

specific heats at a constant pt-essure and volume, respectively,

and p is a constant characteristic pressure (e.g., p.,..) at the
[B.4.lb]
floor elevation. In Equation B.3a, itu is the net rate of enthalpy
flow plus heat tt·ansfer to the upper layer and is made up of
flow components a� follows: it""' , from below the curtain;
itp�,.me , from the plume; it"'"' , from the ceiling vent; and the where:
component ifnT , the total heat transfer rate. V = the average velocity through all open vents
C = the vent flow coefficient (0.68) [ 4 ]
[B.3fj !1p,,.;1 = the cross-vent pressure difference
Fwm hydrostatics,

In Equation B.3b, thu is the net rate of mass flow to the

[B.4.lc]
upper layer with flow components; man-1 ' from below the
curtain; m,,,,., , from the plume; and 1n""" , fi-om the ceiling L'>P..u = Pu b = Yre�I) - P .u, ( y = Y,,;[)
•

vent.
= (P .u, - Pu )g( y,u - y)
•

[B.3g] where:
g = the acceleration of gravity

2021 Edition
 ANNEX B 204-29

Substituting Equation B.4.1c into Equation B.4. l b leads to

the desired m,.., result, as follows: [B.4.2c]

[B.4.ld]
0; i )' -
f
yJi• $ 0;
- -
0. 0054[( 1 - A.,)Q] y yfi• ; i f O < y yr., < l
which is equivalent to the equations used to estimate ceiling Lflrllilt Lfl<'Utl"
vent flow rates (see Equation 9.2.4.1 and Tefe-rences [5] and [61). 0. 071[( 1 - A., )Q.J"'
Using Equation B.4.ld, the desired q..,, result is as follows:
?h.,, =

[
x{ {,-- y1,, - L1�_) +0. 1 66( (1 - A., )Q J"T"
1+ E [( 1 - A., )Q.t'

l
[B.4.1e]
x ;
x{(y - )'Ji, - LJI�• ) + 0.166[(1 - A., ) Qr'T'"
B.4.2 Flow to the Layer from the Plume and Radiation from
the Fire. It is asswned that the mass generation rate of the fire if )' - )'"' ;:-: 1
is small compared to 1n,,, , the rate of mass of air enu·ained into Lfl(..l
,.

the plume between the fire elevation, Y;;··,., and the layer inter-
face, or compared to other mass flow rate components of mu .
where m,.,, is in kg/sec, Q is in k,J\1, an d y J;;,, Lflame are in m
,

It is also assumed that all of the m,.., peneu·ates the layer inter­ and where
face and entet·s the upper layer. Therefore,
[B.4.2d]
] 5
0.249[(1- A.' ) Q. 2 1
[B.4.2a]
0; if - 1 .02< 0
Dft,.

o .249 [(1 - t.. , ) Q r

5
Lfl, .
= 1---'�---''--- - 1 .02;
.
[B.4.2b]
Dft.. Dfi"'
.
0.249 (1 - A. Q2
The first term on the right side of Equation B.4.2b is the if [ , ) ] / 5 - 1 .02 :?: 0
enthalpy associated with 1h,,, , and >--,., in the. second term in Dft ,

Equation B.4.2b, is the effective fi·action of Q asswned to be

radiated isou·opically from the fire's combustion zone. where Q is in kW, D;;,.is in m, and
It is assumed that the smoke layer is relatively transparent
and d1at it does not participate in any significant radiation heat [B.4.2e]
u·ansfer exchanges. In particular, all of the >--,Q radiation is
0· 0054
assumed to be incident on the bounding surfaces of the E= ( ) - (0. 166) 51 3 = 0.02591682 . . . "" 0.026
compal"Unent. Therefore, the last term of Equation B.4.2b is 0.071
the net amount of enthalpy added to the upper layer from the
combustion zone and it� buoyancy-driven plume. Flaming fires In Equations B.4.2c through B.4.2e,
exhibit values fot· >--, of 0 < >--, < 0.6 (e.g., smallest values for Lfl""" is the fire's flame length.
small methane fires and highest values for large polystyrene
fires). However, for a hazardous fire involving a wide range of Dfi" is the effective diameter of the fire source (11JJl;;,/4 =
common groupings of combustibles, it is reasonable to approx­ area of the fire source).
imate flame radiation by choosing >-- e<: 0.35 [7].
E is chosen so that, analytically, the value of 1n,.., is exacdy
A specific plume enu·ainment model is necessary to continuous at the elevation y = Y;;.. + Lflam.-
complete Equations B.4.1 e and B.4.2a for 1iz1,,..� and iJp� . The
.....

following estimate for m,, [8, 9] is adopted as follows:

2021 Edition
204-30 SMOKE AND HEAT VENTLNG

B.4.3 Flow to the Layer from Below the Curtains. If the upper ment point is relatively far from the closest curtain or wall
layer interface, y, drops below the elevation of the bottom of smface (e.g., greater than a few fire-to-ceiling lengths). Under
the curtains, Y='' mass and enthalpy flows occur from the such circumstances, the ceiling jet-wall flow interactions are
upper layer of the cmtained area where the fire is located to relatively weak, and compared to the net rate of heat transfer
adjacent curtained areas of the overall building compartment. from the ceiling and near the plume-ceiling impingement
The mass flow rate is the result of hydrostatic cross-cm-tain point, the heat u-ansfer to the upper layer from all vertical
pressure differentials. Provided adjacent curtained areas are surfaces is relatively small.
not yet filled vvith smoke, this pressure diffe rence increases
Define \,,.'" as the fraction of Q that is transfen-ed by
lineady from zero at the layer interface to f"..p""'"' at y y,,.,,.
convection from the upper-layer gas ceiling jet to the ceiling
=

From hydrostatics, and to the vertical wall and curtain surfaces as follows:

[B.4.3a] [B.4.4]

ilp,,.,, = Pu (} = J,,,. ) - Pa•w ( y = Ymu)

= (p"""
' - Pu )g(y..,"' - y) Once the values of \,.," Q and iJm are determined from a
time-dependent solution to the coupled, ceiling jet-ceiling
Using Equation B.4.3a together with well-known vent flow material, convection-conduction problem, the task of deter­
relations (e.g., Equation 32 of reference [ 4] ), mNn, and q,,., mining an estimate for each component of ifu and mu in
can be estimated from the following: Equations B.3f and B.3g, respectively, is complete.
B.4.4.1 Properties of the Plume in the Upper Layer When Yfire <
[B.4.3b] y. Those instances of the fire elevation being below the inter­
face (i.e., when yfi,. < y) are considered het-e.

As the plume flow moves to the center of the upper layer,

the forces of buoyancy that act to drive the plume toward the
ceiling (i.e., as a result of relatively high-temperanu-e, low­
density plume gases being submerged in a relatively cool, high­
[B.4.3c] density ambient environment) are reduced immediately
because of the temperature increase of the upper-layer envi­
ronment over that of the lower ambient. As a result, the contin­
where L,,., is that length of the perimeter of the curtained ued ascent of the plume gases is less vigorous (i.e., ascent is at
areas of the fire origin that is connected to other curtained reduced velocity) and of higher temperature than it would be
areas of the overall building compartment. For example, if the in the absence of the layer. Indeed, some of the peneu-ating
curtained area is in one corner of the building compartment, plume flow \viii be at a lower temperature than 7�;- The upper­
then the length of its rwo sides coincident with the walls of the layer buoyant forces on this latter portion of the flow actually
compartment are not included in L,.,",. Because the generic retard and can possibly stop its subsequent t·ise to the ceiling.
vent flow configuration under consideration in this case is long A simple point-source plume model [10] is used to simulate
and deep, a flow coefficient for the vent flow incorporated into the plume flow, first immediately below or upstream of the
Equation B.4.3b is taken to be 1. interface and then throughout the depth of the upper layer
B.4.4 Heat Transfer to the Upper Layer. As discussed in B.4.3, itself.
where the fire is below the layer interface, the buoyant fire A plume above a point source of buoyancy [ 1 0 ] . where the
plume rises toward the ceiling, and all of its mass and enthalpy source is below the interface, will be considered to be equiva­
flow, m,�""" and 11� , are assumed to be deposited into the
..... lent to the plume of a fire (in the sense of having identical
upper layer. Having penetrated the interface, the plume mass and enthalpy flow rates at the interface) if the point­
continues to rise toward the ceiling of the curtained compart­ source su-ength is ( 1 - \,.) Q and the elevation of the equiva­
ment. A� it impinges on the ceiling surface, the plume flow lent source, y"'' satisfies the following·:
turns and forms a relatively high-temperature, high-velocity,
turbulent ceiling jet that flows radially out\vard along the ceil­
ing and u-ansfers heat to the relatively cool ceiling surface. The
[B.4.4.la]
. 1
,.. .1,g / 2 (y )51 2 . •t
ceiling jet is cooled by convection, and the ceiling material is m1�,... = 0. 2 1p
, - }'"' Q,,1 / 3
heated by conduction. The convective heat transfer rate is a
strong function of the radial distance from the point of plume­ In Equation B.4.4.1a, a dimensionless measure of the
�,
ceiling impingement and reduces rapidly with increasing su-ength of the fire plume at the intetface, is defined as follows:
radius. It is dependent also on the characteristics of the plume
immediately upsu-eam of ceiling impingement.
The ceiling jet is blocked eventually by the curtains, wall
[B.4.4.lb]

surfaces, or both. It then turns downward and forms vertical

surface flows. In the case of wall surfaces and very deep
curtains, the descent of these flows is stopped eventually by
upward buoyant forces, and they finally mix with the upper
layer. In this case, it is assumed that the plume-ceiling impinge-

2021 Edition
 ANNEX B 204-31

It should be noted that at an arbitrary moment of time on

the simulation of a fit-e scenario, rizl'l""" in Equation B.4.4.la, is [B.4.4.li]
a known value that is determined previously from Equations ., ( l - 1-, )Qcrm'
B.4.2a and B.4.2c. Q l + cr
=
. ,Using Equations B.4.4.la and B.4.4. l b to solve for y,1 and
Q
Yf ,
[B.4.4.lj]

[B.4.4.lc]

The fire and the equivalent source in the lower layer and the
continuation source in the upper layer are depicted in Figure
B.4.4. 1 , parts (a) through (c). Those times during a fire simula­
tion when Equation B.4.4.lf predicts a > 1 are related to states

[ ]
[B.4.4.ld]
31 2 of the fire environment in which the temperature distribution
. • 0.21(1 - I. , ) Q above 1:,.., of the plume flow, at the elevation of interface pene­
" . u-ation, is predicted to be mostly much larger than 7'u - 1:,..,.
Cp7 amb1n plum�
�=
Under such circumstances, the peneu-ating plume flow is still
very strongly buoyant as it enters the upper layer. The plume
As the plume crosses the interface, the fraction, m: , of continues to rise to the ceiling and to drive ceiling jet convec­
that is still buoyant relative to the upper-layer environ­
m.,,,.•., ,
tive heat transfer at rates that differ only slightly (due to the
ment and presumably continues to rise to the ceiling, enu-ain­
elevated temperature upper-layer environment) from the heat
ing upper-layer gases along the way, is predicted [ I l l to be as
transfer rates that could occur in the absence of an upper layer.
follows:
Conditions where Equation B.4.4.lf predicts a < 0 are rela­
ted to times during a fire scenario when the temperature of the
plume at the elevation of interface penetration is predicted to
[B.4.4.le]
0; if - 1 < (J $ 0 be uniformly less than 1-;;. Under such circumstances, the pene­
riz' = L04599cr + 0.36039l cr' tration plume flow is not positively (i.e., upward) buoyant at
' if cr > O any point as it enters the upper layer. Therefore, while all of
1.0 + l .37748cr + 0.36039lcr'
this flow is assumed to enter and mix with the upper layer, it is
predicted that none of it rises to the ceiling in a coherent
where the dimensionless parameter, o, is defined as follows:
plume (i.e., q,., = 0). For this reason, where a < 0, tl1e exis­
tence of any significant ceiling jet flow is precluded, along with
[B.4.4.lf] significant convective heat transfer to the ceiling sm-face 01- to
near-ceiling-deployed fusible links.
The preceding analysis assumes that )'f,, < y. However, at the
onset of the fire scenario, yfi,. < y = y,ei1 and a, a, and 1n' of
Equation B.4.4. l e through Equation B.4.4.1 h, which depend
[B.4.4.lg] on the indeterminate initial value of Tu, are themselves unde­
fined. T�e situation at t = 0 is properly taken into account if Q =

( 1 - .A,)
Q and

where CT = 9 . 1 1 5 and where Q:, is the value computed in [B.4.4.lk]

Equation B.4.4. ld. y�,. = )',1 at t = 0
...

The parameters necessary to describe plume flow continua­

tion in the upper layer (i.e., between y and y";1) are further
identified f l l l according to a point-source plume f l O l . It has B.4.4.2 General Properties of the Plume in the Upper Layer.
been determined that this plmne can be modeled qS being When the fire is below the interface, the results of Equations
driven by a nonradiating buoyant source of strength, loca­ Q' , B.4.4.1 i and B.4.4.lj allow the fire-driven plume dynamics in
ted a distance the upper layer to be described according to the point-source
plume model [ 1 0 1 . If the fire is at or above the interface (i.e.,
[B.4.4. lh] � y), then m,, m, = 0, q,,,.m,
Y!i•• .. (1 >--,) Q , and the point­
= -

source model is used once again to simulate t11e upper-layer

plume flow. All cases can be treated using the following modi­
below the ceiling in a downward-extended upper-layer envi­ fied versions of odginal Equations B.4.4.1i and B.4.4.lj:
ronment of tempet-atm·e, 7'u, and density, Pu· The relevant
parameters predicted [ 1 1 ] are as follows:

2021 Edition
204-32 SMOKE AND HEAT VENTLNG

�� r
layer
r Tu

Yceil
__.....
:-
upper
layer
f\
nded

r &o Iy

Ytire --
I
(a) Fire and flames in the (b) Equivalent plume in the (c) Continuation plume in the
lower layer lower layer extended upper layer
FIGURE B.4.4.1 Fire and Equivalent Source.

temperature, 1lj, where H is determined from Equations

B.4.4.1h and B.4.4.1j.
[B.4.4.2a]
The objective is to estimate the instantaneous convective
( 1 - A., )Qcrm· heat transfer flux from the upper-layer gas to the lower-ceiling
f
i yfi,. < y < )',.;,
Q' = (1 + cr ) surface, q;,v,L (T , t) , and the net heat transfer fluxes to the
( 1 - A., ) Q ; if yfl,. � Y or if y = }'rril up p er and lower ceiling surface of the ceiling, q;;(1· , t) and
q;:lT, t) , respectively. With this information, the time­
dependent solution for the in-depth thermal response of the
ceiling material can be advanced to subsequent times. Also,
lj:.,,_1. can be integrated over the lower-ceiling surface to obtain
the desired instantaneous value for iJn-r .
[B.4.4.2b]

In view of the assumptions of the relatively large distance of

the fire from walls or curtains and on the relatively smal.l contri­
bution of heat transfer to these vertical sm·faces, it is reasona­
ble to carry out a somewhat simplified calculation for iJ11-r .
Therefore, iJ11-r is approximated by the integral of qq ; v.t. over n

an effective cit·cular ceiling area, Aiff, with a diameter, Diff,

where Y<q• m: , a, and a are calculated fi-om Equations centered at the point of impingement as fol.l ows:
B.4.4.1c through B.4.4.1g.

B.4.5 Computing IJm· and the Thermal Response of the Ceil­ [B.4.5a]
ing. ''�There the fire is below the interface and the interface is · - A.
q1rr - Q. (t)
below the ceiling, the method used for calculating the heat
ronu

transfer from the plume-driven ceiling jet to the ceiling and the = -Jq;:,v.L (T, t)dA
thermal response of the ceiling is from reference [ 1 2 ] . This A

method was developed to u·eat generic, confined-ceiling, room o,;2

fire scenarios. As outlined in this method r 1 2 l , the confined "' -21t J q;:,v. I. ( 1· , t) T d1·
ceiling problem is solved by applying the unconfined ceiling
heat u·ansfer solution r 13-15] to the problem of an upper-layer
source in an extended upper-layer environment equivalent to The value Aiff = "i..Jliff/4 is taken to be the acntal area of the
Equations B.4.4.2a and B.4.4.2b. \'\Then the fire is about the curtained space, A, plus the portion of the vertical curtain and
interface, the unconfined ceiling methodology applies directly. wal.l surfaces estimated to be covered by ceiling jet-driven wall
flows. An estimate for this extended, effective ceiling surface
To use the methods in references [12-15], an arbiu·ary area is obtained [ 1 6 1 , where it is concluded with some general­
moment of time during the course of the fire development is ity that ceiling jet-driven wall flows peneu·ate for a distance of
considered. It is assumed that the temperature disu·ibution of approximately O.SH from the ceiling in a downward direction.
the ceiling material, 7� has been computed up to this moment Therefot·e,
and is known as a function of distance, Z, measured upward
fwm the bottom sm·face of the ceiling, and radial distance, T,
measured from the constant point of plume-ceiling impinge­ [B.4.5b]
ment. The equivalent, extended upper-layer, unconfined ceil­
ing flow and heat u·ansfer problen� is depicted in Figure B. A•f! = rrD2,8
4
4.4.1(c). It involves the equivalent Q' heat source from Equa­
tion B.4.4.2a located a distance, H, below the ceiling surface in = A + O.SH ( P - Lru,, ) + L0,,min [O.SH , ( y,,, - )''"'' )]
an extended ambient envimnment of density, Pu• and absolute
where P = the total length of the perimeter of the curtained
area.

2021 Edition
 ANNEX B 204-33

B.4.5.1 Net Heat Transfer Flux to the Ceiling's Lower Surface. where:
The net heat transfer flux to the ceiling's lower surface, q� , is
made by means of up to three components - incident radia- [B.4.5.lf]
.H

tion, qr'"Cr� ; convection, q;.,w, L ; and reradiation, iJ':.a.L - as

follows:

[B.4.5.la]

As discussed in B.4.4, the radiant energy from the fire, \,Q ,

[B.4.5.lg]

is a�sumed to be radiated isotropically from the fire with negli­

gible ,-adiation absNption and emission from the compartment
gases.

[B.4.5.lb]

In Equation B.4.5. ld, Pr is the Prandtl number (taken to be

The convective heat transfer flux from the upper-layer gas to 0.7), and in Equation B.4.5.1g, V u is the kinematic viscosity of
the ceiling's lower surface can be calculated [13, 14) as follows: the upper-l�yer gas, which is assumed to have the properties of
air. Also, Q;t , a dimensionless number, is a measure of the
strength of the plume, and ReH is a characteristic Reynolds
number of the plume at the elevation of the ceiling.
[B.4.5.lc]

q·conv,l.
" = hL (TAD -TS,L )
The following estimate for vu [ 17] is used when computing
ReH from Equation B.4.5. l g:
where:
' L = convective heat transfer flux from the upper-layer gas
q· «mv, '
to the ceiling s lower surface [B.4.5.1h]
h1. = a heat transfer coefficient
1�0 = the temperature that is measured adjacent to an adia­
batic lower-ceiling surface
1�.L = the absolute temperanu-e of the ceiling's lower sm-face
Equations B.4.5. l d and B.4.5. l e determine hL and 7�0 as
follows: Equations B.4.5. l c through B.4.5. l h use a value for 7"u. At t =
0, where it is undefined, Tu should be set equal to Tamb This
·
yields the cotTect limiting result for the convective heat u-ansfer
[B.4.5.ld]
to tl1e ceiling, specifically, convective heat transfer to tl1e
[
8.82Re�" Pr-21' 1- ( 5.0 - 0.284Re:2 ) (: )l initially ambient temperature ceiling from an unconfined ceil­
ingjet in an ambient environment.
A� ilie fire simulation proceeds, the ceiling's lower surface
ifO � .2:... < 0.2
H temperature, Ts.u initially at 1:,.b, begins to increase. At all
hi. = times, the lower-ceiling surface is assumed to radiate diffusely

( ) -1/2 - - 0.0771
�
to the initially ambient temperature floor surface and to

[,. }
;;
0.283Re-;:'Pr-21' � • exposed surfaces of the building contents. In response to this
H
- + 0.279 radiation and to the direct radiation from the fire's combustion
H zone, the temperatures of these surfaces also increase with
if0.2 :'> ­
,. time. However, for times of interest here, it is assumed that
H their effective temperature increases are relatively small
compared to the characteristic increases of 1�'1.L· Accordingly, at
a given radial position of the ceiling's lower surface, the net
[B.4.5.le] radiation exchange between the ceiling and floor-contents
14 9T surfaces can be approximated by d1e following:
10.22 - - '- ; if 0 $ ..2:... < 0.2
TAD -Tu H H
1'uQ;J13
8.39! (� } if0.2 :'> ­
H
1'

2021 Edition
204-34 SMOKE AND HEAT VENTLNG

q'� are assumed to be small enough so that conduction in the

ceiling is quasi-one-dimensional in space [i.e., T T(Z, t, T) 1 . =
[B.4.5.1i]
Therefore, the 1:\vo-dimensional thermal response for the ceil­
(
cr 7"'
amh - T4S,L ) ing can be obtained from the solution to a set of one­
dimensional conduction problems for the following:
-n

q.,mtl,t = 1 1
-+ - -- 1
EL Efi""''
[B.4.5.3a]
where a is the Stefan-Boltzmann constant and E1 and Efloor T (Z t) = T ( Z t·' 1· = T ) ·' n = 1 to Nmtt
11. ' ' n

are the effective emittance-absorptance of the ceiling's lower

surface and the floor and contents surfaces (assumed to be where N.ad is the number of discrete radial positions neces­
gray), respectively, both ofwhich are taken to be 1 . sary to obtain a sufficiently smooth representation of the over­
B.4.5.2 Net Heat Transfer Flux to Ceiling's Upper Surface. It all ceiling temperature distribution. The radial positions are r,
is assumed that the ceiling's upper surface is exposed to a rela­ depicted in Figure B.4.5.3.
tively constant-temperature far-field environment at Tomb· Characteristic changes in ceiling temperan1re will occur over
Therefore, the net heat transfer flux to this surface, tiu , is changes in r/H of the order of 1 [ 1 5 ] . Therefore, it is reasona­
ble to expect accurate results for the Equation B.4.5a integral
made up of 1:\vo components, convection, q';,,v,u , and reradia­ q';,,v,L by interpolating between values of q';,v, 1. calculated at
tion, r:""d,U , as follOWS: radial positions separated by T/ intervals of 0.1 to 0.2.
H
Using the preceding ideas, the following procedure for find­
ing the thermal response of the ceiling and solving for q';rr is
implemented:
[B.4.5.2a]

q U - q amv.U+ q nmti,U
If - , ,,,
(1) Because y,61 -yfirt is a measure of in the current problem
H
and D1/2 is a measure of the maximum value of T, N,od is
These can be estimated from the following:
chosen as several multiples of the following:

[B.4.5.2b]
[B.4.5.3b]

In this case, N.ad is chosen as the first integer equal to or

[B.4.5.2c]

.,
(
cr T4
amb
-7 1
�.S,U ) greater than the following:
q ,.,.,.�,�; = 1 1
- +--1
Eu EJar [B.4.5.3c]

where Ts,u is the absolute temperantre of the upper surface

of the ceiling, hu is a heat transfer coefficient, and Epn and E u Yuu - Yrn-e
are the effective emittance-absorptance of the far-field and
(2) One temperature calculation point is placed at 0 and r=
ceiling's upper surface (assumed to be gray) , respectively, both
the remaining N,.d calculation points are distributed with
of which are taken to be 1 .
uniform separation at and between 0.2( y";' - yfi,.) and T
r=
The value for hu to be used [18] is as follows: = DrJ/2, the latter value being the upper limit of the inte­
gral of Equation B.4.5a; that is,
[B.4.5.2d]
) 13
hlJ = 1 .65 (Tamb - TS.U 1
[B.4.5.3d]
1j =0
where hu is in WIm2, and 1:,,., and 7�w are in K 12 = 0 . 2(Ycril - yf.,., )
B.4.5.3 Solving for the Thermal Response of the Ceiling for
1
'
Drf!
=
iJm . The temperature of the ceiling material is assumed to be N.., 2
governed by the Fourier heat conduction equation. By way of 1;, = r,_1 + l'l.1· if 2 < n < N,.,
the lower-ceiling-surface boundary condition, the boundary
value problem is coupled to, and is to be solved together with, where
the system of Equations B.3b and B.3h.
Initially, the ceiling is taken to be of uniform temperature, [B.4.5.3e]
Tomb· The upper- and lower-ceiling surfaces are then exposed to
the radial- and time-dependent rates of heat o·ansfer, q�� and
q';. , determined from Equations B.4.5.2a and B.4.5. la, respec­
tively. For times of interest here, radial gradients of q�, and

2021 Edition
 ANNEX B 204-35

(3) The boundary value problems are solved for the N,.d B.5 Actuation of Vents and Sprinklers. It is an objective of this
temperature distributions, 1:,. At arbiu·aq' radius, r, these standard to simulate conditions in building spaces where ceil­
are indicated in the inset portion of Figure B.4.5.3. ing vents and sprinkler links can be acmated by the responses
(4) For any moment of time during the calculation, the lower of near-ceiling-deployed fusible links. The concept is that,
surface values of the 1�, are used to compute the con·e­ during the course of a compartment fire, a deployed link is
sponding discrete values of engulfed by the near-ceiling convective flow of the elevated­
temperature products of combustion and entrained air of the
fire-generated plume. As the fire continues, convective heating
[B.4.5.3f]
of the link leads to an increase in its temperature. If and when
its fuse temperature is reached, any devices being operated by
the link are actuated.
from Equation B.4.5. lc.
The near-ceiling flow engulfing the link is the plume-driven
(5) The if:,u.L distribution in r is approximated by interpo­
ceiling jet referred to previously, which transfers heat to the
lating linearly between the iJ':,u, L." . The integration indi­
lower-ceiling surface and is cooled as it traverses under the ceil­
cated in Equation B.4.5a is carried out.
ing from the point of plume-ceiling impingement. In the case
The procedure for solving for the 1� is the same as that used of relatively smooth ceiling configurations, assumed to be
in t·eference [ 1 5 ] . It requires the thickness, thermal conductiv­ representative of the facilities studied in this standard, the ceil­
ity, and thermal diffusivity of the ceiling materiaL The solution ing jet flows outward radially from the point of impingement,
to the one-dimensional heat conduction equation involves an and it� gas velocity and temperature distributions, Vq and Tq.
explicit finite difference scheme that uses an algorithm taken respectively, are a function of radius from the impingement
from references [ 19, 20]. For a given set of calculations, N s 20 point, 1� distance below the ceiling, z, and time, t.
equal-spaced nodes are positioned at the surfaces and through
Vents acntated by alternate means, such as thermoplastic
the thickness of the ceiling at evety radius position, r,. The
drop-out panels with equivalent performance characteristics,
spacing, BZ(see Figure B.4.5.3), of these is selected to be large
can also be modeled using LAVENT Refer to A.9. l .
enough (based on a maximum time step) to ensure stability of
the calculation. B.5.1 Predicting the Thermal Response of the Fusible Links.
The thermal response of deployed fusible links is calculated up
to their fuse temperamre, 1-., by the convective heating flow
model of reference [21 ] . It is assumed that the specific link is
positioned at a specified radius from the impingement point, r
/2 = rL, and distance below the lower-ceiling surface, z z1.. 1�- is
=
1----- rN rad = Deff
defined as the link's assumed, nearly uniform temperamre.
1----- 'n ----1-. Instantaneous changes in Yt.. are determined by the following:

[B.5.1]

dT1. ( TCJ ,I. - TL ) VCJ1 1,I.2

__

dt RTf

where Tq,�. and VCJ,L are the values of Vq and Tcp respectively,
evaluated near the link position, and where RTf (response time
qrerad, U qconv, U index), a property of the link and relative flow orientation, can
Eq. B.4.5.2c Eq. B.4.5.2b be measured in the "plunge test" [21, 221. The R11 for ordi­
nary sprinkler links ranges from low values of 22 (m·sec) 112 for
quick-operating residential sprinklers, to 375 (m·sec) 112 for

\! slower standard sprinklers [23]. The utility of Equation B.5. 1 ,

which has been shown in reference [24] to be valid typically
through the link-fusing processes, is discussed further in refer­
ence [23], where it was used to predict link response in a para­
metric smdy involving two-layer compartment fire scenarios.
Also, in the latter work, the link response prediction methodol­
ogy was shown to demonstrate favorable comparisons between
predicted and measured link responses in a full-scale, one­
room, open-doorway compartment fire experiment.

Q
·-

'�'s'. t? \;... ,
•"

q rad-fire
Eq. B.4.5.1i
Computing 1�- from Equation B.5.1 fm a dilfet·ent link loca­
tion necessitates estimates of Vq,r and Tq,L for arbitrary link
positions, rL and zL.
B.5.2 The Velocity Distributions of the Ceiling Jet. Outside of
Eq. B.4.5.1b the plume-ceiling impingement stagnation zone, defined
FIGURE B.4.5.3 Illustration of the Geometry for the
approximately by 1/H s 0.2, and at a given 1� Vq rises rapidly
Boundary Value Problems of the Temperature Distributions, from zero at the ceiling's lower surface, z 0, to a maximum,
=
T,., Through the Ceiling at Radial Positions r,. V,,., at a distance z 0.235, 6(1') being the distance below the
�

2021 Edition
204-36 SMOKE AND HEAT VENTLNG

ceiling where V/V,,., = 1/2 061. In this region outside the stag­
nation zone, Vq can be estimated [16) as follows:
0

(-s x-- J'17[1- z /(0.238) ]

[B.5.2a]
%
·ro z
.
V9 _ 7 0.238 8 ' -<--
I
0.238 <1- _ _z
v
•• ,
0·23 )arccosh(2'1') x [-z--1] }; if 1$ _z_
cosh-2{( 0.77 0.230
0.238 0.238

( �)-!.]
[B.5.2b]
v
�" = 0.85
FIGURE B.5.2 A Plot of Dimensionless CeilingJet Velocity
Distribution, Vc;/V.,ax, as a Function of z/0.23� per Equation
B.5.2a.

where Q;, is defined in Equation B.4.5.1g. V(i/V.nax per Equa­ region of the flow, between z = 0 and 0.236, the normalized
tion B.5.2a is plotted in Figure B.5.2. temperature distribution is approximated by a quadratic func­
tion of z/(0.236), with Tc; = 7�,� at z = 0 and 7 ; = T,,.,. dTq I dz =
'c

In the vicinity of near-ceiling-deployed links located inside 0 at z 0.236. Therefore, where 1"/H:<: 0.2,
=

the stagnation zone, the fire-driven flow is changing directions

from an upward-directed plume flow to an outward-directed

0 +2 [( 1-0 (--z )� [ ( z )' ]

[B.5.3a]
ceiling jet-type flow. There the flow velocity local to the link,
the velocity that drives the link's connective heat transfer,
involves generally a significant vertical as well as radial compo­
nent of velocity. Nevertheless, at such link locations, it is
s
0.238 - (1-0 --
s) 0.230 ' s
)
·

T - T !_ z
reasonable to continue to approximate the link response using __!L__! = if0$--$
Equation B.5.1 with VCJ estimated using Equations B.5.2a and
B.5.2b and with Hset equal to 0.2; that is,
-r/
0 =

T.... - Tu 0.231> 1
Vq ;i£1$ - z
v.� 0.2­31>
[B.5.2c]
r
ifO � - < 0.2 [B.5.3b]
H
T.s.L - Tu
0S = 0 (T(j = TS,L ) = ;,,.
J _ 7;
B.5.3 The Temperature Distribution of the Ceiling Jet. ;
Outside of the plume-ceiling impingement stagnation zone
(i.e., where H :?: 0.2) and at a given value of 1; Tq rises very
r/ It should be noted that 85 is negative when the cei.ling
rapidly from the temperature of the ceiling's lower surface, 7�.u surface temperature is less than the upper-layer temperature
at z = 0, to a maximum, 7"",..,,., somewhat below the ceiling (e.g., relatively early in a fire, when the original ambient­
surface. It is assumed that this maximum value of Tq occurs at temperature ceiling surface has not yet reached the average
the identical distance below the ceiling as does the maximum temperature of the growing upper layer). Also, 85 is greater
of Vc; (i.e., at z 0. 236). Below this elevation, T"c; drops with
= than 1 when the ceiling surface temperamre is gt-eater than
increasing distance from the ceiling until it reaches the upper­ 1�na.v· This is possible, for example, during times of reduced fire
layer temperamre, Tu. In this latter, outer region of the ceiling size when the fire's near-ceiling plume temperamre is reduced
jet, the shape of the normalized Tq disu·ibution, ( 7'c; - 7lj)/ significantly, pet-haps temporat-ily, Ji-om previous values, but the
( 7�"""'- Tv), has the same characteristics as that of Vc;,l V.nax· Also, ceiling surface, heated previously to relatively high tempera­
because the boundary flow is mrbulent, it is reasonable to esti­ tures, has not cooled substantially. Plots of e per Equation
mate the characteristic thicknesses of the outer region of both B.5.3a are shown in Figure B.5.3 for cases where e is < 0,
the velocity and temperature disu-ibutions as being identical, between 0 and 1, and > 0.
both dictated by the distribution of the turbulent eddies there. In a manner similar to the treaunent of Vc;f V.,a.,., for the
For these reasons, the dimensionless velocity and tempera­ purpose of calculating 7-;_, from Equation B.5.1, 85 is approxi­
mre distribution are approximated as being identical in the mated inside the stagnation zone by the description of Equa­
outer region of the ceiling jet flow, 0. 236 z. In the inner
$ tions B.5.3a and B.5.3b, with H set equal to 0.2 as follows:
r/

2021 Edition
 ANNEX B 204-37

[B.5.3c]
= ceiling jet temperature - upper layer temperature
1"
if 0 $ - $ 0.2
H 0
With the radial distribution for 15.�. and T(; already calculated
up to a specific time, only 7�"""' is needed to complete the
derived estimate from Equations B.5.3a through B.5.3c for the
ceiling jet temperature distribution. This estimate is obtained
by invoking conservation of enet·gy. Therefore, at an arbitrary ,.
outside the stagnation zone, the total rate of radial outflow of
enthalpy (relative to the upper-layer temperature) of the ceil­ Distance "Hor ceiling, low heat transfer
ing jet is equal to the uniform rat<; of enthalpy flow in the below
upper-layer portion of the plume, , less the integral (from
Q' ceiling "Cool" ceiling, high heat transfer
the plume-ceiling impingement prior to r) of the flux of
convective heat transfer from the ceiling jet to the ceiling
surface as follows:

[B.5.3d]

FIGURE B.5.3 Plots of Dimensionless CeilingJet

Temperature Distribution, 8, as a Function of zj0.231i per
!..'""") Q'; if 0.2 .:; ..!:... Equation B.5.3a for Cases Where 85 is <0, Between 0 and 1,
= (1-
1-i and >O.

A�"" is the fraction of Q' transferred by convection to the

ceiling fi-om the point of ceiling impingement to r as follows: current model equations is to evaluate these su·ategies within
the context of the developing fire environment. For example,
one of the simplest sU·ategies [91 assumes that all vents
[B.5.3e] deployed in the specified curtained area are opened by what­
ever means at the onset of the fire. In general, A1, will be time­
21t] if�anv.t.(r,t)1· dr dependent. To the extent that a strategy of vent opening is
A.'ronu(1· ) = o_
___, --:- - - dependent directly on the fusing of any one or several
Q' deployed fusible links, the location of these Links and their
characteristics (i.e., likely spacings from plume-ceiling impinge­
In Equations B.5.3d and B.5.3e, Q' has been calculated ment, distance below d1e ceiling, and d1e RTI) and the func­
previously in Equation B.4.4.2a. Also, the integral on the right­ tional relationship between link fusing and Av need to be
hand sides of Equations B.5.3d and B.5.3e can be calculated by specified. These matters can be examined in the context of
approximating q�,.,,.J.(r,t) , as shown in Equation B.5.3e, as a diffet·ent solutions to the overall problem by exercising pat·a­
linear function of ·r between previously calculated values of meu·ically the LAVENT computer program [2] , which imple­
qttmv,L (r -
- rn' t) .
.
ments all the model equations provided in this annex.
The integral on the left-hand side of Equation B.5.3d is B.5.5 Concluding Remarks - A Summary of Guidelines,
calculated using Vr;� of Equations B.5.2a and B.5.3b and 7'c; of Assumptions, and Limitations. The theory presented here is
Equations B.5.3a and B.5.3b. From this, the desired distribu­ the basis of LAVENT, a user-friendly computer program [2]
tion for 7�""·' is determined as follows: that is supponed by a user guide [3] and that can be used to
study parametrically a wide range of relevant fire scenarios.
[B.5.3f] The assumptions made in the development of the set of

(T JNfrt
-T. ) = 2.6(1- 1..' ) ..:_
u (
M ,Io!
( )
H
"
· "'
Q.""'T
H u �L
-0.090(T. - T )·
. . u '
model equations limit fire scenarios ot· aspects of fire scenat·ios
that can be simulated and studied with confidence. A summary
of guidelines and assumptions that characterize what are
0.2 .:; ..!:... perhaps the most critical of these limitations follows. These are
the result of explicit or implicit assumptions necessary for valid
if
1-i
application of the variety of submodels introduced throughout
The result of Equation B.5.3f, together with Equations B.5.3a this work.
and B.5.3b, represents the desired estimate for 7'cl" This and
the estimate derived from Equations B.5.2a through B.5.2c for L and Ware the length and width, respectively, of d1e plan
Tq are used to calculate 7�. fi·om Equation B.S. l . area of the curtained space. Simulated configurations should
be limited to those with aspect ratios, L/W. that are not much
B.5.4 Dependence of Open Vent Area on Fusible-Link-Actu­ different from I (e.g., 0.5 .:; L/W< 2). Also, in such configura­
ated Vents. As discussed, the influence of ceiling vent action tions, the fire should not be too close to or too far from the
on the fit·e-generated equipment is dependent on the active walls [e.g., the fire should be no closer to a wall than ()',.;1 -
area of d1e open ceiling vents, Av. A variety of basic vent open­ J'ft,) /2 and no fard1er tl1an 3(y,,.u -yfi,)].
ing design strategies is possible, and a major application of the

2021 Edition
204-38 SMOKE AND HEAT VENTLNG

The curtain boards should be deep enough to satisfy (Yail - elevation, and especially if Equation B.4.3a predicts a flatne
)'a.,1) � 0.2 (y"" - )fi,.), unless the equations and the standard are height that reaches the ceiling.
used to simulate an unconfined ceiling scenario where (y..,1 -
= 0.
)'a.,,)
It is assumed that tl1e smoke is relatively transparent and that
the rate of radiation absorbed by or emitted from the smoke
The ceiling of the curtained space should be relatively layer is small compared to the rate of radiation o-ansfer from
smooth, with promberances having depths significantly less the fire's combustion zone. The assumption is typicaLly u-ue,
than 0.1 (y,.u- )fi,). Except at the locations of the curtain boards, and a simulation is valid at least up to those times that the phys­
below-ceiling-mounted barriers to flow, such as solid beams, ical features of d1e ceiling can be discerned visually from d1e
should be avoided. Ceiling surface protuberances near to and floor elevation.
upsu-eam of fusible links (i.e., between the links and the fire)
should be significantly smaller than link-to-ceiling distances. It should be emphasized that the preceding limitations are
intended only as guidelines. Therefm-e, even when the chat-ac­
Wv is the width, that is, the smaller dimension of a single ceil­ teristics of a particular fire scenario satisfy these Limitations, the
ing vent (or vent cluster). If vents are open, the prediction of result� should be regarded with caution until solutions to the
smoke layer thickness, Yuu - y, is reliable only after the time tl1at overall model equations have been validated by a substantial
(Ycrit - y)!Wv is greater tl1a11 1. (For smaller layer depths, body of experimental data. Also, where a fire scenario does not
"plugholing" flow through the vents could occur, leading to satisfy the preceding limitations but is close to doing so, it is
possible significat1t inaccumcies in vent flow estimates.) Note possible that the model equations can still provide useful quan­
that this places an additional Limitation on the minimum depth titative descriptions of the simulated phenomena.
of the curtain boards [i.e., (y"#- Ycw·1)/Wvshould exceed 1].
B.6 References for Annex B.
At all times during a simulated fire scenario, the overaLl
building space should be vented to the outside (e.g., through 1. Cooper, L. Y "Estimating the Environment and the
open doorways). Response of Sprinkler Links in Compartment Fires with Draft
Curtains and Fusible Link-Acntated Ceiling Vents," Fire Safety
In this ,-egard, compared to the open ceiling vent� in the joumal 16:37-163, 1990.
cw-tained compartment, the area of tl1e outside vents must be
large enough such that the pressure drop across the outside 2. LAVENT softv;are, available from National Institute of
vents s i small compared to the pressure drop across ceiling Standards atld Technology, Gaithersburg, MD.
vents. For example, under near-steady-state conditions, when 3. Davis, W. D. and L. Y. Cooper. "Estimating the Environ­
the rate of mass flow into the outside vents is approximately ment and the Response of Sprinkler Links in Compat-tment
equal to the rate of mass outflow from the ceiling vents, the Fires with Draft Curtains and Fusible Link-Acntated Ceiling
outside vent area must satisfY (A11 .,/Av)2( 7'u/ 7:,,;) 2 >> 1, or,
•
Vents - Pat-t II: User Guide for the Computer Code LAVENT,"
more conservatively and independent of 10, (Av ...lA11) 2 >> 1 .
•
NISTIR 89-4122, National Instin1te of Standards and Technol­
The latter criterion will always be t·easonably satisfied if A1.,jA11 ogy, Gaithersburg, MD, August 1989.
> 2. Under flashover-level conditions - say, when Tu I 1:mh = 3
- the former criterion will be satisfied if ( 3A v ../ A11) 2 » 1 -
•
4. Emmons, H. W. "The Flow of Gases Through Vents,"
say, if A1.0.,1 = A11, or even if A11,., is somewhat smallet- than A1, Harvard University Home Fire Project Technical Report
No. 75, Cambridge, MA, 1987.
The simulation assumes a relatively quiescent outside envi­
ronment (i.e., vvithout any wind) and a relatively quiescent 5. Thomas, P. H., et a!. "Investigations into the Flow of Hot
inside environment (i.e., remote from vent flows, under-curtain Gases in Roof Venting," Fire Research Technical Paper No. 7,
flows, ceiling jets, and the fire plume) . In real fire scenarios, HMSO, London, 1963.
such an assumption should be valid where the characteristic 6. Heskestad, G. "Smoke Movement and Venting," Fire Safeyt
velocities of actual flows in these quiescent environments are joumal l l :77-83, 1986.
much less than the velocity of the fire plume near its ceiling
impingement point (i.e., where the characteristic velocities are 7. Cooper, L. Y. "A Mathematical Model for Estimating Avail­
much less than V:nax of Equation B.5.2b). It should be noted able Safe Egress Time in Fires," FiTe and Matmials 6(3/4): 135-
that, for a given fire su-ength, Q, this latter assumption places a 144, 1982.
restriction on the maximum size of ()'au - YJiw) , which is a meas­
ure of H, since V, , is approximately proportional to (y"" -
••.
8. Heskestad, G. "Engineering Relations for Fire Plumes,"
J'Ji,.)-113. Fire Safetyjouma/7:25-32, 1984.

In configurations where smoke flows below curtain parti­ 9. Hinkley, P. L. "Rates of 'Production' of Hot Gases in Roof
tions to adjacent curtained spaces, tl1e simulation is valid only Venting Experiments," Fi:re Safetyjouma/ 10:57-64, 1986.
up to the time that it takes for atly one of the adjacent spaces to 10. Zukoski, E. E., T. Kubota, and B. Cetegen. Fin: Safety jout·­
fill with smoke to tl1e level of the bottom of the curtain. vVhile na/ 3:107, 1981.
it is beyond the scope of this standard to provide any general
guidelines for this limiting time, the following rule can be 1 1 . Cooper, L. Y "A Buoyant Source in the Lower of Two,
useful where all curtained spaces of a building at-e similat- and Homogeneous, Stably So-atified Layers," 20th International
where the fire is not growing too rapidly: The time to fill an Symposium on Combustion, Combustion Instimte, University
adjacent space is of the order of the time to fill the original of Michigan, Ann Arbor, MI, pp. 1567-1573, 1984.
space.
The reliability of the simulation begins to degt·ade subse­
quent to tl1e time that the top of the flame penetrates the layer

2021 Edition
 ANNEX B 204-39

12. Cooper, L. Y "Convective Heat Transfer to Ceilings Dif1 = effective diameter of A11
Above Enclostu·e Fires," 19th Symposium (International) on
Combustion, Combustion Instimte, Haifa, Israel, pp. 933-939, Dfi,. = effective diameter of fire source ( nD�,. I 4 = area of fire
1982. source)
13. Cooper, L. Y "Heat Transfer from a Buoyant Plume to an g= acceleration of gravity
Unconfined Ceiling," journal of Heat Transfer 104:446-451, H = distance below ceiling of equivalent source
August 1982.
ii = characteristic heat transfer coefficient
14. Cooper, L. Y, and A. Woodhouse. "The Buoyant Plume­
Driven Adiabatic Ceiling Temperamre Revisited," joumal of hv hu = lower-, upper-ceiling surface heat transfer coefficient
Heat 11-an.ifer l 08:822-826, November 1986. L = characteristic length of the plan area of curtained space
15. Cooper·, L. Y , and D.W. Stroup. "Thermal Response of L'"n' = length of the perimeter of A connected to other
Unconfined CeiJjngs Above Growing Fires and the Importance curtained areas of the building
of Convective Heat Transfer," journal of Heat Transfer 109:172-
178, February 1987. Lfla"" = flame length
16. Cooper, L. Y "CeilingJet-Driven Wall Flows in Compart­ 1h'""' = mass flow rate from below cttrtain to upper layer
ment Fires," Combustion Science and Technology 62:285-296, 1988. 1h.,., = rate of plume mass entrainment between the fire and
17. Hilsemath, ]. "Tables of Ther-mal Properties of Gases," the layer interface
Circular 564, National Bureau of Standards, Gaithersburg, MD, 1npl,.,
November 1955. = mass flow rate of plume at interface
18. Youse£� W. W., J. D. Tarasuk, and V-l J. McKeen. "Free mu = total mass of the upper layer
Convection Heat Transfer from Upward-Facing, Isothermal, mu = net mass flow r·ate to upper layer
Horizontal Surfaces," joumal of Heat Tmn.ifer 104:493-499,
August 1982. m,,.,,, = mass flow rate through ceiling vents to upper layer
19. Emmons, H. W. "The Prediction of Fire in Buildings," N = number of equal-spaced nodes ilirough the ceiling
17th Symposium (International) in Combustion, Combustion N,ad = number of values of 1·,
Institute, Leeds, UK, pp. l l01-l l l l , 1979.
P = length of perimeter of single curtained area
20. Mitler, H. E., and H.W. Emmons. "Documentation for
the Fiftl1 Harvard Computer Fire Code," Harvard University, Pr = Prandtl number, taken to be 0.7
Home Fire Project Technical Report 45, Cambridge, MA, 1981.
p = pressure
21. Heskestad, G., and H. F. Smith. "Investigation of a New
Sprinkler Sensitivity Approval Test: The Plunge Test," Technical Pu, Pamh = pressure in upper-layer, outside ambient
Report Serial No. 22485, RC 76-T-50, Factory Mutual Research Q = energy release rate of fire
Corp., Norwood, MA, 1976.
Q' = strength of continuation source 111 extended upper
22. Heskestad, G. "The Sprinkler Response Time Index layer
(RTI)," Paper RC-81-Tp-3 presented at the Technical Confer­
ence on Residential Sprinkler Systems, Factory Mutual Q;1 = dimensionless strength of plume at ceiling
Research Corp., Norwood, MA, April 28-29, 1981. Q.� = dimensionless strength of plume at interface
23. Evans, D. D. "Calculating Sprinkler Actuation Times in q ;,,v,vlf:,v.u = convective heat u·ansfer flux to lower-, upper-
Compartments," Fire Safetyjoumal 9:l 47-l55, 1985. ceiling surface
24. Evans, D. D "Characterizing the Thermal Response of q:lllv,L,,v = q:(IIW,/.( 1� = 1;1 ,t)
Fusible Link Sprinklers," NBSIR 81-2329, National Bureau of
Standards, Gaithersburg, MD, 1981. ita.., = enthalpy flow rate from below curtain to upper layer
B.7 Nomenclature for Annex B. iJm· = heat transfer rate to upper layer
A = plan ar·ea of single curtain space iJ1,,m, = entl1alpy flow rate of plume at interface
A,ff = effective area for heat transfer to the extended lower- iJ,.t f
..
, = radiation flux incident on lower surface of ceiling
ceiling surface, nD,,j
1 I4
q;M·att,t. ,iJ�...d. u = reradiation flux to lower, upper surface of
Av = total area of open ceiling vents in cm·tained space ceiling
Av,,.1 = total area of open vents to outside exclusive of Av izu = net enthalpy flow rate plus heat u·ansfer rate to upper
layer
C = vent flow coefficient (0.68)
lf'ulf� = net heat u·ansfer fluxes to upper-, lower-ceiling
CP = specific heat at constant pressure
surface
C.r = 9.115, dimensionless constant in plume model
iJ,,.,, = enthalpy flow rate through ceiling vent to upper layer
Cv = specific heat at constant volume

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204-40 SMOKE AND HEAT VENTLNG

R = gas constant, C1, - Cv A, = fraction of Q radiated from combustion zone

ReH = Reynolds number of plume at ceiling elevation A'""" = fi·action of Q transferred by convection from upper
layer
RTf= response time index
"A;""" = fi·action of Q' transferred to the ceiling in a circle of
T= radial distance from plume-ceiling impingement t·adius, r, and centered at r = 0, Equation B.5.3e
1·1. = T at link
vu = kinematic viscosity of upper-layer gas
T,. = discrete values ofT Pu, Pamb = density of upper-layer, outside ambient
T= absolute temperature of ceiling material a = dimensionless variable, Equation B.4.4.1e
1�0 = adiabatic lower-ceiling surface tempet·ature
Tq = temperature diso·ibution of ceilingjet gas Annex C User Guide for the LAVENT Computer Code

Tq,L = Tq at link This annex is not a paTt of the requi·rements of this NFPA document
but is includedfo1· informational pwposes only.
1�nax (t) = Ts.1 (T= O,t) = T (Z= O,t, r = 0)
C.l Overview. This annex is a user guide for the LAVENT
1�.L• 1�u = absolute temperature of lower-, upper-ceiling computer code (Link-Actuated VENTs), Version l . l , and an
surface associated graphics code called GRAPH. As discussed in
Section 9.3 and in Annex B, LAVENT has been developed to
1�. 1.,. (t) = 1���- (r= r,t) = 1�, (Z= O,t, T= r.) simulate the environment and the response of sprinkler links
1�1, 1:,b = absolute temperature of upper-layer, outside ambi­ in compartment fires with curtain boards and fusible-link-acnt­
ent ated ceiling vents. Vents actuated by alternative means such as
thermoplastic drop-out panels with equivalent performance
1: = T (Z, t T = r.) characteristics can also be modeled using LAVENT. Refer to
t = time Al.l.l.
V = average flow velocity through all open vents A fire scenario simulated by LAVENT is defined by the
following input parameters:
V = chamcteristic value of Vq ( 1 ) Area and height of the curtained space
Vq = velocity distribution of ceiling jet gas (2) Separation distance from the floor to the bottom of the
curtain
VcJ,l. = Vq at link (3) Length of the curtain (A portion of the perimeter of the
curtained space can include floor-to-ceiling walls.)
V.nax = maximum value of Vq at a given r (4) Thickness and properties of the ceiling material (density,
W = characteristic width of plan area of curtained space thermal conductivity, and heat capacity)
(5) Constants that define a specified time-dependent energy
Wv = width of a single ceiling vent (or vent cluster) release rate of the fire
y, y";�> Yc'"'' )�q• YJi•• = elevation of smoke layer interface, ceiling, (6) Fire elevation
bottom of curtain, equivalent source fire above floor (7) Area or characteristic energy release rate per unit area of
the fire
)'�""' = elevation of plume continuation point source in (8) Total area of ceiling vents whose openings are actuated by
extended upper layer above floor a single fusible link (Multiple vent area/link system
Z= distance into the ceiling, measured from bottom surface
combinations may be permitted in any particular simula­
tion.)
z, z1• = distance below lower-ceiling surface, z, at link (9) IdentifYing numbers offusible links used to acntate single
spt·inkler heads or groups of sprinkler heads (Multiple
Q � 1"u/1:mb sprinkler links are permitted in any particular simula­
T = ratio of specific heat, Cp/Cv tion.)
t:,p,_11 = cross-vent pressure difference The characteristics of the simulated fusible links are defined
by the following input parameters:
t:,p0.,1 = cross-curtain pressure diffet·ence ( 1 ) Radial distance of the link from the fire-ceiling impinge-
5 = value of z where Vq � V..a.J2 ment point
(2) Ceiling-link separation distance
5Z = distance between nodes through the ceiling thickness (3) Link fuse temperature
E = constant, Equations B.4.2c and B.4.2e ( 4) The response time index (RTI) of the link
Ev Eu, Eflaa, E1., = emittance-absorptance of lowet� upper, For any particular run of LAVENT, the code outputs a
flom� and far-field gray surfaces, all taken to be 1 summary of the input information and simulation results of the
calculation, in tabular form, at uniform simulation time inter­
8 = normalized, dimensionless ceilingjet temperature distl'i­ vals requested by the user. The output results include the
bution, ( 1cr 1"u) I ( T.,ax - 1�;) following:
88 = 8 at lower-ceiling surface, ( 1S,L - Tu)/ (T..a.,.
-
Tu) (1) Tern perature of the upper smoke layer

2021 Edition
 ANNEX C 204-41

(2) Height of the smoke layer interface Fusible links that are designed to acmate d1e opening of ceil­
(3) Total mass in the layer ing vents and the onset of waterflow through sprinklers are
( 4)Fire energy release rate deployed at specified distances below the ceiling and at speci­
(5) Radial distributions of the lower-ceiling surface tempera­ fied radial distances from the plume-ceiling impingement
ture point. These links are submerged within the relatively high­
(6) Radial distribution of heat transfer rates to the lower- and temperature, high-velocity ceilingjet flow. Because the velocity
upper-ceiling surfaces and temperature of the ceiling jet vary with location and time,
(7) The temperature for each link and the local velocity and the heat u-ansfer to, and time of fusing of, any particular link
temperature of the ceilingjet design also vary.
This annex explains LAVENT using a series of exercises in The fusing of a ceiling vent link leads to the opening of all
which the reader reviews and modifies a default input data file vents "ganged" to that link. Once a ceiling vent is open, smoke
that describes vent and sprinkler acmation during fire growth flows out of the curtained space. Again, as when smoke flows
in an array of wood pallets located in a warehouse-type occu­ below the curtains, growth of the upper-layer thickness is retar­
pancy. Results of the default simulation are discussed. ded.
LAVENT is written in Fortran 77. The executable code oper­ The fusing of a sprinkler link initiates the flow of water
ates on IBM PC-compatible computers and needs a minimum through the sprinkler. All of the described phenomena, up to
of 300 kilobytes of mem01-y. the time that waterflow through a spdnkler is initiated, are
simulated by LAVENT. Results cannot be used after water
C.2 Introduction - The Phenomena Simulated by LAVENT.
begins to flow through a sprinkler.
Figure C.2 depicts the generic fire scenario simulated by
LAVENT. This scenario involves a fire in a building space with C.3 The Default Simulation. The use of LAV ENT is discussed
ceiling-mounted curtain boards and near-ceiling, fusible-link­ and is illusu-ated in the following paragraphs where exercises in
actuated ceiling vents and sprinklers. The curtained area can reviewing and modifying the LAVENT default-simulation input
be considered as one of several such spaces in a single large file are provided. To appreciate the pmcess more fully, a brief
building compartment. By specifYing that the curtains be deep description of the default simulation is presented at the outset.
enough, they can be thought of as simulating the walls of a
single uncurtained comparunent that is well-ventilated near the Note that, as explained in Section C.4, the user can choose
floor. to mn LAVENT using either English or metric units. The
default simulation uses US customary units. The example in
The fire generates a mixture of gaseous and solid-soot Annex D uses meu-ic units.
combustion products. Because of high temperature, buoyancy
forces drive the products upward toward the ceiling, forming a The default scenario involves an 84 ft x 84 ft (25.6 m x
plume of upward-moving hot gases and particulates. Cool gases 25.6 m) curtained compartment [7056 ft2 (655 m2 ) in area]
are laterally enu-ained and mixed with d1e plume flow, t·educ­ with the ceiling located 30 ft (9.1 m) above the floor. A curtain
ing its temperature as it continues its ascent to the ceiling. board 15 ft (4.6 m) in depth completely surrounds and defines
the comparunent, which is one of several such comparunents
When the hot plume flow impinges on the ceiling, it spreads in a larger building space. The ceiling is constructed of a relac
under it, forming a t-elatively thin, high-temperature ceiling jet. tively d1in sheet-steel lower surface that is well insulated from
Near-ceiling-deployed fusible links engulfed by the ceiling jet above. [See Figwt! C.3(a).]
are depicted in Figure C.2. There is reciprocal convective cool­
ing and heating of the ceiling jet and of the coolet- lower­
ceiling surface, respectively. The lower-ceiling surface is also
heated due to radiative u-ansfer from the combustion zone and Ceiling jet
cooled due to reradiation to the floor of the compartment. The
compartment floor is assumed to be at ambient temperature.
The upper-ceiling surface is cooled as a result of convection
and radiation to a far-field, ambient temperature environment.
When the ceiling jet reaches a bounding vertical curtain
board or wall surface, its flow is redistributed across the entire
curtained area and begins to form a relatively quiescent smoke
layer (now somewhat reduced in temperature) that submerges
the continuing ceiling jet flow activity. The upper smoke layer
grows in thickness. Away from bounding surfaces, the time­
dependent layer temperamre is assumed to be relatively
uniform throughout its thickness. It should be noted that the
thickness and temperature of the smoke layer affect the upper­
plume characteristics, the ceiling jet characteristics, and the Distance
below
heat-transfer exchanges to the ceiling. ceiling
If the height of the bottom of the smoke layer drops to the
bottom of the curtain board and continues downward, the
smoke begins to flow below the curtain into the adjacent
curtained spaces. The gt-owth of the upper layer is t-etarded. FIGURE C.2 Fire in a Building Space with Curtain Boards,
Ceiling Vents, and Fusible Links.

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204-42 SMOKE AND HEAT VENTLNG

The curtained compartment has four uniformly spaced associated links, 1:\vo are closest and equidistant to the fire­
48 ft2 ( 4.5 m2 ) ceiling vents with a total area of 192 ft2 ( 18 m2 ) , plwne axis at mdial distances of 6 ft ( 1 .8 m). Figure C.3(a)
or 2.7 percent of the compartment area. Opening of the ceil­ shows that the second and third closest groups of sprinklers
ing vents is acntated by quick-response fusible links with RTis and links are at radial distances of 13.4 ft ( 4.1 m) (four sprin­
of 50 (ft·sec) 112 [28 (m·sec) 112 ] and fuse temperatlll -es of 165°F klers and links) and 18 ft (5.5 m) (1:\vo sprinklers and links). In
(74°C). The links are located at the centers of the vents and the default calculation, the opening of each of the four vents
0.3 ft (0.09 m) below the ceiling surface. occurs, a11d the flow out of the vents is initiated at the simula­
ted time of fusing of their associated links. Also simulated in
Fusible-link-actuated sprinklers are deployed on a square the default calculation is the thermal response, including time
grid with 12 ft (3.7 m) spacing between sprinklers. The links offusing, of the pair of sprinkler links closest to the fire.
have RTis of 400 (ft·sec) 112 [2.2 (m·sec) 112 l and fuse tempera­
tures of 165°F (74°C). The spt-inklers and Links are mounted As a final specification of the fit-e, it is asswned that the char­
1 ft (30.1 em) below the ceiling surface. acteristic elevation of the fire remains at a fixed value, 2.5 ft
(0.8 m) above the floor, at the initial mid-elevation of the array
The simulation fire involves four abutting 5 ft ( 1 .5 m) high of combustibles. For the purpose of the default calculation, the
stacks of 5 ft x 5 ft (1.5 m x 1.5 m) wood pallets. The combined simulation is carried out to t = 400 seconds, with data output
grouping of pallets makes up a combustible array 10 ft x 10 ft every 30 seconds.
(3.1 m x 3.1 m) f100 ft2 (9.3 m2 ) in area] on the floor and 5 ft
( 1 .5 m) in height. It is assumed that other combustibles in the Having described the default simulation, the procedme for
curtained compartment are far enough away from this array getting started and using LAVENT follows.
that they cannot be ignited in the time interval to be simulated.
C.4 Getting Started. The executable code, LAVENT.EXE, is
The total energy release rate of the simulation fire, Q , found on the floppy disk. Before using it, backup copies should
assumed to grow from ignition, at time t = 0, in proportion to be made. If the user has a hard drive, a separate directory
P. According to tJ:te guidance in Table F. 1(a), in the growth should be created and the executable code should be copied
phase of the fire, Q is taken specifically as follows: into that directory. The code operates on an IBM PC ot­
compatible computer containing a math coprocessor. It is writ­
ten in Fortran 77 and needs a minimum of 300 kilobytes of
[C.3a]
mem01-y.
Q = 1000 (- -1
130 sec
) Bnt/sec
2
To execute LAVENT, change to the proper directory or
insert a floppy disk containing a copy of the executable code
and enter LAVENT <ret>. In this case, <ret> refet-s to the

( -- ) \w
[C.3b]
1
Q = 1055 Draft curtain
130sec
The fire grows according to the preceding estimate until t�e
combustibles are fully involved. It is then assumed that Q
• • • • • • •

� ?' �·
levels off to a relatively constant value. Following the guidance
of Table 4.1 of reference [ 1 ] and Table A.8.2.6, it is estimated
L1
that, at the fully developed stage of the fire, the total energy • •
release rate for the 5 ft (1.5 m) high stack of wood pallets will L2 4
be 330 Btu/sec · ft2 (3743 kW·m2 ) , or 33,000 Btu/sec (34,800
kW) for the entire 100 ft2 (9.3 m2) array. Equations C.3a and
C.3b lead to the result that the fully developed stage of the fire
•
. . . ""'Fire
.
• •

will be initiated at t1d = 747 seconds. L

• • • •

�' :
A plot of the fire growth according to the preceding descrip­ Vent
;ink:r
tion is shown in Figure C.3(b). In the acntal calculation, the
• • •

�
fire's instantaneous energy release rate is estimated by intet-po­
lating linearly bet\veen a series of N input data points at times
t., n = 1 to N, on the fire-growtjl CLJrve. These points are • • •
defined by user-specified values of L t, ,Q ( t, )] . For times larger
that1 tN • the fire's energy release rate is assumed to stay constant
at Q lt.v ) . The calculation fire-growth curve involves six input • • • • • • •
data points (i.e., N = 6). These points are plotted in Figure
C.3(b). 01 = 12 ft L1 = 6 ft: 2 sprinklers
02 = 21 ft L2 = 21.2 ft: 2 vents
The position of the fire's center is identified in Figure 03 =42ft L3 = 44.3 ft: 2 vents
C.3(a). In terms of this plan view, the fire is assumed to be loca­ � = 13.4 ft: 4 sprinklers
ted at the midpoint of a 12 ft (3.7 m) line bet\veen t\'i'o sprin­ For Sl units, 1 ft = 0.305 m
kler links, at a distance of 21.2 ft (6.5 m) fi-om each of the 1:\vo
closest equidistant vents r a total at-e a of 96 ft2 (8.9 m2 ) ] and at FIGURE C.3(a) Vent and Sprinkler Spacing and Fire
a distance of 44.3 ft (13.5 m) from the remaining t:\'1'0 equidis­ Location for the Default Sinmlation.
tant vents fa total area of 96 t't2 (8.9 m2) l . Of the sprinklers and

2021 Edition
 ANNEX C 204-43

ENTER or RETURN key. The first prompt provides an option whether the A or B drive is being used. It is recommended that
for English 01- meu-ic units: all data files use a common extender such as ".dat" to facilitate
identification of these files.
1 FOR ENGLISH UNITS
A first-time user should select Option 4, RUN THE
2 FOR METRIC UNITS DEFAULT CASE, by entering 4 <ret>. This selection will ensure
The program has a lmit conversion flmction and transforms that the code has been transferred intact. The default-case
files that are in one set of units to another set. The code output s i provided in Figure C.4 and is discussed in
executes in SI units; therefore, conversion is done only on Section C.8. As a point of information, the times needed to
input and output in order to avoid rounding errors. carry out the default simulation on IBM PC-compatible 486/33
MHZ and Pentium/90 MHZ computers were 40 seconds and
For the purposes of getting started, choose Option 1 , 8 seconds, respectively.
ENGLISH UNITS. Enter 1 <ret>. The following menu will be
displayed on the screen: Now restart the code and, at this point, choose Option 3,
MODIFY THE DEFAULT CASE, to review and modify the
1 READ AND RUN A DATA FILE default input data. Enter 3 <t·et>.
2 READ AND MODIFY A DATA FILE C.5 The Base Menu.
3 MODIFY THE DEFAULT CASE TO CREATE A NEW FILE C.5.1 Modifying the Default Case - General. vVhen Option
4 RUN THE DEFAULT CASE 3, MODIFY THE DEFAULT CASE, is chosen, the following
menu is displayed:
If Option 1 or 2 is chosen, the program will ask for the name
of the data file to be used. If the chosen file resides on the hard 1 ROOM PROPERTIES
disk, this question should be answered by typing the path of the 2 PHYSICAL PROPERTIES
file name, for example, C:\�ubdirectory\filename. If the file is
on a floppy disk, type A:filename or B:filename, depending on 3 OUTPUT PARAMETERS
4 FUSIBLE LINK PROPERTIES

40(1 cil) 5 FIRE PROPERTIES

6 SOLVER PARAMETERS
0 NO CHANGES
30(1 03)
This menu will be referred to as the base menu.
g
(/) Entering the appropriate option number of the base menu
:,
§. 20(1 03)
and then <ret> will always transfer the user to the indicated
•0 item on the menu. Entet-ing a zero will u-ansfer the user to the
file status portion of the input section discussed in Section C.6.
The next subsections discuss data entry under Options 1
1 0(1 cil) through 6 of the base menu.
Now choose Option 1, ROOM PROPEliTIES, of the base
menu to review and modify the default room-property input
data. Enter 1 <ret>.
200 400 600 800
Time (sec)
For Sl units, 1 Btu/sec 1.055 kW
=

FIGURE C.3(b) Energy Release Rate vs. Time for the Fire
of the Default Simulation.

2021 Edition
204-44 SMOKE AND HEAT VENTLNG

CEILING HEIGHT 3 0 . 0 FT
ROOM LENGTH = 8 4 . 0 FT
ROOM WIDTH = 8 4 . 0 FT
CURTAIN LENGTH 3 3 6 . 0 FT
CURTAIN I'IEIGHT 1 5 . 0 FT
MATERIAL = INSULATED DECK (SOLID POLYSTYRENE)
CEILING CONDUCTIVITY .240E-04 BTU/FT F S
CEILING DENSITY = .655E+02 LB/FT3
CEILING HEAT CAPACITY . 2 7 7E+00 BTU/LB F
CEILING THICKNESS . 5 00E+OO FT
FIRE HEIGHT = 2 . 5 FT
FIRE POWER/AREA 0 . 3 3 00E+03 BTU/S FT2

LINK NO 1 RADIUS = 6 . 0 FT DIST CEILING = 1 . 00 FT

RTI= 4 0 0 . 0 0 SQRT FUSION TEMPERATURE FOR LINK = 165.00 K
LINK NO 2 RADIUS = 2 1 . 2 FT DIST CEILING = 0 . 3 0 FT
RTI= 5 0 . 0 0 SQRT FUSION TEMPERATURE FOR LINK = 165.00 K
LINK NO 3 RADIUS = 4 4 . 3 FT DIST CEILING = 0 . 3 0 FT
RTI= 5 0 . 0 0 SQRT FUSION TEMPERATURE FOR LINK = 165.00 K
VENT VENT AREA 9 6 . 0 FT2 LINK CONTROLLING VENT 2
VENT 2 VENT AREA 9 6 . 0 FT2 LINK CONTROLLING VENT 3

TIME ( S ) = 0 . 0 0 0 LYR TEMP ( F ) = 8 0 . 0 LYR BT ( F T ) = 3 0 . 0 0 LYR MASS (LB)= O . O OOE+OO

FIRE OUTPUT (BTU/S)= O . O O O OE+OO VENT AREA (FT2)= 0.00
LINK LINK TEMP ( F ) = 8 0 . 0 0 JET VELOCITY (FT/S)= 0 . 0 0 0 JET TEMP ( F ) 80.0
LINK LINK TEMP ( F ) = 8 0 . 0 0 JET VELOCITY (FT/S)= 0 . 0 0 0 JET TEMP ( F ) 80.0
LINK 3 LINK TEMP ( F ) = 8 0 . 0 0 JET VELOCITY (FT/S)= 0 . 0 0 0 JET TEMP ( F ) 80.0
R (FT)= 0 . 0 0 TSL ( F ) = 8 0 . 0 Q B (BTU/FT2 S ) = O . O O OE+OO Q T (BTU/FT2 S ) = O . O OOE+OO
R (FT)= 12 • 4 1 TSL ( F ) = 8 0 . 0 QB (BTU/FT2 S ) = O . O OOE+OO QT (BTU/FT2 S)= O . O OOE+OO
R (FT)= 2 4 . 8 2 TSL ( F ) = 8 0 . 0 QB (BTU/FT2 S ) = O . O OOE+OO QT (BTU/FT2 S)= O . O OOE+OO
R (FT)= 3 7 . 2 3 TSL ( F ) = 8 0 . 0 QB (BTU/FT2 S ) = O . O OOE+OO QT (BTU/FT2 S)= O . O OOE+OO
R (FT)= 4 9 . 6 4 TSL ( F ) = 8 0 . 0 QB (BTU/FT2 S ) = O . OOOE+OO QT (BTU/FT2 S)= O . O OOE+OO
R (FT)= 6 2 . 0 5 TSL ( F ) = 8 0 . 0 QB (BTU/FT2 S ) = O . OOOE+OO QT (BTU/FT2 S)= O . O OOE+OO

TIME ( S ) = 3 0 . 0 0 0 LYR TEMP ( F ) = 8 9 . 6 LYR B T ( F T ) = 2 8 . 9 0 LYR MASS (LB)= 0 . 562E+03

FIRE OUTPUT (BTU/S)= 0 . 1 7 76E+03 VENT AREA (FT2)= 0.00
LINK LINK TEMP ( F ) = 8 0 . 7 8 JET VELOCITY (FT/S)= 1 . 8 6 6 JET TEMP ( F ) 94.9
LINK 2 LINK TEMP ( F ) = 8 5 . 3 7 JET VELOCITY (FT/S)= 2 . 0 7 7 JET TEMP ( F ) 95.3
LINK 3 LINK TEMP ( F ) = 8 1 . 8 3 JET VELOCITY (FT/S)= 0 . 8 7 3 JET TEMP ( F ) 87.4
R (FT)= 0 . 0 0 TSL ( F ) = 84 . 5 Q B (BTU/FT2 S ) = 0 . 3 12E-01 Q T ( BTU/FT2 S ) = 0 . 847E-18
R (FT)= 1 2 . 4 1 TSL ( F ) = 8 1 . 7 Q B (BTU/FT2 S ) = 0 . 122E-01 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 8 0 . 8 QB (BTU/FT2 S ) = 0 . 5 7 0E-02 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 3 7 . 2 3 TSL ( F ) = 8 0 . 4 QB (BTU/FT2 S ) = 0 . 325E-02 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 4 9 . 6 4 TSL ( F ) = 8 0 . 3 QB (BTU/FT2 S ) = 0 . 2 12E-02 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 8 0 . 2 QB (BTU/FT2 S ) = 0 . 152E-02 QT (BTU/FT2 S)= 0 . 847E-18

TIME ( S ) = 6 0 . 0 0 0 LYR TEMP ( F ) = 9 6 . 5 LYR H T ( F T ) = 2 7 . 34 LYR MASS (LB)= 0 . 134E+04

FIRE OUTPUT (BTU/S)= 0 . 3552E+03 VENT AREA (FT2)= 0.00
LINK 1 LINK TEMP ( F ) = 8 2 . 8 0 JET VELOCITY (FT/S)= 2 . 3 9 5 JET TEMP (F) = 105.0
LINK LINK TEMP ( F ) = 9 5 . 1 3 JET VELOCITY (FT/S)= 2 . 6 5 7 JET TEMP ( F ) 105.8
LINK LINK TEMP ( F ) = 8 5 . 7 6 JET VELOCITY (FT/S)= 1 . 1 1 7 JET TEMP ( F ) 92.9
R (FT)= 0 . 0 0 TSL ( F ) = 92 . 7 Q B (BTU/FT2 S ) = 0 . 5 17E-01 Q T ( BTU/FT2 S ) = 0 . 847E-18
R (FT)= 1 2 . 4 1 TSL ( F ) = 8 5 . 2 QB (BTU/FT2 S ) = 0 . 223E-01 QT ( BTU/FT2 S)= 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 82 . 5 QB (BTU/FT2 S ) = 0 . 107E-01 QT ( BTU/FT2 S)= 0 . 847E-18
R (FT)= 3 7 . 2 3 TSL ( F ) = 8 1 . 4 QB (BTU/FT2 S ) = 0 . 619E-02 QT ( BTU/FT2 S)= 0 . 847E-18
R (FT)= 4 9 . 6 4 TSL ( F ) = 8 0 . 9 QB (BTU/FT2 S ) = 0 . 405E-02 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 8 0 . 6 QB (BTU/FT2 S ) = 0 . 292E-02 QT (BTU/FT2 S)= 0 . 847E-18

TIME ( S ) = 9 0 . 0 0 0 LYR TEMP ( F ) = 1 0 3 . 2 LYR B T ( F T ) = 2 5 . 6 5 LYR MASS (LB)= 0 . 2 16E+04

FIRE OUTPUT (BTU/S)= 0 . 5328E+03 VENT AREA (FT2)= 0.00
LINK LINK TEMP ( F ) = 8 5 . 9 0 JET VELOCITY (FT/S)= 2 . 8 0 9 JET TEMP ( F ) 114.5
LINK LINK TEMP ( F ) = 1 0 5 . 7 4 JET VELOCITY (FT/S)= 3 . 1 0 4 JET TEMP ( F ) 115.8
LINK LINK TEMP ( F ) = 9 0 . 6 6 JET VELOCITY (FT/S)= 1 . 3 0 5 JET TEMP ( F ) 98.2

FIGURE C.4 Printout of the Default-Case Output.

2021 Edition
 ANNEX C 204-45

R (FT)= 0 . 0 0 TSL ( F ) = 1 0 2 . 4 QB (BTU/FT2 S ) = 0 . 6 87E-01 QT (BTU/FT2 S ) = 0 . 847E-18

R (FT)= 1 2 . 4 1 TSL ( F ) = 8 9 . 7 QB (BTU/FT2 S ) = 0 . 3 17E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 84 . 7 QB (BTU/FT2 S ) = 0 . 156E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 3 7 . 2 3 TSL ( F ) = 82 . 7 QB (BTU/FT2 S ) = 0 . 9 08E-02 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 4 9 . 6 4 TSL ( F ) = 8 1 . 8 QB (BTU/FT2 S ) = 0 . 5 9 8E-02 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 8 1 . 1 QB (BTU/FT2 S ) = 0 . 9 87E-03 QT (BTU/FT2 S)= 0 . 847E-18

TIME ( S ) = 1 2 0 . 0 0 0 LYR TEMP (F)= 1 1 1 . 5 LYR BT ( F T ) = 2 3 . 85 LYR MASS (LB)= 0 . 3 0 1E+04

FIRE OUTPUT (BTU/S)= 0 . 94 7 0E+03 VENT AREA (FT2)= 0.00
LINK LINK TEMP ( F ) = 9 0 . 3 0 JET VELOCITY (FT/S)= 3 . 614 JET TEMP ( F ) 129.3
LINK LINK TEMP ( F ) = 1 1 8 . 4 3 JET VELOCITY (FT/S)= 3 . 9 66 JET TEMP ( F ) 132.1
LINK LINK TEMP ( F ) = 9 6 . 6 6 JET VELOCITY (FT/S)= 1 . 6 6 7 JET TEMP (F) 106.2
R (FT)= 0 • 0 0 TSL ( F ) = 115 . 6 QB (BTU/FT2 S ) = 0 . 1 13E+OO Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 12 • 4 1 TSL ( F ) = 96.2 QB (BTU/FT2 S)= 0 . 543E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 8 7 . 9 QB (BTU/FT2 S ) = 0 . 266E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 3 7 . 2 3 TSL ( F ) = 84 . 6 QB (BTU/FT2 S ) = 0 . 1 54E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 4 9 . 6 4 TSL ( F ) = 8 3 . 0 QB (BTU/FT2 S ) = 0 . 1 01E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 82 . 0 QB (BTU/FT2 S ) = 0 . 7 2 8E-02 QT (BTU/FT2 S)= 0 . 847E-18

TIME ( S ) = 1 5 0 . 0 0 0 LYR TEMP (F)= 1 2 4 . 4 LYR BT ( F T ) = 2 1 . 8 5 LYR MASS (LB)= 0 . 3 90E+04

FIRE OUTPUT (BTU/S)= 0 . 1479E+04 VENT AREA (FT2)= 0.00
LINK 1 LINK TEMP ( F ) = 9 7 . 1 6 JET VELOCITY (FT/S)= 4 . 3 6 4 JET TEMP ( F ) 149.2
LINK 2 LINK TEMP ( F ) = 1 3 7 . 3 7 JET VELOCITY (FT/S)= 4 . 75 4 JET TEMP ( F ) 153.4
LINK 3 LINK TEMP ( F ) = 1 0 5 . 4 9 JET VELOCITY (FT/S)= 1 . 9 9 8 JET TEMP ( F ) 117.4
R (FT)= 0 . 0 0 TSL ( F ) = 1 3 6 . 5 Q B (BTU/FT2 S ) = 0 . 1 58E+OO Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 1 2 . 4 1 TSL ( F ) = 1 0 7 . 0 QB (BTU/FT2 S ) = 0 . 8 10E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 9 3 . 3 QB (BTU/FT2 S ) = 0 . 4 05E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 3 7 . 2 3 TSL ( F ) = 8 7 . 7 QB (BTU/FT2 S ) = 0 . 236E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 4 9 . 6 4 TSL ( F ) = 8 5 . 1 QB (BTU/FT2 S ) = 0 . 1 55E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 83 . 5 QB (BTU/FT2 S ) = 0 . 1 12E-01 QT (BTU/FT2 S)= 0 . 847E-18

TIME ( S ) = 1 8 0 . 0 0 0 LYR TEMP ( F ) = 1 4 0 . 2 LYR H T ( F T ) = 1 9 . 7 7 LYR MASS (LB)= 0 . 4 77E+04

FIRE OUTPUT (BTU/S)= 0 . 2 0 12E+04 VENT AREA (FT2)= 0.00
LINK 1 LINK TEMP ( F ) = 1 0 6 . 6 6 JET VELOCITY (FT/S)= 5 . 0 0 8 JET TEMP ( F ) 171.4
LINK 2 LINK TEMP ( F ) = 1 5 9 . 6 8 JET VELOCITY (FT/S)= 5 . 4 1 4 JET TEMP ( F ) 176.5
LINK 3 LINK TEMP ( F ) = 1 1 6 . 6 9 JET VELOCITY (FT/S)= 2 . 2 7 5 JET TEMP ( F ) 130.2
R (FT)= 0 . 0 0 TSL ( F ) = 1 6 0 . 3 Q B (BTU/FT2 S ) = 0 . 195E+OO Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 1 2 . 4 1 TSL ( F ) = 1 2 0 . 4 Q B (BTU/FT2 S ) = 0 . 1 06E+00 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 1 0 0 . 2 Q B (BTU/FT2 S ) = 0 . 545E-01 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 3 7 . 2 3 TSL ( F ) = 9 1 . 8 Q B (BTU/FT2 S ) = 0 . 322E-01 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 4 9 . 6 4 TSL ( F ) = 8 7 . 8 QB (BTU/FT2 S ) = 0 . 2 13E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 8 5 . 3 QB (BTU/FT2 S ) = 0 . 332E-02 QT (BTU/FT2 S)= 0 . 847E-18

TIME ( S ) = 2 1 0 . 0 0 0 LYR TEMP (F)= 1 5 8 . 7 LYR BT ( F T ) = 1 9 . 5 9 LYR MASS (LB)= 0 . 47 1E+04

FIRE OUTPUT (BTU/S)= 0 . 2722E+04 VENT AREA (FT2)= 96.00
LINK LINK TEMP ( F ) = 1 1 8 . 8 5 JET VELOCITY (FT/S)= 5 . 6 0 5 JET TEMP ( F ) 196.8
LINK LINK TEMP ( F ) = 1 8 4 . 0 3 JET VELOCITY (FT/S)= 6 . 02 1 JET TEMP ( F ) 202.7
LINK LINK TEMP ( F ) = 1 2 9 . 7 1 JET VELOCITY (FT/S)= 2 . 5 3 0 JET TEMP ( F ) 144.9
TIME LINK 2 OPENS EQUALS 1 8 6 . 74 7 8 (S)
R (FT)= 0 . 0 0 TSL ( F ) = 1 8 5 . 7 Q B (BTU/FT2 S ) = 0 . 239E+00 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 1 2 . 4 1 TSL ( F ) = 135 . 8 Q B (BTU/FT2 S ) = 0 . 1 37E+00 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 1 0 8 . 5 QB (BTU/FT2 S ) = 0 . 7 18E-01 QT (BTU/FT2 S)= 0 . 847E-18

R (FT)= 3 7 . 2 3 TSL ( F ) = 9 6 . 8 QB (BTU/FT2 S ) = 0 . 427E-01 QT (BTU/FT2 S)= 0 . 847E-18

R (FT)= 4 9 . 6 4 TSL ( F ) = 9 1 . 1 QB (BTU/FT2 S ) = 0 . 2 85E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 8 7 . 2 QB (BTU/FT2 S ) = 0 . 2 10E-01 QT (BTU/FT2 S)= 0 . 847E-18

TIME ( S ) = 2 4 0 . 0 0 0 LYR TEMP ( F ) = 1 8 4 . 9 LYR BT (FT)= 1 9 . 7 7 LYR MASS (LB)= 0 . 444E+04

FIRE OUTPUT (BTU/S)= 0 . 37 87E+04 VENT AREA (FT2)= 96.00
LINK LINK TEMP ( F ) = 1 3 4 . 8 9 JET VELOCITY (FT/S)= 6 . 3 2 7 JET TEMP ( F ) 231.8
LINK LINK TEMP ( F ) = 2 1 5 . 6 9 JET VELOCITY (FT/S)= 6 . 74 1 JET TEMP ( F ) 238.2
LINK LINK TEMP ( F ) = 146.44 JET VELOCITY (FT/S)= 2 . 832 JET TEMP ( F ) 165.1
TIME LINK OPENS EQUALS 1 8 6 . 74 7 8 (S)

FIGURE C.4 Continued

2021 Edition
204-46 SMOKE AND HEAT VENTLNG

R (FT)= 0 . 0 0 TSL ( F ) = 2 1 8 . 6 Q B (BTU/FT2 S ) = 0 . 299E+00 Q T (BTU/FT2 S ) = 0 . 847E-18

R (FT)= 1 2 . 4 1 TSL ( F ) = 1 56 . 6 QB (BTU/FT2 S ) = 0 . 1 80E+OO QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 1 1 9 . 9 QB (BTU/FT2 S ) = 0 . 9 7 1E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 3 7 . 2 3 TSL ( F ) = 1 0 3 . 7 QB (BTU/FT2 S ) = 0 . 5 82E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 4 9 . 6 4 TSL ( F ) = 9 5 . 7 QB (BTU/FT2 S ) = 0 . 389E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 9 0 . 3 QB (BTU/FT2 S ) = 0 . 2 88E-01 QT (BTU/FT2 S)= 0 . 847E-18

TIME ( S ) = 2 7 0 . 0 0 0 LYR TEMP (F)= 2 1 7 . 5 LYR HT (FT)= 2 0 . 1 7 LYR MASS (LB)= 0 . 407E+04
FIRE OUTPUT (BTU/S)= 0 . 4 8 52E+04 VENT AREA (FT2)= 192.00
LINK 1 LINK TEMP ( F ) = 1 5 5 . 4 9 JET VELOCITY (FT/S)= 6 . 854 JET TEMP ( F ) 271.3
LINK 2 LINK TEMP ( F ) = 2 5 3 . 1 9 JET VELOCITY (FT/S)= 7 . 2 4 4 JET TEMP ( F ) 277.0
LINK 3 LINK TEMP ( F ) = 1 6 7 . 2 4 JET VELOCITY (FT/S)= 3 . 04 3 JET TEMP ( F ) 188.5
TIME LINK OPENS EQUALS 1 8 6 . 74 7 8 (S)
TIME LINK OPENS EQUALS 266.9820 (S)
R (FT)= 0 . 0 0 TSL ( F ) = 2 5 4 . 4 Q B (BTU/FT2 S ) = 0 . 339E+00 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 1 2 . 4 1 TSL ( F ) = 1 8 1 . 1 Q B (BTU/FT2 S ) = 0 . 2 17E+00 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 1 33 . 9 Q B (BTU/FT2 S ) = 0 . 121E+OO Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 3 7 . 2 3 TSL ( F ) = 1 12 . 2 QB (BTU/FT2 S ) = 0 . 7 3 5E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 4 9 . 6 4 TSL ( F ) = 1 0 1 . 5 QB (BTU/FT2 S ) = 0 . 494E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 9 3 . 7 QB (BTU/FT2 S ) = 0 . 371E-01 QT (BTU/FT2 S)= 0 . 847E-18

TIME ( S ) = 3 0 0 . 0 0 0 LYR TEMP (F)= 2 5 3 . 4 LYR RT (FT)= 2 2 . 8 4 LYR MASS (LB)= 0 . 2 81E+04
FIRE OUTPUT (BTU/S)= 0 . 59 1 8E+04 VENT AREA (FT2)= 192.00
LINK LINK TEMP ( F ) = 1 7 9 . 5 9 JET VELOCITY (FT/S)= 6 . 9 0 1 JET TEMP ( F ) 308.7
LINK 2 LINK TEMP ( F ) = 2 8 9 . 6 7 JET VELOCITY (FT/S)= 7 . 19 5 JET TEMP ( F ) 311.3
LINK 3 LINK TEMP ( F ) = 1 8 9 . 7 7 JET VELOCITY (FT/S)= 3 . 02 3 JET TEMP ( F ) 211.4
TIME LINK OPENS EQUALS 282.8710 (S)
TIME LINK OPENS EQUALS 1 8 6 . 74 7 8 (S)
TIME LINK OPENS EQUALS 266.9820 (S)
R (FT)= 0 . 0 0 TSL ( F ) = 2 8 7 . 1 Q B (BTU/FT2 S ) = 0 . 352E+OO Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 12 • 4 1 TSL ( F ) = 2 0 5 . 5 Q B (BTU/FT2 S ) = 0 . 2 3 8E+OO Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 148 . 7 QB (BTU/FT2 S ) = 0 . 1 38E+00 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 3 7 . 2 3 TSL ( F ) = 1 2 1 . 5 QB (BTU/FT2 S ) = 0 . 8 51E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 4 9 . 6 4 TSL ( F ) = 1 0 7 . 8 QB (BTU/FT2 S ) = 0 . 5 74E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 9 8 . 8 QB (BTU/FT2 S ) = 0 . 428E-01 QT (BTU/FT2 S)= 0 . 847E-18

TIME ( S ) = 3 3 0 . 0 0 0 LYR TEMP ( F ) = 2 8 4 . 4 LYR B T ( F T ) = 2 4 . 2 5 LYR MASS ( L B ) = 0 . 2 16E+04

FIRE OUTPUT (BTU/S)= 0 . 6 9 8 3E+04 VENT AREA (FT2)= 192.00
LINK 1 LINK TEMP ( F ) = 2 0 6 . 0 5 JET VELOCITY (FT/S)= 7 . 1 0 9 JET TEMP ( F ) 342.3
LINK 2 LINK TEMP ( F ) = 3 2 2 . 5 8 JET VELOCITY (FT/S)= 7 . 2 2 7 JET TEMP ( F ) 341.6
LINK 3 LINK TEMP ( F ) = 2 1 1 . 7 7 JET VELOCITY (FT/S)= 3 . 0 3 6 JET TEMP ( F ) 231.8
TIME LINK OPENS EQUALS 282.8710 (S)
TIME LINK OPENS EQUALS 1 8 6 . 74 7 8 (S)
TIME LINK OPENS EQUALS 266.9820 (S)
R (FT)= 0 . 0 0 TSL ( F ) = 3 1 6 . 3 Q B (BTU/FT2 S ) = 0 . 366E+OO Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 1 2 . 4 1 TSL ( F ) = 229 . 1 Q B (BTU/FT2 S ) = 0 . 2 57E+00 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 1 63 . 7 QB (BTU/FT2 S ) = 0 . 1 5 3E+OO QT (BTU/FT2 S)= 0 . 847E-18

R (FT)= 3 7 . 2 3 TSL ( F ) = 1 3 0 . 9 Q B (BTU/FT2 S ) = 0 . 952E-01 Q T (BTU/FT2 S ) = 0 . 847E-18

R (FT)= 4 9 . 6 4 TSL ( F ) = 1 1 4 . 2 QB (BTU/FT2 S ) = 0 . 644E-01 QT (BTU/FT2 S)= 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 1 0 3 . 0 QB (BTU/FT2 S ) = 0 . 4 81E-01 QT (BTU/FT2 S)= 0 . 847E-18

TIME ( S ) = 3 6 0 . 0 0 0 LYR TEMP ( F ) = 3 0 7 . 3 LYR BT (FT)= 2 4 . 7 7 LYR MASS (LB)= 0 . 19 1E+04

FIRE OUTPUT (BTU/S)= 0 . 8 0 4 8E+04 VENT AREA (FT2)= 192.00
LINK LINK TEMP ( F ) = 2 3 3 . 8 0 JET VELOCITY (FT/S)= 7 . 5 5 9 JET TEMP ( F ) 370.4
LINK 2 LINK TEMP ( F ) = 3 5 1 . 1 1 JET VELOCITY (FT/S)= 7 . 4 6 1 JET TEMP ( F ) 367.4
LINK 3 LINK TEMP ( F ) = 2 3 1 . 5 1 JET VELOCITY (FT/S)= 3 . 134 JET TEMP ( F ) 248.9
TIME LINK OPENS EQUALS 282.8710 (S)
TIME LINK OPENS EQUALS 1 8 6 . 74 7 8 (S)

TIME LINK OPENS EQUALS 266.9820 (S)

R (FT)= 0 . 0 0 TSL ( F ) = 3 4 4 . 3 Q B (BTU/FT2 S ) = 0 . 3 80E+00 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 1 2 . 4 1 TSL ( F ) = 2 52 . 3 QB (BTU/FT2 S ) = 0 . 275E+OO QT (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 1 7 8 . 8 QB (BTU/FT2 S ) = 0 . 1 67E+OO QT (BTU/FT2 S)= 0 . 847E-18

FIGURE C.4 Continued

2021 Edition
 ANNEX C 204-47

R (FT)= 3 7 . 2 3 TSL ( F ) = 1 4 0 . 5 Q B (BTU/FT2 S ) = 0 . 1 05E+OO Q T (BTU/FT2 S ) = 0 . 847E-18

R (FT)= 4 9 . 6 4 TSL ( F ) = 120 . 8 QB (BTU/FT2 S ) = 0 . 7 09E-01 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 1 0 7 . 5 QB (BTU/FT2 S ) = 0 . 5 30E-01 Q T (BTU/FT2 S ) = 0 . 847E-18

TIME ( S ) = 3 9 0 . 0 0 0 LYR TEMP (F)= 3 2 7 . 0 LYR BT (FT)= 2 4 . 81 LYR MASS (LB)= 0 . 1 8 5E+04
FIRE OUTPUT (BTU/S)= 0 . 9 1 13E+04 VENT AREA (FT2)= 192.00
LINK 1 LINK TEMP ( F ) = 2 6 2 . 3 2 JET VELOCITY (FT/S)= 8 . 1 6 8 JET TEMP ( F ) 397.0
LINK = 2 LINK TEMP ( F ) = 3 7 6 . 9 2 JET VELOCITY (FT/S)= 7 . 8 1 1 JET TEMP ( F ) 392.0
LINK = 3 LINK TEMP ( F ) = 2 4 9 . 1 9 JET VELOCITY (FT/S)= 3 . 2 8 1 JET TEMP ( F ) 264.9
TIME LINK 1 OPENS EQUALS 282.8710 (S)
TIME LINK 2 OPENS EQUALS 1 8 6 . 74 7 8 (S)
TIME LINK 3 OPENS EQUALS 266.9820 (S)
R (FT)= 0 . 0 0 TSL ( F ) = 3 72 . 0 Q B (BTU/FT2 S ) = 0 . 3 98E+OO Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 1 2 . 4 1 TSL ( F ) = 275 . 6 Q B (BTU/FT2 S ) = 0 . 294E+OO Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 1 94 . 1 Q B (BTU/FT2 S ) = 0 . 1 81E+00 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 3 7 . 2 3 TSL ( F ) = 1 5 0 . 3 Q B (BTU/FT2 S ) = 0 . 1 14E+00 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 4 9 . 6 4 TSL ( F ) = 1 2 7 . 5 QB (BTU/FT2 S ) = 0 . 7 73E-01 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 1 1 3 . 2 QB (BTU/FT2 S ) = 0 . 5 74E-01 Q T (BTU/FT2 S ) = 0 . 847E-18

TIME ( S ) = 4 0 0 . 0 0 0 LYR TEMP (F)= 3 3 3 . 5 LYR BT (FT)= 2 4 . 7 7 LYR MASS (LB)= 0 . 1 8 5E+04
FIRE OUTPUT (BTU/S)= 0 . 9468E+04 VENT AREA (FT2)= 192.00
LINK 1 LINK TEMP ( F ) = 2 7 1 . 9 8 JET VELOCITY (FT/S)= 8 . 3 87 JET TEMP ( F ) 406.0
LINK = 2 LINK TEMP ( F ) = 3 8 5 . 3 2 JET VELOCITY (FT/S)= 7 . 936 JET TEMP ( F ) 400.2
LINK = 3 LINK TEMP ( F ) = 2 5 4 . 8 5 JET VELOCITY (FT/S)= 3 . 33 3 JET TEMP ( F ) 270.2
TIME LINK 1 OPENS EQUALS 282.8710 (S)
TIME LINK OPENS EQUALS 1 8 6 . 74 7 8 (S)
TIME LINK OPENS EQUALS 266.9820 (S)
R (FT)= 0 . 0 0 TSL ( F ) = 3 8 1 . 3 Q B (BTU/FT2 S ) = 0 . 4 03E+00 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 1 2 . 4 1 TSL ( F ) = 2 8 3 . 5 Q B (BTU/FT2 S ) = 0 . 3 00E+00 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 2 4 . 8 2 TSL ( F ) = 1 9 9 . 2 Q B (BTU/FT2 S ) = 0 . 1 86E+OO Q T (BTU/FT2 S ) = 0 . 847£-18
R (FT)= 3 7 . 2 3 TSL ( F ) = 1 53 . 6 QB (BTU/FT2 S ) = 0 . 1 17E+00 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 4 9 . 6 4 TSL ( F ) = 129 . 7 QB (BTU/FT2 S ) = 0 . 794E-01 Q T (BTU/FT2 S ) = 0 . 847E-18
R (FT)= 6 2 . 0 5 TSL ( F ) = 1 1 5 . 0 Q B (BTU/FT2 S ) = 0 . 5 89£-01 Q T (BTU/FT2 S ) = 0 . 847E-18

FIGURE C.4 Continued

C.5.2 Room Properties. '.l\lhen Option 1 , ROOM PROPER­ WARNING: The t1ser is warned that it is critical to end each ent-ry
TIES, of the base menu is chosen, the following room proper­ numb er with a decimal point when a noninteger number s i indicated
ties menu is displayed: (i.e., when the sn-een display shows a decimal point jm· that entry). 17te
user is warned jurtlte1· that the code will attempt to run with any speci­
fied input file and that it will not distinguish between Tealistic and
30.00000 CEILfNG HEIGHT (FT) unrealistic input values.
2 84.00000 ROOM LENGTH (FT)
3 84.00000 ROOM WIDTH (FT) Option 6, HEIGHT TO BOTTOM OF CURTAIN, of the
4 2 NUMBER OF VENTS, ETC. room pt·operties menu is used to define the height above the
5 336.00000 CURTAIN LENGTH (FT) floor of the bottom of the curtain. As can be seen, in the
6 15.00000 HEIGHT TO BOTTOM OF default data, this is 15 ft. Where this height is chosen to be
identical to the ceiling height, the user should always define
CURTAIN (FT)
the very special idealized simulation associated with an exten­
0 TO CHANGE NOTHING
sive, unconfined ceiling fire scenario (i.e., by whatever means,
it is assumed that the flow of the ceiling jet is extracted from
All input values are expressed in either S.I. or U.S. custom­ the compartment at the extremities of the ceiling). Under such
ary units, and the units are prompted on the input menus. a simulation, an upper layer never develops in the compart­
Note that the default number of vents is 2, not 4, because ment. The lower-ceiling surface and fusible links are
the symmetry of the default scenario, as indicated in Figure submerged in and respond to an unconfined ceiling jet envi­
C.3(a), leads to "ganged" operation of each of avo pairs of the ronment, which is unaffected by layer growth. This idealized
four vents involved. fire scenario, involving the unconfined ceiling, is used, for
example, in reference [ 1 ] to simulate ceiling response and in
To change an input value in the preceding room properties references f2) and f3] to simulate sprinkler response.
menu - for example, to change the ceiling height fi·om 30 ft
to 20 ft - the user would enter 1 <ret> and 20. <ret>. The The choice of some options on a menu, such as Option 4,
screen would show revisions using the new value of20 ft for the NUMBER OF VENTS, ETC., of the room properties menu,
ceiling height. This value or other values on this screen can be leads to a subsequent display/requirement of additional associ­
changed by repeating the process. ated input data. Menu options that necessitate multiple enu·ies
are indicated by the use of "ETC." In the case of Option 4,

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204-48 SMOKE AND HEAT VENTLNG

NUMBER OF VENTS, ETC., three values are involved for each ENTER 0 TO RETURN TO THE MENU
vent or group of vents actuated by a fusible link. As indicated
under Option 4, NUMBER OF VENTS, ETC., the default data To add or reimplement vent number 2, actuated by link
describe a scenario with two vents or groups of vents. number 3 and of area 96 ft2 , enter 2 <ret>, 3 <ret>, 96. <ret>.
Now return to the original default scenario by bringing the
Now choose Option 4, NUMBER OF VENTS, ETC., to review area of vent number 1 back to its original 96 ft2 value; enter
and modify the default input data associated with these tw·o l<ret>, 2 <ret>, and 96. <ret>.
vents or groups of vents. Enter 4 <ret>. The following is
displayed on the screen: The user can now continue to modifY or add additional ceil­
ing vents or rentrn to the room properties menu by entering 0
VENT NO. = 1 FUSIBLE LINK = 2 VENT AREA = 96.00000 <ret>. If the user tries to associate a vent with a link not yet
IT2 entered in the program, the code will warn the user, give the
maximum number of links available in the present data set,
VENT NO. = 2 FUSIBLE LINK = 3 VENT AREA = 96.00000 and request a new link value. If the user deletes a link that is
IT2 a�signed to a vent, the code will assign the link with the next
ENTER 6 TO REMOVE A VENT smallest number to that vent. The best med10d for assigning
vents to links is to first use Option 4, FUSIBLE LINK PROPER­
ENTER VENT NO., LINK NO., AND VENT AREA (FT2) TO TIES, of the base menu (to be discussed in C.5.5) to assign the
ADD OR MODIFY A VENT link parameters and then to use Option 1, ROOM PROPER­
MAXIMUM NO. OF VENTS IS 5 TIES, followed by the option NUMBER OF VENTS, ETC. to
assign vent properties.
ENTER 0 TO RETURN TO THE MENU
Now remrn to the mom properties menu by entering 0
This display indicates that the two simulated vents or groups <ret>, then to the base menu by entering 0 <ret> again.
of vents are numbered 1 (VENT NO. = 1 ) and 2 (VENT NO. =
2), that they are actuated by fusible links numbered 2 (FUSI­ With the base menu back on the screen, choose Option 2,
BLE LINK = 2) and 3 (FUSIBLE LINK = 3), respectively, and PHYSICAL PROPERTIES, to review and/or modifY the default
that each of the two vents or groups of vents has a total area of room property input data. Enter 2 <ret>.
96 ft2 (VENT AREA = 96.00000 IT2). C.5.3 Physical Properties. When Option 2, PHYSICAL PROP­
In the default fire scenario, it would be of interest to study ERTIES, of the base menu is chosen, the following physical
the effect of "ganging" the operation of all four vents (total properties menu is displayed:
area of 192 ft2 ) to fusing of the closest vent link. To do so, it MATERIAL = INSULATED DECK (SOLID POLYS1YRENE)
would be necessary to first remove vent number 2, as identified
in the preceding menu, and then to modify the area of vent HEAT CONDUCTIVITY = 2.400E-05 (BTU/S LB F)
number 1. HEAT CAPACITY = 2.770E-01 (BTU/LB F)
To remove vent number 2, enter 6 <ret>. The following is DENSITY= 6.550E+01 (LB/IT3)
now displayed on the screen:
ENTER NUMBER OF VENT TO BE ELIMINATED
l 80.00000 AMBIENT TEMPERATURE (F)
ENTER 0 TO RETURN TO MENU 2 0.50000 MATERIAL THICKNESS (FT)
3 MATERIAL = INSULATED DECK (SOLID
Now enter 2 <ret>. This completes removal of vent 2, with
POLYSTYRENE)
the following t-evision displayed on the so-een:
0 CHANGE NOTHING
VENT NO. = l FUSIBLE LINK = 2 VENT AREA = 96.00000
IT2 The values in Options l and 2 are modified by entering the
ENTER 6 TO REMOVE A VENT option number and then the new value.

ENTER VENT NO., LINK NO., AND VENT AREA (FT2) TO Now choose Option 3 by coding 3 <ret>. The following
ADD OR MODifY A VENT menu is displayed:

MAXIMUM NO. OF VENTS IS 5 1 CONCRETE

ENTER 0 TO RETURN TO THE MENU 2 BARE METAL DECK

Now modify the characteristics of vent number 1 . To do so, 3 INSULATED DECK (SOLID POLYS1YRENE)
enter 1 <ret>, 2 <ret>, 192. <ret>. The screen will now display 4 WOOD
the following:
5 0THER
VENT NO. = 1 FUSIBLE LINK = 2 VENT AREA = 192.00000
IT2 By choosing one of Options 1 through 4 of this menu, d1e
user specifies the material properties of the ceiling according
ENTER 6 TO REMOVE A VENT to the table of standard material properties in reference [4].
ENTER VENT NO., LINK NO., AND VENT AREA (FT2) TO vVhen the option number of one of these materials is chosen,
ADD OR MODIFY A VENT the material name, thermal conductivity, heat capacity, and
density are displayed on the screen as part of an updated physi­
MAXIMUM NO. OF VENTS IS 5 cal properties menu.

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 ANNEX C 204-49

Now choose Option 5, OTHER, by entering 5 <ret>. The MAXIMUM NUMBER OF LINKS EQUALS 10.
following screen is displayed:
ENTER 1 1 TO REMOVE A LINK.
ENTER MATERIAL NAME
ENTER 0 TO RETURN TO THE MENU.
THERMAL CONDUCfNI1Y (BTU /S FT F)
HEAT CAPACI1Y (BTU/LB F) DISTANCE
(FT)
DENSI1Y (LB/FT3)
RADIUS BELOW RTI SQRT FUSE
The four indicated inputs are required. Alter they are LINK# (FT) CEILING (FT S) TEMP (F)
entered, the screen returns to an updated physical properties
1 6.000 1 .000 400.000 165.000
menu.
2 21.200 0.300 50.000 165.000
Now return to the default material, INSULATED DECK 3 44.300 0.300 50.000 165.000
(SOLID POLYS1YRENE) . To do so, enter any arbiu·ary mate­
rial name with any three property values (enter .MATE­ Each fusible link must be assigned a link number (e.g., LINK
RlAL<ret>, 1 . <ret>, 1 . <ret>, 1 . <ret>) ; then choose Option 3, # = 1 ) , radial position from the plume-ceiling impingement
MATERIAL, from the menu displayed (enter 3 <t·et>) ; and, point (e.g., RADIUS = 6.00 FT), ceiling-to-link separation
from the final menu displayed, choose Option 3, INSULATED distance (e.g., DISTANCE BELOW CEILING = 1.00 FT),
DECK (SOLID POLYS1YRENE) by entering 3 <ret>. response time index (e.g., RTI = 400.00 SQRT[FT S l ) , and fuse
Now return to the base menu. Entet· 0 <ret>. Choose Option temperature (e.g., FUSE TEMPERATURE= 165.00 F).
3, OUTPUT PARAJ-..1ETERS, of the base menu to review or Suppose that in the default fixe scenario it was desired to
modifY the default output-parameter data. Enter 3 <ret>. simulate the thermal response of the group of (four) sprinkler
C.5.4 Output Parameters. When Option 3, OUTPUT links second closest to the fire. According to the description in
PARAMETERS, of the base menu is chosen, the following Section C.3 and in Figure C.3(a), this would be done by adding
output-parameters menu is displayed: a fourth link, link number 4, at a radial distance of 13.4 ft, 1 ft
below the ceiling, with an RTI of 400 (ft/sec) 112 and a fusion
temperature of 165°F. To do this, enter 4 <ret>, 13.4 <ret>, l .
400.000000 FINAL TIME (S) <ret>, 400. <ret>, 165.<ret>. Then the following screen is
2 30.000000 OUTPUT INTERVAL (S) displayed:
0 CHANGE NOTHING
TO ADD OR CHANGE A LINK, ENTER LINK NO.,
RADIUS (FT), DISTANCE BELOW CEILING (FT), RTI
FINAL TIME represents the ending time of the calculation. (SQRT[FT Sl ) , AND FUSE TEMPERATURE (F).
OUTPUT INTERVAL conu·ols the time interval between MAXIMUM NUMBER OF LINKS EQUALS 10.
successive outputs of the calculation results. All times are in
seconds. For example, assume that it is desired to run a fire ENTER 1 1 TO REMOVE A LINK.
scenario for 500 seconds with an output of results every
ENTER 0 TO RETURN TO THE MENU.
10 seconds. First choose Option 1 with a value of 500 (enter 1
<ret>, 500. <ret>), then Option 2 \'lith a value of 10 (enter 2
<ret>, 10. <ret>) . The following revised output-parameters DISTANCE
menu is displayed: (FT)
RADIUS BELOW RTI SQRT FUSE
UNK# (FT) CEILING (FT S) TEMP (F)
1 500.000000 FINAL TIME (S)
2 10.000000 OUTPUT INTERVAL (S) 1 6.000 1 .000 400.000 165.000
0 CHANGE NOTHING 2 13.400 1 .000 400.000 165.000
3 21.200 0.300 50.000 165.000
4 44.300 0.300 50.000 165.000
Return to the original default output parameters menu by
entering 1 <ret>, 400. <ret>, followed by 2 <ret>, 30. <ret>.
Note that the new link, which was entered as link number 4,
Now return to the base menu from the output parameters was sorted automatically into the list of the original three links
menu by entering 0 <ret>. and that aU four links were renumbered accot·ding to radial
distance from the fire. The original link-vent assignments are
'1\Tith the base menu back on the screen, choose Option 4,
preserved in this operation. Hence, the user need not return to
FUSIBLE LINK PROPERTIES, to review or modifY the defaLlit
Option 4, NUMBER OF VENTS, ETC., unless it is desired to
fusible link properties data. Enter 4 <ret>.
reassign link-vent combinations.
C.5.5 Fusible Link Properties. When Option 4, FUSIBLE
A maximum of 10 link responses can be simulated in any
LINK PROPERTIES, of the base menu is chosen, the following
one simulation.
fusible link properties menu is displayed:
Now remove link number 2 to return to the original default
TO ADD OR CHANGE A LINK, ENTER LINK NO.,
array of links. To do so, enter 1 1 <ret>. The following screen is
RADIUS (FT), DISTANCE BELOW CEILING (FT), RTI
displayed:
(SQRT[FT S l ) , AND FUSE TEMPERATURE (F).

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204-50 SMOKE AND HEAT VENTLNG

ENfER THE NUMBER OF THE LINK TO BE REMOVED To try Option 7, SPECIFY A CONSTANT DIAMETER FIRE
IN FEET, enter 7 <ret>. The following screen is displayed:
Enter 2 <ret> to remove link 2.
ENTER YOUR VALUE FOR FIRE DIAMETER IN FT
Now remrn to the base menu from the fusible link proper­
ties menu by entering 0 <ret>. A�sume the fire diameter is fixed at 5 ft. Enter 5. <ret>. Then
the following screen is displayed:
W'ith the base menu back on the screen, choose Option 5,
FIRE PROPERTIES, to review or modifY the default fire proper­
ties data. Enter 5 <ret>. 1 2.50000 FIRE HEIGHT (FT)
2 5.00000 FIRE DIAMETER (FT), ETC.
C.5.6 Fire Properties. \<\'hen Option 5, FIRE PROPERTIES,
from the base menu is chosen, the following fire properties 3 FIRE OUTPUT AS A FUNCTION OF TIME
menu is displayed: 0 CHANGE NOTHING

Now return to the original default fire properties menu by

l 2.5 FIRE HEIGHT (FT) entering 2 <ret>. The previous menu will be displayed. In this,
2 330.0 FIRE POWER/AREA (BTU/S FT2), ETC. choose Option 1, WOOD PALLETS, STACK, 5 ft high, by entet·­
3 FIRE OUTPUT AS A FUNCTION OF TIME ing 1 <ret>.
0 CHANGE NOTHING
Option 3, FIRE OUTPUT AS A FUNCTION OF TIME, of
the fire properties menu allows the user to prescribe the fire as
The value associated with Option 1 is the height of the base a function of time. The prescription involves: ( 1 ) linear inter­
of the fire above the floor. Change this to 3 ft, for example, by polation between adjacent pairs of user-specified points with
entering 1 <ret> and 3. <ret>. Then remrn to the default data coordinates (time in seconds, fit·e energy release rate in BTU/
by entering 1 <ret> and 2.5 <t·et>. sec); and (2) continuation of the fire to an arbitrarily large
The value associated with Option 2 is the fire energy release time at the fire energy release rate of the last data point.
rate per fire area. It is also possible to consider simulations Now choose Option 3 by entering 3 <ret>. The following
where the fire area is fixed by specifYing a fixed fire diameter. screen associated with the default fire output data is displayed:
The fire energy release rate per fire area can be changed, or
the fixed fire area type of specification can be made by choos­
ing Option 2 by entering 2 <ret>. This leads to a display of the 1 TIME(s) = 0.00000 POWER(BTU/S) = O.OOOOOE+O
following menu: 2 TIME(s) = 100.0000 POWER(BTU/S) = 0.59200E+03
3 TIME(s) = 200.0000 POWER(BTU/S) = 0.23670E+04
4 TIME(s) = 400.0000 POWER(BTU/S) = 0.94680E+04
WOOD PALLETS, STACK, 330 (BTU/S FT2)
5 TIME(s) = 600.0000 POWER(BTU/S) = 0.21302E+05
5 FT HIGH
6 TI.ME(s) = 747.0000 POWER(BTU/S) = 0.33000E+05
2 CARTONS, COMPARTMENTED, 200 (BTU/S FT2)
STACKED 15 FT HIGH
3 PE BOTTLES IN 540 (BTU/S FT2) ENTER DATA POINT NO., TIME (S), AND POWER
COMPARTMENTED CARTONS (BTU/S)
15 FT HIGH ENTER 1 1 TO REMOVE A POINT
4 PSJARS IN COMPARTMENTED 1300 (BTU/S FT2)
CARTONS 15 FT HIGH ENTER 0 TO RETURN TO MENU
5 GASOLINE 200 (BTU/S FT2) As discussed in Section C.3, with use of the six preceding
6 INPUT YOUR OWN VALUE IN data points, the default simulation will estimate the fire's
(BTU/S FT2) energy release rate according to the plot of Figure C.3(b).
7 SPECIFY A CONSTANT
DIAMETER FIRE IN FT Additional data points can be added to the fire growth simu­
0 CHANGE NOTHING lation by entering the new data point number, <ret>, the time
in seconds, <ret>, the energy release rate in BTU/sec, and
<ret>.
Options 1 through 5 of the preceding menu are for variable
area fires. The Option 1 to 5 constants displayed on the right The maximum number of data points permitted is 10. The
are the fire energy release rate per unit fire area. They are points can be entet·ed in any order. A sot·ting routine will ot·der
taken from Table 4.1 of reference f l l . If one of these options is the points by time. One point must correspond to zero time.
chosen, an appropriately updated fire properties menu is then
A� an example of adding an additional data point to the
displayed on the screen. Option 0 would lead to the remrn of
preceding six, a5sume that a closer match to the "t-squared"
the original fire properties menu.
default fire growth curve was desired between 200 seconds and
Option 6 allows any other fire energy release rate per unit 400 seconds. From Section C.3 it can be verified that the fire
fire area of the user's choice. Option 7 allows the user to specif)' energy release rate will be 5325 BTU/sec at t = 300. To add this
the diameter of a constant area fire instead of an energy release point to the data, thereby forcing the fire growth curve to pass
t·ate per unit area fire. Choice of Option 6 ot· 7 must be exacdy through the "t-squared" curve at 300 seconds, enter 7
followed by entry of the appropriate value. Then an appropri­ <ret>, 300. <ret>, and 5325. <ret>. The following t·evised screen
ately updated fire properties menu appears on the screen. will be displayed:

2021 Edition
 ANNEX C 204-51

1 TIME(s) = 0.0000 POWER(BTU/S) = O.OOOOOE+OO is potential for the solvers to become incompatible vvith each
other, particularly if the upper layer has nearly reached a
2 TIME(s) = 100.0000 POVlER(BTU/S) = 0.59200E+03
steady-state temperature but the ceiling is still increasing its
3 TIME(s) = 200.0000 POWER(BTU/S) = 0.23670E+04
temperature. When this occurs, the differential equation solver
4 TIME(s) = 300.0000 POWER(BTU/S) = 0.53250E+04
will try to take time steps that are too large for the Gauss-Seidel
5 TIME(s) = 400.0000 POWER(BTU/S) = 0.94680E+04 solver to ha.t1dle, and a growing oscillation in the ceiling
6 TIME(s) = 600.0000 POWER(BTU/S) = 0.21302E+05 temperature variable might occur. By reducing the FLUX
7 TIME(s) = 747.0000 POWER(BTU /S) = 0.33000E+05 UPDATE INTERVAL, the gmwing oscillation can be
suppressed. The smaller the FLUX UPDATE fNTERVAL, the
ENTER DATA PT. NO., TIME (S), AND POWER (BTU/S) slower the code will run.
ENTER 1 1 TO REMOVE A POINT The GAUSS-SEIDEL RELAXATION coefficient can be
changed to produce a faster running code or to handle a case
ENTER 0 TO RETURN TO MENU that will not run with a different coefficient. Typical values of
Note that the revised point, which was entered as point this coefficient should range between 0.2 and 1.0.
number 7, has been resorted into the original array of data The DIFF EQ SOLVER TOLERANCE and the GAUSS­
points and that all points have been renumbered appropriately. SEIDEL TOLERANCE can also be cha.t1ged. Decreasing or
Now remove the point just added (which is now point increasing these values can provide a faster nmning code for a
number 4). First enter 1 1 <ret>. Then the following screen s
i given case, and by decreasing the value of the tolerances, the
displayed: accuracy of the calculations can be increased. If the tolerance
values are made too small, the code will either nm very slowly
ENTER THE NUMBER OF THE DATA POINT TO BE or not run at all. Suggested tolera.t1ces would be in the range of
REMOVED 0.00001 to 0.000001 .
Now enter 4 <ret>. This brings the fire growth simulation Consistent with the model assumptions, accuracy in the
data back to the original default set of values. radial ceiling temperamre disu-ibution around the plume­
ceiling impingement point is dependent on the NUMBER OF
Now return to the fire properties menu. Enter 0 <ret>. Then
CEILfNG GRID POINTS. Relatively greater m- lesser accuracy
return to the base menu by entering again 0 <ret>.
is achieved by using relatively more or fewer grid points. This
With the base menu back on the screen, it is assmned that leads, in turn, to a relatively slower or faster computer run.
the inputting of all data required to define the desired fire
C.6 File Status - Running the Code. When Option 0, NO
simulation is complete. Now choose Option 0, NO CHANGES,
CHANGES, of the base menu is chosen, the following file status
to proceed to the file status menu. Enter 0 <ret>.
menu is displayed:
C.5.7 Solver Parameters. Users of the code will generally have
no need to refer to this section (i.e., especially when learning
to use the l.AVENT code, a user should now skip to 1 SAVE THE FILE AND RUN THE CODE
Section C.6), since they are rarely, if ever, expected to run into 2 SAVE THE FILE BUT DON'T RUN THE CODE
a situation where the code is not able to obtain a solution for a 3 DON'T SAVE THE FILE BUT RUN THE CODE
particulat- application 01- is taking an inordinate amount of 4 ABORT THE CALCUlATION
time to produce the solution. Howevet� if this does happen,
there are a number of variations of the default solver para.tne­ If one of the save options is selected, the user will be asked
ter inputs that can resolve the problem. to supply a file na.tne to designate the file where the newly
generated input data are to be saved. The program will auto­
Start the input part of the program to get to the base menu.
matically create the new file. File na.tnes may be as long as eight
Then choose Option 6, SOLVER PARAMETERS, by entering 6
characters and should have a common extender such as .DAT
<ret>. The following input options menu will be displayed:
(for example MYFILE.DAT). The maximum length that can be
used for the total length of input or output files is 25 charac­
1 0.6500E+00 GAUSS-SEIDEL RELAXATION ters. For exa.tnple, C:\SUBDfRECI\FILENAME.DAT would
2 O. l OOOE-04 DIFF EQ SOLVER TOLERANCE allow a file named FILENAME.DAT to be read from the subdi­
3 0.1000E-04 GAUSS-SEIDEL TOLERANCE rectory SUBDIRECT on the C drive. To read a file from a
4 2.000000 FLUX UPDATE INTERVAL (S) floppy disk in the A drive, use A:FILENAME.DAT If Option 4 is
5 6 NUMBER OF CEILING GRID chosen, the program will end without any file being saved.
POfNTS, MfN=2, l\1AX=50 A t-equest for an output file na.tne can appear on the screen.
6 0.1000E-07 SMALLEST MEANINGFUL VALUE File na.tnes can be as long as eight cha.t-acters and should have
7 CHANGE NOTHING an extender such as ".OUT" so that the output files Ca.t1 easily
be t-ecognized. To output a file to a floppy disk in the A (lt-ive,
The solvers used in this code consist of a differential equa­ name the file A:FILENAME.OUT. To output a file to a subdi­
tion solver DDRIVE2, used to solve the set of differential equa­ rectory other than the one that is resident to the progra.tn, use
tions associated with the layer and the fusible links, and a C:\SUBDIRECI\FILENAME.OUT for the subdirectOt)'
Gauss-Seidel/u·idiagona.l solver using the Crank-Nicolson SUBDIRECT.
formalism to solve the set of partial differential equations asso­ Once the output file has been designated, the progra.tn will
ciated with the heat conduction calculation fOt- the ceiling. begin to execute. The statement PROGRAM RUNNING 'vill
Because two different solvers are being used in the code, there appear on the screen. Each time the program writes to the

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204-52 SMOKE AND HEAT VENTLNG

output file, a statement such as T = 3.0000E01 S will appear on 9 JET VELOCITY AT LINK
the screen to provide the user with the present output time. 10 JET TEMPERATURE AT LINK
C.7 The Output Variables and the Output Options. The
program generates two separate output files. An example of Two plots can be sntdied on a single screen. For example,
the first output Hie is appended at the end of d1is document. from the default simulation, assume that displays of the plots of
This file is named by the user and consists of a listing of the Figure C.7(a) and Figure C.7(b), LAYER HEIGHT vs. TIME
input data plus all the relevant output variables in a format and LAYER TEMPERATURE vs. TIME, respectively, are
where the output units are specified and the meanings of all desired. Then enter 1 <ret>, 3 <ret>, 1 <ret>, and 2 <ret>. The
but three of the output variables are clearly specified. These program will respond with the following prompt:
latter variables are TSL, QB, and QT, the temperature of the ENTER THE TITLES FOR THE TWO GRAPHS, 16 CHAR­
ceiling inside the enclosure, the net heat transfer flux to the ACTERS MAX.
bottom surface of the ceiling, and the net heat transfer flux to
the top surface of the ceiling, respectively. The variables are The user might choose titles that would identifY particular
output as a function of radius, with R = 0 being the center of cases such as LY HT RUN 100 <ret> and LY TEMP RUN 100
the fire plume projected on the ceiling. Other abbreviations <ret>. If a tide longer than 16 characters s i chosen, it will be
include LYR TEMP, LYR HT, LYR MASS, JET VELOCilY, and truncated to 16 characters. After the titles have been entered,
JET TEMP - the upper·layer (layer adjacent to the ceiling) the program will respond with the following prompt:
ternperature, height of the upper-layer interface above the
floor, mass of gas in the layer, ceilingjet velocity, and ceilingjet ENTER 1 FOR DEFAULT SCALING, 2 FOR USER SCAI.r
temperanu-e at the position of each fusible link, respectively. ING.
The VENT AREA is the total area of roof vents open at the time If the user chooses option l , the desired plots will appear on
of output. the screen with an internal scaling for the » and )'-axis of each
The second output file, GRAPH.OUT, is used by the graph­ graph. If the user chooses option 2, the program will respond
ics program GRAPH. GRAPH s i a Fortran program that makes with the following prompt:
use of a graphics software package to produce graphical output ENTER THE MINIMUM AND MAXIMUM VALUES FOR
of selected output variables [5, 61 . To use the graphics THE X AND Y AXIS OF EACH GRAPH.
program, the file GRAPH.OUT must be in the same directory
as the program GRAPH. GRAPH is a menu-driven program ENTER 0 FOR THE MINIMUM AND MAXIMUM VALUES
that provides the uset- with the ability to plot two sets of varia­ OF EACH AXIS WHERE DEFAULT SCALING IS DESIRED.
bles on the PC screen. An option exists d1at permits the user to FOR EXAMPLE, VALUES SHOULD BE ENTERED AS
print the plots from the screen to a printer. If using an attached 0.,100.,0.,200.,10.,50.,20.,100.<ret> FOR X1 (0-100), Yl (0-200) ,
EPSON-compatible printer, enter <ret> to produce a plot using X2( 10-50) , Y2(20-100).
the printer. To generate a PostScript file for use on a laser Use of this option allows a number of different cases to be
printer, enter <ret> and provide a file name when the file name compared using similat- values for the x- and y-axis of each
prompt appears in the upper left hand corner of the graph. To graph. All eight numbers must be entered and separated with
exit to screen mode from the graphics mode, enter <ret>. The commas before entering <ret>. Once the entry is made, the
file GRAPH.OUT will be desu-oyed each time the code plots will appear on the screen. Note that this option permits a
LAVENT is run. If the user wishes to save the graphics file, it mixture of default scaling and user-specified scaling.
must be copied using the DOS copy command into another file
vvith a different file name. Once a pair of plots are displayed on the screen, the user
would have the choice of entering <t-et> to obtain a hard-copy
To demonstrate the use of GRAPH, start the program by plot of the graphs or of entering <ret> to exit the graphics
entering graph <ret>. GRAPH will read in the graphics output mode.
file GRAPI-I.OUT, and the following screen will be displayed:
To plot a second pair of graphs, the user would exit the
ENTER 0 TO PLOT POINTS, ENTER 1 TO PLOT AND graphics mode by entering <ret> and then repeat the preced­
CONNECT POINTS ing process by entering graph <ret>, and so forth.
The graphics presented in Figure C.7(a) through Figure If the user selects plots that involve variables defined by
C.7(e) wet-e done with GRAPH using option 0. Enter 0 <ret> Option 8, 9, or 10, d1en, following the enu-y 8 <ret>, 9 <ret>, or
and the following graphics menu is displayed: 10 <ret>, the following prompt for identifYing the desired link
ENTER THE X AND Y VARIABLES FOR THE DESIRED number (in the default simulation with three simulated links)
TWO GRAPHS will be displayed immediately:
ENTER LINK NUMBER, MAXIMUM NUMBER = 3
1 TIME The uset- would then enter the desired link number followed
2 LAYER TEMPERATURE by <ret> and continue entering the remaining input data that
3 LAYER HEIGHT define d1e desired plots.
4 LAYER MASS
5 FIRE OUTPUT As an example of generating link-related plots, consider
6 CEILING VENT AREA displaying the pair of plots LINK TEMPERATURE vs . TIME
7 PLUME FLOW and JET VELOCilY AT LINK vs. TIME for link number 3 in
8 LINK TEMPERATURE the default simulation. First enter 1 <ret> (for TIME on the x­
(continues)
axis) and 8 <ret> (for LINK TEMPERATURE on d1e )'-axis). At

2021 Edition
 ANNEX C 204-53

this point, "ENTER LINK NUMBER . . . " would be displayed on 3 4 0 .--.--r-.--r--,--,

the screen. Continue by entering 3 <ret> (for link number 3).
This would complete the data entry for the first of the two 320
plots. For the second plot, enter 1 <ret> (for TIME on the x­
axis) and 9 <ret> (for LINK TEMPERATURE on the y-axis). At 300
this point, "ENTER LINK NUMBER . . . " would be displayed a
280
second time. Then conclude data input for the pair of plots by
entet-ing 3 <ret> (for link number 3). At this point the desired
pair of plots would be displayed on the screen.
� 260
C.8 An Example Simulation - The Default Case. This � 240
::I
section presents and reviews briefly the simulation of the ...,
default case. � 220
Illn.
The tabular output of the default simulation is presented in ffi 2 0 0
Figme C.4. Plots of the layer-interface height and of the layer
...,
•
temperamre as functions of time are plotted in Figure C.7(a) �:>. 1 8 0
Ill
and Figure C.7 (b), respectively. Plots of the thermal response ..:l
of the two pairs of vent links and the pair of sprinkler links clos­ 160
est to the fire are presented in Figure C.7(c) through Figure
C.7(e), respectively. 140 •

From Figure C.4 and Figure C.7(c) through Figure C.7(e), it 120
is seen that the sequence of Link fusing (at 165°F) is predicted
to be the near pair of vents at 187 seconds, the far pair of vents 100
at 267 seconds, and the pair of closest sprinklet-s at
8 0 L--i
--� __L__i__ _L __ L_ _i
�
283 seconds. Although the sprinkler Links are closer to the fire 0 100 200 300 400
than any of the vent links, and although all links have the same Time ( s e c )
fuse temperatures, the simulation predicts that the spt-inkler
Links fuse after all of the vent links. There are two reasons for FIGURE C.7(b) Plot of the Temperature of the Smoke
this. First, the RTis of the sprinkler links are larger than those Layer vs. Time for the Default Simulation.
of the vent Links and, therefore, slower to t-espond thermally.
Second, the two sprinkler links simulated are far enough from
the ceiling as to be below the peak temperature of the ceiling
jet, which is relatively thin at the 6 ft radial position (see the
lower sketch ofFigme C.2).

350
30

29
300

28
Ill •
27 � 250
...,
Ill
...
..., 26 Illn.
....
ffi 2 0 0
..., ...,
..c: 25 -"
0> • • a
..... .....
Ill
..c: • H
24 150
...
Ill:>.
Ill 23
..:l
100
22

21
5 0 L--i
--� L_
__ _i__ � __ L_ _L
�
0 100 200 300 400
20 Time ( sec )

19
FIGURE C. 7(c) Plot of the Closest (R = 21.2 ft) Vent-Link
0 100 200 300 400 Temperature vs. Time for the Default Simulation.
Time ( sec)

FIGURE C.7(a) Plot of the Height of the Smoke Layer

Interface vs. Time for the Default Simulation.

2021 Edition
204-54 SMOKE AND HEAT VENTLNG

2 8 0 .-�---r--.---.-�---r--�-. The effect on layer growth of fusing of the two pairs of vent
links and opening of their cotTesponding vents at 187 seconds
260
and 267 seconds can be noted in Figure C.7(a). Note that the
•
opening of the first pair of vents effectively stops the rate-of­
increase of layer thickness and the opening of the second pair
240 of vents leads to a relatively rapid rate-of-decrease in the layer
•
thickness. All of this is of course occurring at times when the
220
energy release rate of the fire is growing rapidly.
As can be seen in Figure C.7(a), up tmtil the 400 seconds of
•

200 simulation time, the smoke is still contained in the original

(l)
1-< curtained compartment and has not "spilled over" to adjacent
::l
...,
spaces. From this figure it appears that with no venting, the
� 180
(l) layer would have dropped below the bottom of the curtain
ffi
..., 160
boards prior to fusing of the first sprinkler links. This could be
confirmed with a second simulation run of LAVE NT, where all
�s:: vent action was removed from the default data.
·.-<
..:l
140 C.9 References for Annex C. 1. Cooper, L. Y., and D. W.
Sn·oup. "Thermal Response of Unconfined Ceilings Above
Growing Fires and the Importance of Convective Heat Trans­
120
fer," joumal ofHeat 11-ansfer 109: 172-178, 1987.
2. Evans, D. D. "Calculating Sprinkler Actuation Times in
100
Compartments," Fire Safetyjowrnal 9:147-155, 1985.
3. Evans, D. D., and D. W. Sn·oup, "Use of Computer Fire
100 200 300 400 Models for Analyzing Thermal Detector Spacing," Fire Safety
Time ( sec ) Joumal 14:33-45, 1988.

FIGURE C.7(d) Plot o f the Far ( R = 44.3 ft) Pair o fVent­ 4. Gross, D. "Data Sources for Pammeters Used in Predictive
Link Temperatures vs. Time for the Default Simulation. Modeling of Fire Growth and Smoke Spread," NBSIR 85-3223,
National Bureau of Standards, Gaithersburg MD, September
1985.
2 6 o .--.--.---.--, 5. Kahaner, D., C. Moher, and S. Nash. Numerical Methods and
Software, Prentice Hall, New York, NY, 1989.
240 6. Kahanet� D., National Institute of Standards and Technol­
ogy, private communication.

220
Annex D Sample Problem Using Engineering Equations
(Hand Calculations) and !AVENT
f: 2 0 0 This annex is not a part of the requirements of this NFPA document
but is includedfat· infonnational pwposes only.
(l)
� 180 D.l Abstract. The following example problem illustrates the
...,
ro
1-< use of the information, engineering equations, hand calcula­
(l)
tions, and computer model described in this document. The
ft 1 6 0
(l) impact of a fire on a nonsprinklered retail storage building and
...,
�s:: its occupants is assessed. The effects of an anticipated fire on
j 140 the subject building are predicted, and the impact of smoke
and heat vents is illustrated.
Design goals and objectives were developed, and a high­
120
challenge fire, likely to occur in the subject building, was iden­
tified. The fire impact was assessed using three different
100 methods:
(1) Hand calculations assuming a quasi-steady fire
(2) Hand calculations assuming a continuous-gt·owth
100 200 300 400 (t-squared) fire
Time ( se c ) (3) The computer model LAVENT

FIGURE C.7(e) Plot of the Closest (R = 6 ft) Sprinkler-Link

Temperatures vs. Time for the Default Simulation.

2021 Edition
 ANNEX D 204-55

Hand calculations are useful for generating quick estimates

of the impact of vents on fire effects. However, hand calcula­
tions are not able to assess time-varying events. A number of
simplifying assumptions have been used to facilitate problem
solving via algebraic equations. Hand-calculated results are
considered valid, but they produce slightly different estimates
of fire effects such as upper-layer temperantre. A computer
model such as LAVENT generally provides a mNe complete
analysis of the fire-produced effects and, in some instances, is
preferable over hand calculations.
73 m
D.2 Introduction. The following example problem illustrates
the use of engineering equations and a computer model to
assess the impact of a fire in a nonsprinklered retail storage
building. The problem illustrates the impact of vents and
predicts the effect of the anticipated fire on the building.
D.2.1 Goal. Develop a vent design for the subject building
that will maintain a tenable environment for a period of time at
least equal to the time required to evacuate the building and lliiliill lliiliill
equal to the time required to maintain the hot upper layer a m.mill �
minimwn of 3 m above flo01- level until the local fire depart­
ment enters the building.
D.2.2 Objective. Determine the vent area required to main­
73 m
tain the smoke layer at least 3 m above floor level for
300 seconds following detection of the fire by an automatic FIGURE D.2.3 Vent Plan View.
detection system. Also, limit the heat flux at floor level to a
maximum of 2.5 kW/m2 , the threshold irradiance that causes
severe pain to exposed skin [ 1 1 , during the time required for
evacuation of the building occupants. D.3 Fire Growth. First, an estimate of the anticipated fire
D.2.3 Buililing Details. The building is 73 m wide, 73 m long, growth must be developed. A t-squared fire will be assumed (see
and 9.1 m high. It is not subdivided, nor is it provided with a 8.3.1 andA.8.3.1). In a 1-squared fire,
sprinkler system. The roof is an insulated deck (solid polysty­
rene). A complete fire alarm system is to be installed using heat
[D.3a]
detectors spaced 15.2 m on center and 6.1 m from walls. Detec­
tors will have an activation temperature of 74°C and an RTI of
55 (m·sec) 112 and are to be located 0.3 m below the roof.
Sixteen vents are proposed, spaced 18.3 m on center. Vents will where:
be located 9.05 m from walls. The vents will be activated by fusi­ Q = total heat release rate (kW)
ble links with an activation temperarure of 74°C and an RTI of ag = fire growth coefficient
28 (m·sec) 112 and are to be located 0.3 m below the roof. Inlet t = time (seconds)
air openings will be equal to 1.5 the total vent area. (See Figun:
The data base within Hazard I [2] contains data from furni­
D.2.3.)
tme calot·imeter tests of sofas. A sofa (UPS001 ) was tested and
D.2.4 Occupancy Details. The building is to be occupied for demonstrated a growth time (tg) to 1 MW of approx imately
retail storage. This analysis deals with a fire in rack storage of 200 seconds. The fire in the sofa in this example is assumed to
sofas in the center of the building. The sofas are to be stored in have a gwwth time of 150 seconds to 1 MW as a reasonable,
two racks, each 9.75 m long and 1.2 m wide and separated from conservative approximation of the anticipated fire in the sofas
each other by 2.4 m. Each t·ack will have fom tiers of storage, stored in the example building. If a more precise estimate of
four sofas per tiet� and a total storage height of 7.6 m. Distance the bw·ning characteristics of an individual sofa is necessary,
to combustibles surrounding the racks will be sufficient to the exact sofa to be stored in the building could be tested in a
prevent fire spread to those combustibles during the time calorimeter. A fire growth time of 150 seconds results in an a
period covered by this analysis. The sofas are identified as for the individual sofa of 0.044 kW/sec2 (see Aquation 8.3.2 /
specimen F32 contained within Table E.5.3(d). Data for the That is,
same sofas are conrained 'vithin a database of Hazard I [2] ,
where the sofas are identified as specimen UPSOOl . Each sofa
[D.3b]
will contain 51.5 kg of combustible mass and be wrapped in
polyethylene.
D.2.5 Ignition. An ignition is assumed to occur in a sofa on
the first tier of one of the racks. Ignition of a sofa on the first
tier is a pt-obable worst-case scenario and, a� a practical matter, Accordingly, fire growth in the first sofa ignited can be
is a location where ignition could be expected. Also, placing approximated by a fast (ag = 0.044 kW/sec 2) t-squared fire.
the fire near floor level results in near-maximum smoke Furthet� according to 8.3.1, ag is directly proportional to the
production (eno-ainment). storage height. Therefore, the fire growth constant (ag) for

2021 Edition
204-56 SMOKE AND HEAT VENTLNG

sofas stacked four high is 4 times 0.044 kW/sec 2, or a� equals [D.3i]

0.18 kW/sec2, and initial fire growth is approximated as Q_ = 32(3120) :: 100 MW

[D.3c] The time, tmax> to reach 100 MW must be determined using

the following:

where ag= 0.18 kW/sec2. [D.3j]

Fire growth in the first rack of sofas results in radiant heat Q,,.x = 0.36(t - 39)2
transfer to a second rack of sofas separated from the first rack
by 2.4 m. It must be determined when the second rack of sofas When Q= 100,000 kW,
ignite. The fire size, when ignition of the second rack of sofas
occurs, is determined using Equation 8.2.3 with its terms rear­
ranged:
[D.3k]

100,000 = 0.36(t.,.,.x -39t

[D.3d]

12
w
Q= [D.3J]
0.0422
(1 00,000)
t.,," = + 39 = 566 sec
where: 0.36
Q = fire output (kW)
W = aisle width (m) An estimate of fire duration, tmm is now made using data
from the Hazard I [2] database for sofa UPS001 , where individ­
Next, the time of ignition of the second rack is computed: ual sofa combustible mass = 51.5 kg, sofa effective heat of
combustion = 18,900 kJ/kg, and maximum fire size =

t=
[ )1 ( )1
_R
/
2 3250
= -
9

I-
= 134 sec
[D.3e] 100,000 kW.
The mass consumed from t = 0 to t = 134 seconds is deter­
mined from the total heat release as follows:
ag 0.18

where Q= a/.
V1lhen the second rack of sofas is ignited at 134 seconds, the
1J3< 1 0 18 3
Qdt = -'- t
1 13<1 0 18
=-'- (134)3 = 144,366 kj
[D.3m]

fire growth coefficient, ag, for the twu racks burning together is 0
3 0 3
assumed to double the value for the first rack burning alone
(ag= 0.36 kW/sec2) . At that time, the fire appears to have origi­ Since Q = 1hh, (see Equation E.3a), mass loss, f'.. m, for t =
nated at effective ignition time, 4:!,. For t >134 seconds, 134 seconds, is determined as follows:

[D.3f] [D.3n]
144,366 kj
11 m = = 7.6 kg ot· : 8 kg
18,900 kj/kg
Determine 4Jg as follows:
The mass consumed from t = 134 seconds to t.,{L, the time
the maximum fire size is reached, is similarly determined from
[D.3g] the total heat t·elease rate after 134 seconds, as follows:

[D.3o]
where t0g = 39 seconds. Then, for t > 134 seconds,
t,.r
134
Q dt = T
134
0.36(t -39/ dt = 566r
134-39
0 6
0.3$2dl3= · 3 (t
3
lj ��,
[D.3h]
Total heat release from t = 134 to t = 566 is then =
Q = 0.36(t- 39)2
0.12r (527)3 - (95)3) = 17,460,697 kj, and the mass lost, f'..rn, is
f'..m = 17,460,697 kj/ 18,900 kj/kg = 923.8 � 924 kg.
The maxirnum fire size is now estimated. Sofa UPS001 from
the Hazard I database [2] [specimen F32 in Table E.5.3(d)) Approximately (924 + 8) kg= 932 kg is consumed during the
has a peak burning rate of 3120 kW. Maximum fire size, Q,, , is
based on the assumption that all 32 sofas are burning at their
.
• 566 second time intet·val required to reach Q,.,{L,. The total
combustible mass is 51.5 kg x 32 = 1648 kg. Therefore, around
individual peak rates, 3120 kW: (1648 - 932) kg = 716 kg is available to burn at Q = Q,nax = 100
�1\1, after t = 566 seconds, from which the fire duration can be
calculated as follows:

2021 Edition
 ANNEX D 204-57

have an activation temperature of 74°C, and have an RTI of 55

[D.3p] (m·sec) l/2. Assuming the anticipated fire is as described, the
Q,..x(t,"1 - 566) = lOO,OOO(t,,d - 566) = 716(18,900) max imum distance from a detector to the fire axis is the diago­
nal r2( 15.2/2) 2 ] l/2 10.7 m, the ambient temperature is 21 oc,
=

and the fire is 0.5 m above floor level, DETACf-QS predicts the
activation of a heat detector at 230 seconds. In the event
quicker detection is judged to be necessary, smoke detector
[D.3q]
716(18•900) activation can be predicted by DETACf-QS using the guidance
tn>d = 566+ 701.3 seconcls = 700 sec
100,000 provided in A.9.2.5.4.4.1. Detection time for smoke detectors is
based on the gas temperature rise at the detector site. Smoke
The combustible mass of the sofas alone is able to support detector activation can be approximated using DETACf-QS,
the anticipated fire for approximately 700 seconds. In reality, assuming the smoke detector will respond like a heat detector,
the fire in the sofas would reach a maximum of 100 l\1vV at which has a small RTI [e.g., 1 (m·sec) 112] and a certain activa­
550-600 seconds and burn briefly at the 100 M'N peak until the tion temperature above ambient (see A.9.2.5.4.4.1). Tests involv­
combustible mass available began to be consumed, at which ing burning of the sofa upholstery with the actual detector to
time the fire's t·ate of heat release would begin to decline. be installed have determined that 10°C above ambient is a
Using a t,,J of 700 seconds is conservative. representative activation condition. Assuming smoke detectors
are spaced 9.1 m on center (located a maximum of 6.5 m from
In summary, the analysis to this point leads to the following the axis of the fire ) , smoke detector activation is predicted by
estimate for the anticipated fire: DETACf-QS at 48 seconds.
Using DETACf-QS, vent operation is predicted using fusible
[D.3r] links having an activation temperature of 74°C and an RTI of
Q = 0.18t2 for 0 < t $ 134 sec 28 (m·sec) 11 2. Assuming the anticipated fire is located in the
2 center of the building, the ambient temperature is 21 °C, and
Q = 0.36(t- 39) for 134 < t $ 566 sec assuming the fire is 0.5 m above floor level, activation of the
Q = 100,000 kW for t > 566 sec first vents (equidistant from the fire) separated [2(18.3/2) 2) 112
=
12.9 m from the fire is predicted by DETACf-QS at
(See Fig-ure D.3.) 228 seconds. The next set of vent� (equidistant from the fire at
28.9 m) are predicted to open at 317 seconds. Similarly, the
D.4 Fire Detection. The time of fire detection is now calcula­ third set of four vents, 38.8 m from the fire axis, open at
ted given the fire and building as described. The time of detec­ 356 seconds. All 16 vents are open at 356 seconds. Alternatively,
tion will be estimated based on the actual composite fire if fusible links having the same RTI as the heat detectors [55
already described. Detection time can be calculated using (m·sec) 1121 are used, all vents are predicted to be open at
Equation 9.2.5.4.3. DETACT-QS (see A.9.2.5.4.4.2) is a readily 384 seconds.
available computational tool that performs this calculation.
D.5 Vent Design. Of main concern in this example is the
A complete fire alarm system is to be installed using heat temperature of the smoke layer, which governs the heat flux
detectors that are spaced 15.2 m on center (6.1 m from walls), radiated to the floor. Assuming an emissivity of l and a configu-

120

0
0
100
0

X
� 80
�
Q)
"'
"'
Q) 60
�
en
Q)
.J::
40
0
Q) q 0.36(�2 for t x134 and
=

en
a: 20 q 0.36(1- 39)2 for 1>134
=

0
100 200 300 400 500 600 700 800
Time (sec)
FIGURE D.3 Fire Output.

2021 Edition
204-58 SMOKE AND HEAT VENTLNG

ration factor of 1 , the radiant heat flux at the floor is calculated which is greater than the height of the smoke layer. (It is
as follows: even greater than the ceiling height so that the flames will
impinge on the ceiling and flow radially outward.) Therefore,
the mass flow rate in the plume as it enters the smoke layer is
[D.5]
calculated from Equation 9.2.3.7, as follows (assuming Q,. =
0.7Q):

where:
[D.6d]
Fluxjl = (5.67 X 10" 11 ) T4kW/m 2
k= 5.67 X 10"1 1 kW/m2 K4 25
Stefan-Boltzmann constant = mP = 0.0056(0.7x100,000) · = 62.8 kg/sec
E= emissivity = 1 15.6
P= configuration factor = 1
T= temperature of the layer (K) Now the temperature rise in the smoke layet· can be estima­
ted using Equation 9.2.4.3, with Cp = 1.00 kJ/kg·K and the value
For a fltLx limit of 2.5 kW/m2 , as stated in the objective, the of K = 0.5 recommended in 9.2.4.4.
temperature of the smoke layer is calculated as 458 K, or 164 K
above the ambient temperature of 294 K.
[D.6e]
D.6 Steady Fire - Smoke Layer Temperature. First, condi­
0.5(70,000)
tions following attainment of the maximum heat release rate of !1T = 557 K
100 MW can be examined (i.e., at times greater than 1 .00(62.8)
566 seconds) assuming a smoke layer at the lowest acceptable
height, 3 m above the floor. (The heat detector installation This value is considerably above 164 K; therefore, the floor
contemplated was calculated to provide alarm at 230 seconds; radiant heat flux can be expected to be much higher than the
300 seconds following detection places the time of interest at limit 2.5 kW/m2 • Using the equation for radiant heat flux to
530 seconds, close to the attainment of the maximum heat the floor presented previously, the value 29.7 kW/m2 is calcula­
t·elease rate.) ted for a smoke layer temperatw-e of 557 + 294 = 851 K.

The effective diameter of the fire is required for the calcula­ Not only is the smoke layer temperamre, 557 + 21 = 578°C,
tions. This diameter can be determined with the aid of Equa­ so high that it produces unacceptable levels of radiant flux at
tion 8.3.7, setting Q = 100,000 kW and selecting an appropriate the floor, but it is also close to the level, 6000C, where fire can
value for the heat release rate per unit floor area, Q11• The tw·o flash over all the combustibles under the smoke layer. Further­
racks facing each other across the 2.4 m wide aisle are 9.75 m more, it exceeds the value, 540°C, where unprotected steel
long and 1.2 m wide (see Figure D.6). The heat release rate per begins losing strength. Directly over the fire the temperatures
unit area is taken as the fully involved heat release rate, might locally reach 1 1 35°C (from Equation 9.2.4.3, with K = 1 ) ,
100,000 kW, divided by the combined area of the two racks plus far in excess of the threshold for steel damage.
the aisle, ot· (9.75) (1.2) (2.2) + (9.75) (2.4) = 46.8 m2. Accord­
D.7 Sizing of Vents. This building arrangement will not meet
ingly, the heat release rate per unit area is
design objectives. However, it might be instructive to investigate
the venting requirements in order to illustrate general proce­
[D.6a] dures that might be used to develop alternative designs.
" 100,000 All 16 vents are predicted to be open prior to 566 seconds ­
Q = 2136 kW/m 2
46.8 d1e time of interest.

This value can be assumed to be representative of most of The aerodynamic vent at·ea, A,.,, is determined with the aid
the fire histoty, except for the initial stage. The effective diame­ of Equation 9.2.4.1:
ter of the fire at 100,000 kW is then, using Equation 8.3.7,

[ ]
[D.6b]
'1 2
4(1 00,000)
D= = 7.72 m
n(2136) Rack 1 1 .2 m

Equation 9.2.4.3 is used to estimate the smoke layer tempera­

ture rise. The mass flow rate in the plume as it enters the
fire diameter
T2.4 m
smoke layer, m/1 , is calculated from Equation 9.2.3.6 or 9.2.3.7,

..------>.d---1-.L--� _l_
depending on whether the flame height is smaller or larger
than the height of the smoke layer above the base of the fire,
3-0.5 = 2.5 m. The flame height is calculated from Equation 1 .2 m
9.2.3, as follows: Rack 2

[D.6c]
------- 9.75 m --------....! �
[
L = [- 1.02(7.72)] + 0.235(100,000)21 5 J = 15.6 m FIGURE D.6 Effective Fire Diameter.

2021 Edition
 ANNEX D 204-59

The nearest commercial vent size equal to or larger than this

( )
[D.7a]
1
( .,.) 1/ 2 7:t:J.T / 2 ,A. d1 / 2
m" = 2 P.2 ,
unit vent area would be selected.
, The following equation is used to check for O;easibk:
T2
At equilibrium, the mass flow thmugh the vents is equal to [D.7h]
the smoke production rate, m" . Substituting m" = 62.6 l<g/sec )
for 1n, in Equation 9.2.4. 1 , together with Qfto"""' = 23,200 (H - d 5/ 2

p. = 1.2 kg/m3 Qfiosi&b = 229,265 kW = 230 MW

g = 9.81 m/sec2 where:
T, = 294 K Q;,.,;ble = feasible fire heat release rate (kW)
· H = 9.1 - 0.5 = 8.6 m
/:o,.T= 559 K d = 6.1 m
T= 294 + 559 = 853 K This value is higher than the projected heat release rate, 100
d= 9.1-3 = 6. l m MW, and by itself is not of direct concern.

the equation can be solved for the aemdynamic vent area. D.8 Increased Height of Smoke Interface. Inspection of
The result is Equation 9.2.3.7 indicates that the larger the height of the
smoke interface above the base of the fire, the larger the value
[D. 7b]
of mass entrained in the plume, 1h1, , and Equation 9.2.4.3 indi­
cates that the temperature rise in the smoke layer will be
reduced. The calculations just completed for a smoke layer
height of 3 m above the floor can be repeated for other smoke
The vents are assumed to have a discharge coefficient of layer heights in search of acceptable alternative designs. The
0.61; therefore, the cot-responding actual vent area is (see two additional smoke layer heights of 6 m and 7.3 m have been
A. 9.2.4.2) investigated, d1e latter near the maximum associated with the
minimum recommended curtain depth for the 9.1 m high
[D.7c] building (see Section 7.3). The final result� of these additional
calculations indicate values of temperature rise in the smoke
10 04 layer of 253 K for the 6 m high level and 205 K for the 7.3 m
Au = · = 16.46 m2 (geomeu·ic vent area) = 16.5 m2
0.61 high level. Although these values for smoke layer temperature
rise are still a little high compared to the target of 164 K, they
The building design contemplates that inlet air openings will represent a major improvement. Furthermore, the tempera­
be 1.5 times the vent area. Equation F.2 is used to calculate a tures are low enough so as not to represent a flashover hazard
correction, M, for the limited inlet air openings. or endanger structural steel.
The calculations for the three smoke layer heights at the
[D.7d] maximum heat release rate are summat·ized in Table D.S,
entered as cases 1-3. In the table, H, represents the height of
the ceiling above the floor, Hr - d is the height of the smoke
interface above the floor, and H - d is the height of the smoke
interface above the base of the fire. In cases 1-3, the radiant
heat flux at floor level, jlux11, is seen to decrease to 5.1 kW/m2
and 3.5 kW/m2 as the smoke interface is raised but still
[ (-1)( 294 )]1 1 2 = l.07
[D.7e]
remains above 2.5 kW/m2 . The total required vent area
M = 1 + (corrected A,) increases sharply as the smoke layer interface is
1.52 853 raised. For the largest interface height, the total vent area of
89.2 m2 corresponds to an area per vent of 89.2/ 16 = 5.57 m2,
The corrected actual vent area is which is still smaller than the maximum vent area discussed in
5.4.1 [(i.e., 2d2 = 2(1.8) 2 = 6.48 m2] .
[D.7f] D.9 Growing Fire. Cases 4-6 in Table D.8 correspond to the
(1.07)(16.5) = 17.66 m2 growing fire with detection at 230 seconds using heat detectors.
The state of the fire is represented at a time 300 seconds follow­
Distributed among the 16 vent locations, the actual area per ing detection with heat detectors (i.e., at 230 + 300 =
vent is 530 seconds). It is assumed that all 16 vent� are operated
together at the alarm of the first heat detector; alternatively,
the vents are actuated individually with fusible links of the same
[D.7g] Rfl and activation temperature as the heat detectors, for which
--
17.66 it might be confit·med with DETACT-QS that all vents open
- 1 . 10 m2 prior to 530 seconds. The calculations are parallel to cases 1-3,
16 except that d1e fire is slightly smaller, as determined from the
following:

2021 Edition
204-60 SMOKE AND HEAT VENTLNG

Table D.8 Results of Calculations for Vent Design

Time Q D L H. - d H-d d D.. T fluxl

f
mp (kg/ corr. Av
Case (sec) (MW) (m) (m) (m) (m) (m) (K) (kW/m2 ) sec) M (m2)

1 �566 100.0 7.7 15.6 3.0 2.5 6.1 557 29.7 62.8 1.07 17.6
2 �566 100.0 7.7 15.6 6.0 5.5 3.1 253 5.1 137.8 1.11 53.8
3 �566 100.0 7.7 15.6 7.3 6.8 1.8 205 3.5 170.4 1.12 89.2
4 530 86.8 7.2 14.9 3.0 2.5 6.1 531 26.4 57.2 1.08 16.1
5 530 86.8 7.2 14.9 6.0 5.5 3.1 241 4.7 125.9 1.12 49.7
6 530 86.8 7.2 14.9 7.3 6.8 1.8 195 3.3 155.7 1.13 82.6
7 348 34.4 4.5 10.7 3.0 2.5 6.1 383 1 1 .8 31.4 1.09 8.6
8 348 34.4 4.5 10.7 6.0 5.5 3.1 174 2.7 69.0 1.13 28.3
9 348 34.4 4.5 10.7 7.3 6.8 1.8 141 2.0 85.3 1.14 47.8

The values for this fire will be used as input for LAVENT
[D.9a] The fire is assumed to start in the center of the building.
Q = 0.36(t - 39) 2 = 0.36(530 -39l = 86,800 kW A complete smoke detection system is to be installed with
detectors spaced 9.1 m on center. Detectors are located a maxi­
In cases 4-6, the smoke layer temperatures (�7) and radiant mum of 6.5 m from the fire axis (i.e., one-half the diagonal
fluxes to the floot- are only slightly reduced fi-om the con·e­ distance between detectors). As noted in A9.2.5.4.4. 1 , detec­
sponding steady fire situations, cases 1-3. Also, there is little tors have an activation temperature of 31 °C ( l 0°C above ambi­
change in the required vent areas. ent) and are located 0.1 m below the ceiling.
Cases 7-9 in Table D.8 correspond to the gmwing fire, with The vent design will use sixteen 1.76 m2 vents located 18.3 m
detection at 48 seconds using smoke detectors. Again, the state on center. All vents automatically open on activation of the first
of the fire is represented at a time 300 seconds from detection smoke detector.
(i.e., at 348 seconds). It is assumed that the 16 vents are oper­
ated together at the alarm of the first smoke detector. The LAVENT predicts that the upper-layer temperature will be
calculations are executed at a state of fire development as 377°C and that the upper "hot" layer will be 4.6 m above floor
follows: level at 600 seconds. A 3 m clear layer is maintained through­
out the 600 second time interval. However, heat flux at floor
level is projected to be appmximately 10 kW/m 2 at
[D.9b] 600 seconds, and the design objective of limiting heat flux to
Q = 0.36(t - 39) 2 = 0.36(348 - 39) 2 = 34,400 kW 2.5 kW/m2 at floor level is exceeded. At 342 seconds, tl1e time
of detection plus 300 seconds, however, the design objectives
are met. At 360 seconds, LAVENT predicts the upper-layer
It is seen that case 9 meets the design objective of heat fluxes temperature as 444 K (171 o q , with the layer being 7.3 m above
to the floor that are calculated as being lower tlun 2.5 kW/m2 , the floor. The predicted 150 K temperature rise is limited to
and case 8 nearly does so. The required vent areas are 28.3 m2 less than the target value of 164 K. and heat flux at floor level is
and 47.8 m2 for cases 8 and 9, respectively, corresponding to predicted to be 2.2 kW/m 2. Therefore, the design objectives
unit vent areas (16 vents) of 1.8 m2 and 3.0 m2 , both of which are satisfied for a time interval greater than the time of detec­
are well below their t-espective maxima, 2d1, based on 5.4.1. tion plus 300 seconds.
It will be noted that the case 8 solution using "hand calcula­ Inlet air is 1.5 times the vent area. To maintain tl1e vent flow
tions" provides an approximation close to the LAVENT predic­ predicted by LAVENT, inlet air net free area should be main­
tions, which are summarized next. tained at a minimum of twice the open vent area. Although the
D.IO LAVENT Analysis. The case 8 vent design in Table D.8 net free inlet air area is less than required, the inlet area is
vvill now be analyzed using the computer program LAVENT sufficiently large that LAVENT predictions can be assumed to
[3]. LAVENT is able to assess the time-varying events associated be reasonably valid. However, considet·ation should be given to
with the predicted fire. The fire has been previously deter­ increasing the vent area to account for the restrictions in inlet
mined as follows: air.
See Figure D.10(a) through Figure D.10(h) for results of the
[D.IO] program, and Figure D.10(i) for a computer printout of tl1e
Q = 0.18t2for 0 < t :o; 134 sec L AVENT output.
Q = 0.36(t- 39) 2 for 134 < t :o; 566 sec
Q = 100,000 kW for t > 566 sec

2021 Edition
 ANNEX D 204-61

650 0 . 10E+09

0 . 90E+08
600

0 . 80E+08
550
0 . 70E+08
�
(1)
'"' 500 ; 0 . 60E+08
::l
.j.J .j.J
"'
'"'(1)
::l
0.
450 .j.J 0 . 50E+08
::l
it
(1)
0
.j.J (1)
'"' 0 . 40E+08
'"'(1) 400 ....rz..
>.
"' 0 . 30E+08
H

350

300

250
0 150 300 450 600
Time ( s e c ) Time ( se c )

FIGURE D.IO(a) Layer Temperature. FIGURE D.IO(c) Fire Output.

9.5 30

28
9.0
26

8.5 24

22
8.0
20
e
7.5 "'e 18
.j.J
.<::
t1> "' 16
..... 7.0 (1)
'"'
(1)
.<:: "' 14
'"' .j.J
0:
(1) 6 . 5 12
>. (1)
"' :>
H
10
6.0
8

5.5 6

4
5.0
2

0
0 150 300 450 600
Time ( s e c ) Time ( sec )

FIGURE D.IO(b) Layer Height. FIGURE D.IO(d) Vent Area.

2021 Edition
204-62 SMOKE AND HEAT VENTLNG

14,000 1050

13,00 0 1000

950
12,000
900
11,000
850
10,000
� 800
9,000 til
0' .. 750
.»<: "
....,
8,000 Ill 700
"' ..
"'
Ill til0.
7,000
6 6 650
..
til
....,
til 6,000 600
>.
Ill
..
0
H 5,000 ....,
0
550
til 500
....,
4,000 til
c 450
3,000
400
2,000
350

300

250
0 150 300 450 600
Time ( sec) Time ( s e c )

FIGURE D.IO(e) Layer Mass. FIGURE D.IO(g) Detector Temperature.

120 1050

1000
110
950
100
900

90 850

0 800
til
"'
80 :.:
..... 750
0'
.»<:
til
70 ..
" 700
....,
;3:
0
Ill
60 ..
.-<
....
til 650
0.
til 50
6til 600
6" ....,
.-< ....,
550
P< 40 til
,.., 500

30 450

400
20
350
10
300

250
0 150 300 450 600
Time ( s e c ) Time ( sec)

FIGURE D.IO(f) Plume Flow. FIGURE D.IO(h) Jet Temperature.

2021 Edition
 ANNEX D 204-63

CEILING !!EIGHT 9.1 M

ROOM LENGTH = 73.0 M
ROOM WIDTH = 73.0 M
CURTAIN LENGTH 292.0 M
CURTAIN HEIGHT 0. 0 M
MATERIAL = INSULATED DECK (SOLID POLYSTYRENE)
CEILING CONDUCTIVITY . 149E+00 W/M K
CEILING DENSITY = . 1 16E+04 KG/M3
CEILING HEAT CAPACITY . 1 05E+04 J/M K
CEILING THICKNESS . 152E+OO M
FIRE HEIGHT = 0.5 M
FIRE POWER/AREA 0 . 2136E+07 W/M2

LINK NO = RADIUS 6.5 M DIST CEILING = 0.1 M

RTI = 1 . 0 0 SQRT (MS) FUSION TEMPERATURE FOR LINK 304 . 00 VENT
VENT AREA 2 8 . 2 M2 LINK CONTROLLING VENT

TIME ( S ) = 0 . 00 0 0 LYR TEMP (K)= 2 9 4 . 0 LYR HT (M) = 9 . 10

LYR MASS (KG)=O. OOOE+OO FIRE OUTPUT (W) = O . O OOOE+OO VENT AREA (M2) = 0.00
LINK = 1 LINK TEMP (K) = 2 9 4 . 0 0 JET VELOCITY (M/S) = 0 . 0 0 0 JET TE�W (K) = 294 . 0
R (M) 0 . 0 0 TSL (K) 2 9 4 . 0 QB (W/M2) O . OOOE+OO QT (W/M2) O . OOOE+OO
R (M) 1 . 74 TSL (K) 2 9 4 . 0 QB (W/M2) O . OOOE+OO QT (W/M2) O . OOOE+OO
R (M) 3 . 4 8 TSL (K) 2 9 4 . 0 QB (W/M2) O . OOOE+OO QT (W/M2) O . OOOE+OO
R (M) 5 . 22 TSL (K) 2 9 4 . 0 QB (W/M2) O . OOOE+OO QT (W/M2) O . OOOE+OO
R (M) 6 . 9 5 TSL (K) 2 9 4 . 0 QB (W/M2) O . OOOE+OO QT (W/M2) O . OOOE+OO
R (M) 8 . 6 9 TSL (K) 2 9 4 . 0 QB (W/M2) O . OOOE+OO QT (W/M2) O . OOOE+OO
R (M) 1 0 . 4 3 TSL (K) 2 9 4 . 0 QB (W/M2) O . OOOE+OO QT (W/M2) O . OOOE+OO
R (M) 12 . 1 7 TSL ( K) 2 9 4 . 0 QB (W/M2) O . OOOE+OO QT (W/M2) O . OOOE+OO
R (M) 13 • 91 TSL ( K) 2 9 4 . 0 QB (W/M2) O . OOOE+OO QT (W/M2) O . OOOE+OO
R (M) 15 . 6 5 TSL ( K) 2 9 4 . 0 QB (W/M2) O . OOOE+OO QT (W/M2) O . OOOE+OO
R (M) 1 7 . 39 TSL (K) 2 9 4 . 0 QB (W/M2) O . O OOE+OO QT (W/M2) O . OOOE+OO
R (M) 19 . 12 TSL (K) 2 9 4 . 0 QB (W/M2) O . O OOE+OO QT (W/M2) O . OOOE+OO
R (M) 2 0 . 86 TSL (K) 2 9 4 . 0 QB (W/M2) O . O OOE+OO QT (W/M2) O . OOOE+OO
R (M) 22 . 6 0 TSL ( K) 2 9 4 . 0 QB (W/M2) O . O OOE+OO QT (W/M2) O . OOOE+OO
R (M) 24 . 3 4 TSL ( K) 2 9 4 . 0 QB (W/M2) O . O OOE+OO QT (W/M2) O . OOOE+OO
R (M) 2 6 . 0 8 TSL (K) 2 9 4 . 0 QB (W/M2) O . O OOE+OO QT (W/M2) O . OOOE+OO
R (M) 2 7 . 82 TSL (K) 2 9 4 . 0 QB (W/M2) O . O OOE+OO QT (W/M2) O . OOOE+OO
R (M) 29 . 5 6 TSL ( K) 2 9 4 . 0 QB (W/M2) O . O OOE+OO QT (W/M2) O . OOOE+OO
R (M) 3 1 . 2 9 TSL (K) 2 9 4 . 0 QB (W/M2) O . O OOE+OO QT (W/M2) O . OOOE+OO
R (M) 33 . 0 3 TSL ( K) 2 9 4 . 0 QB (W/M2) O . O O OE+OO QT (W/M2) O . OOOE+OO
R (M) 34 . 7 7 TSL ( K) 2 9 4 . 0 QB (W/M2) O . O O OE+OO QT (W/M2) O . OOOE+OO
R (M) 36 . 51 TSL ( K) 2 9 4 . 0 QB (W/M2) O . O O OE+OO QT (W/M2) O . OOOE+OO
R (M) 3 8 . 2 5 TSL (K) 2 9 4 . 0 QB (W/M2) O . O O OE+OO QT (W/M2) O . OOOE+OO
R (M) 39 . 9 9 TSL (K) 2 9 4 . 0 QB (W/M2) O . O O OE+OO QT (W/M2) O . OOOE+OO
R (M) 4 1 . 7 3 TSL (K) 2 9 4 . 0 QB (W/M2) O . O O OE+OO QT (W/M2) O . OOOE+OO
R (M) 43 . 4 6 TSL (K) 2 9 4 . 0 QB (W/M2) O . O O OE+OO QT (W/M2) O . OOOE+OO
R (M) 45 . 2 0 TSL (K) 2 9 4 . 0 QB (W/M2) O . O O OE+OO QT (W/M2) O . OOOE+OO
R (M) 46 . 9 4 TSL (K) 2 9 4 . 0 QB (W/M2) O . O O OE+OO QT (W/M2) O . OOOE+OO
R (M) 4 8 . 6 8 TSL (K) 2 9 4 . 0 QB (W/M2) O . OOOE+OO QT (W/M2) O . OOOE+OO
R (M) 5 0 . 4 2 TSL (K) 2 9 4 . 0 QB (W/M2) O . OOOE+OO QT (W/M2) O . OOOE+OO

TIME ( S ) = 6 0 . 0 0 0 0 LYR TEMP (K)= 3 0 1 . 4 LYR HT (M) = 8 . 99

LYR MASS (KG)=0. 657E+03 FIRE OUTPUT (W) = 0 . 64 8 0E+06 VENT AREA (M2) 28.20
LINK = 1 LINK TEMP (K) 3 0 9 . 9 5 JET VELOCITY (M/S) = 1 . 104
JET TEMP (K) = 310.2 TIME LINK 1 OPENS EQUALS 4 1 . 7 0 9 8 (S)
R (M) 0 . 0 0 TSL (K) 3 0 2 . 1 QB (W/M2) 0 . 834E+03 QT (W/M2) O . OOOE+OO
R (M) 1 . 74 TSL (K) 2 9 9 . 5 QB (W/M2) 0 . 5 87E+03 QT (W/M2) O . OOOE+OO
R (M) 3 . 4 8 TSL (K) 2 9 7 . 8 QB (W/M2) 0 . 4 17E+03 QT (W/M2) O . OOOE+OO
R (M) 5 . 22 TSL (K) 2 9 6 . 6 QB (W/M2) 0 . 2 87E+03 QT (W/M2) O . OOOE+OO
R (M) 6 . 9 5 TSL (K) 2 9 5 . 8 QB (W/M2) 0 . 205E+03 QT (W/M2) O . OOOE+OO
R (M) 8 . 6 9 TSL (K) 2 9 5 . 4 QB (W/M2) 0 . 153E+03 QT (W/M2) O . OOOE+OO
R (M) 1 0 . 4 3 TSL (K) 2 9 5 . 0 QB (W/M2) 0 . 1 17E+03 QT (W/M2) O . OOOE+OO
R (M) 12 . 1 7 TSL ( K) 2 9 4 . 8 QB (W/M2) 0 . 925E+02 QT (W/M2) O . OOOE+OO
R (M) 13 • 9 1 TSL ( K) 2 9 4 . 7 QB (W/M2) 0 . 74BE+02 QT (W/M2) O . OOOE+OO

FIGURE D.IO(i) LAVENT Analysis Output.

2021 Edition
204-64 SMOKE AND HEAT VENTLNG

R (M) 1 5 . 65 TSL ( K ) 294 . 6 QB (W/M2) 0 . 6 1 9E+02 QT (W/M2) O . OO OE+OO

R (M) 1 7 . 39 TSL ( K ) 294 . 5 QB (W/M2) 0 . 522E+02 QT (W/M2) O . OO OE+OO
R (M) 1 9 . 12 TSL ( K ) 294 . 4 QB (W/M2) 0 . 448E+02 QT (W/M2) O . OO OE+OO
R (M) 2 0 . 86 TSL ( K ) 294 . 3 QB (W/M2) 0 . 389E+02 QT (W/M2) O . O OOE+OO
R (M) 2 2 . 6 0 TSL ( K ) 294 . 3 QB (W/M2) 0 . 343E+02 QT (W/M2) O . O OOE+OO
R (M) 2 4 . 3 4 TSL ( K ) 294 . 3 QB (W/M2) 0 . 305E+02 QT (W/M2) O . O OOE+OO
R (M) 2 6 . 08 TSL ( K ) 294 . 2 QB (W/M2) 0 . 2 74E+02 QT (W/M2) O . O OOE+OO
R (M) 2 7 . 82 TSL ( K ) 294 . 2 QB (W/M2) 0 . 248E+02 QT (W/M2) O . O OOE+OO
R (M) 2 9 . 56 TSL ( K ) 294 . 2 QB (W/M2) 0 . 226E+02 QT (W/M2) O . O OOE+OO
R (M) 3 1 . 29 TSL ( K ) 294 . 2 QB (W/M2) 0 . 20 7E+02 QT (W/M2) O . O OOE+OO
R (M) 3 3 . 03 TSL ( K ) 294 . 2 QB (W/M2) 0 . 1 9 1E+02 QT (W/M2) O . O OOE+OO
R (M) 3 4 . 77 TSL ( K) 294 . 2 QB (W/M2) 0 . 1 77E+02 QT (W/M2) O . O OOE+OO
R (M) 3 6 . 51 TSL (K) 294 . 1 QB (W/M2) 0 . 165E+02 QT (W/M2) O . OOOE+OO
R (M) 3 8 . 25 TSL (K) 294 . 1 QB (W/M2) 0 . 154E+02 QT (W/M2) O . OOOE+OO
R (M) 3 9 . 99 TSL (K) 294 . 1 QB (W/M2) 0 . 144E+02 QT (W/M2) O . OOOE+OO
R (M) 4 1 . 73 TSL (K) 294 . 1 QB (W/M2) 0 . 136E+02 QT (W/M2) O . OOOE+OO
R (M) 4 3 . 46 TSL (K) 294 . 1 QB (W/M2) 0 . 128E+02 QT (W/M2) O . OOOE+OO
R (M) 4 5 . 20 TSL (K) 294 . 1 QB (W/M2) 0 . 121E+02 QT (W/M2) O . OOOE+OO
R (M) 4 6 . 94 TSL (K) 294 . 1 QB (W/M2) 0 . 115E+02 QT (W/M2) O . OOOE+OO
R (M) 4 8 . 68 TSL (K) 294 . 0 QB (W/M2) 0 . 122E+01 QT (W/M2) O . OOOE+OO
R (M) 5 0 . 42 TSL (K) 294 . 0 QB (W/M2) 0 . 1 10E+01 QT (W/M2) O . OOOE+OO

TIME ( S ) = 120 . 00 0 0 LYR TEMP (K)= 3 1 7 . 2 LYR HT (M) = 8 . 83

LYR MASS (KG ) =0 . 162E+04 FIRE OUTPUT (W) = 0 . 2743E+07 VENT AREA ( M2 ) 28.20
LINK = 1 LINK TEMP (K) 3 3 9 . 8 3 JET VELOCITY (M/S) = 1 . 76 1
JET TEMP (K) = 340 . 2 TIME LINK 1 OPENS EQUALS 4 1 . 7098 (S)
R (M) 0 . 0 0 TSL ( K ) 332 . 0 Q B (W/M2) 0 . 242E+04 Q T (W/M2) O . OOOE+OO
R (M) 1 . 74 TSL ( K ) 3 2 2 . 4 QB (W/M2) 0 . 1 8 8E+04 QT (W/M2) O . OOOE+OO
R (M) 3 . 48 TSL ( K ) 314 . 9 QB (W/M2) 0 . 142E+04 QT (W/M2) O . OOOE+OO
R (M) 5 . 22 TSL ( K ) 30 8 . 8 QB (W/M2) 0 . 1 02E+04 QT (W/M2) O . OOOE+OO
R (M) 6 . 95 TSL ( K ) 304 . 7 QB (W/M2) 0 . 753E+03 QT (W/M2) O . OOOE+OO
R (M) 8 . 69 TSL ( K ) 302 . 1 QB (W/M2) 0 . 569E+03 QT (W/M2) O . OOOE+OO
R (M) 1 0 . 43 TSL ( K ) 30 0 . 2 QB (W/M2) 0 . 441E+03 QT (W/M2) O . OOOE+OO
R (M) 1 2 . 17 TSL ( K ) 298 . 9 QB (W/M2) 0 . 350E+03 QT (W/M2) O . OOOE+OO
R (M) 1 3 . 91 TSL ( K ) 298 . 0 QB (W/M2) 0 . 285E+03 QT (W/M2) O . OOOE+OO
R (M) 1 5 . 65 TSL ( K ) 29 7 . 3 QB (W/M2) 0 . 236E+03 QT (W/M2) O . OOOE+OO
R (M) 1 7 . 39 TSL ( K) 296 . 8 QB (W/M2) 0 . 199E+03 QT (W/M2) O . OOOE+OO
R (M) 1 9 . 12 TSL (K) 296 . 4 QB (W/M2) 0 . 1 71E+03 QT (W/M2) O . OOOE+OO
R (M) 2 0 . 86 TSL (K) 296 . 1 QB (W/M2) 0 . 149E+03 QT (W/M2) O . OOOE+OO
R (M) 2 2 . 6 0 TSL (K) 295 . 8 QB (W/M2) 0 . 13 1E+03 QT (W/M2) O . OOOE+OO
R (M) 2 4 . 34 TSL (K) 295 . 6 QB (W/M2) 0 . 1 17E+03 QT (W/M2) O . OOOE+OO
R (M) 2 6 . 0 8 TSL (K) 295 . 5 QB (W/M2) 0 . 105E+03 QT (W/M2) O . OOOE+OO
R (M) 2 7 . 82 TSL ( K) 295 . 3 QB (W/M2) 0 . 951E+02 QT (W/M2) O . OOOE+OO
R (M) 2 9 . 56 TSL (K) 295 . 2 QB (W/M2) 0 . 86 7E+02 QT (W/M2) O . OOOE+OO
R (M) 3 1 . 29 TSL (K) 295 . 1 QB (W/M2) 0. 795E+02 QT (W/M2) O . OOOE+OO
R (M) 3 3 . 03 TSL (K) 295 . 0 QB (W/M2) 0. 734E+02 QT (W/M2) O . OOOE+OO
R (M) 3 4 . 77 TSL (K) 294 . 9 QB (W/M2) 0 . 6 80E+02 QT (W/M2) O . OOOE+OO
R (M) 3 6 . 51 TSL (K) 294 . 9 QB (W/M2) 0 . 6 33E+02 QT (W/M2) O . OOOE+OO
R (M) 3 8 . 25 TSL (K) 294 . 8 QB (W/M2) 0 . 592E+02 QT (W/M2) O . OOOE+OO
R (M) 3 9 . 99 TSL (K) 294 . 8 QB (W/M2) 0 . 555E+02 QT (W/M2) O . OOOE+OO
R (M) 4 1 . 73 TSL (K) 294 . 7 QB (W/M2) 0 . 522E+02 QT (W/M2) O . OOOE+OO
R (M) 4 3 . 46 TSL (K) 294 . 7 QB (W/M2) 0 . 492E+02 QT (W/M2) O . OOOE+OO
R (M) 4 5 . 20 TSL (K) 294 . 6 QB (W/M2) 0 . 466E+02 QT (W/M2) O . OOOE+OO
R (M) 4 6 . 94 TSL (K) 294 . 6 QB (W/M2) 0 . 442E+02 QT (W/M2) O . OOOE+OO
R (M) 4 8 . 6 8 TSL (K) 294 . 1 QB (W/M2) 0 . 504E+01 QT (W/M2) O . OOOE+OO
R (M) 5 0 . 42 TSL (K) 294 . 1 QB (W/M2) 0 . 455E+01 QT (W/M2) O . OOOE+OO

TIME ( S ) = 1 8 0 . 0 0 0 0 LYR TEMP ( K ) = 3 39 . 8 LYR HT (M) = 8 . 60

LYR MASS (KG ) =0 . 276E+04 FIRE OUTPUT (W) = 0 . 7483E+07 VENT AREA ( M2 ) 28.20
LINK = 1 LINK TEMP ( K ) 3 8 5 . 7 3 JET VELOCITY (M/S) = 2 . 493
JET TEMP (K) = 386.3 TIME LINK 1 OPENS EQUALS 41.7098 (S)
R (M) 0 . 00 TSL ( K ) 386 . 4 Q B (W/M2) 0 . 5 14E+04 Q T (W/M2) O . OOOE+OO
R (M) 1 . 74 TSL ( K ) 36 7 . 0 Q B (W/M2) 0 . 4 2 1E+04 Q T (W/M2) O . OOOE+OO
R (M) 3 . 48 TSL ( K ) 34 9 . 7 Q B (W/M2) 0. 329E+04 Q T (W/M2) O . OOOE+OO

FIGURE D.IO(i) Continued

2021 Edition
 ANNEX D 204-65

R (M) 5 . 2 2 TSL (K) 3 3 4 . 5 QB (W/M2} 0 . 244E+04 QT (W/M2) O . O OOE+OO

R (M) 6 . 9 5 TSL (K) 324 . 0 QB (W/M2} 0 . 1 83E+04 QT (W/M2) O . O OOE+OO
R (M) 8 . 6 9 TSL (K) 3 1 6 . 7 QB (W/M2) 0 . 140E+04 QT (W/M2} O . O OOE+OO
R (M) 1 0 . 4 3 TSL (K) 3 1 1 . 6 QB (W/M2) 0 . 1 09E+04 QT (W/M2} O . O OOE+OO
R (M) 1 2 . 1 7 TSL (K) 3 0 8 . 0 QB (W/M2) 0 . 864E+03 QT (W/M2} O . O OOE+OO
R (M) 1 3 . 9 1 TSL (K) 3 0 5 . 3 QB (W/M2) 0 . 702E+03 QT (W/M2} O . O OOE+OO
R (M) 1 5 . 6 5 TSL (K) 3 0 3 . 4 QB (W/M2) 0 . 582E+03 QT (W/M2} O . O OOE+OO
R (M) 1 7 . 3 9 TSL ( K) 3 0 1 . 9 QB (W/M2) 0 . 4 9 1E+03 QT (W/M2) O . O OOE+OO
R (M) 1 9 . 12 TSL (K) 3 0 0 . 8 QB (W/M2) 0 . 420E+03 QT (W/M2) O . O OOE+OO
R (M) 2 0 . 8 6 TSL (K) 2 9 9 . 9 QB (W/M2) 0 . 365E+03 QT (W/M2) O . O OOE+OO
R (M) 2 2 . 6 0 TSL (K) 2 9 9 . 2 QB (W/M2) 0 . 3 2 1E+03 QT (W/M2) O . O OOE+OO
R (M) 24.34 TSL (K) 2 9 8 . 6 QB (W/M2) 0 . 2 8 6E+03 QT (W/M2) O . O OOE+OO
R (M) 2 6 . 0 8 TSL (K) 2 9 8 . 1 QB (W/M2) 0 . 2 5 6E+03 QT (W/M2} O . O OOE+OO
R (M) 2 7 . 82 TSL (K) 2 9 7 . 7 QB (W/M2) 0 . 2 32E+03 QT (W/M2} O . O OOE+OO
R (M) 2 9 . 5 6 TSL (K) 2 9 7 . 4 QB (W/M2) 0 . 2 1 1E+03 QT (W/M2} O . O OOE+OO
R (M) 31. 2 9 TSL ( K ) 2 9 7 . 1 QB (W/M2} 0 . 193E+03 QT (W/M2} O . O OOE+OO
R (M) 3 3 . 0 3 TSL (K) 2 9 6 . 9 QB (W/M2} 0 . 1 7 8E+03 QT (W/M2} O . O OOE+OO
R (M) 3 4 . 7 7 TSL (K) 2 9 6 . 7 QB (W/M2} 0 . 1 6 5E+03 QT (W/M2} O . O OOE+OO
R (M) 3 6 . 5 1 TSL (K) 2 9 6 . 5 QB (W/M2) 0 . 154E+03 QT (W/M2) O . O OOE+OO
R (M) 3 8 . 2 5 TSL (K) 2 9 6 . 3 QB (W/M2) 0 . 143E+03 QT (W/M2) O . O OOE+OO
R (M) 3 9 . 99 TSL (K) 2 9 6 . 2 QB (W/M2} 0 . 134E+03 QT (W/M2) O . O OOE+OO
R (M) 4 1 . 73 TSL (K) 2 9 6 . 0 QB (W/M2} 0 . 126E+03 QT (W/M2) O . O OOE+OO
R (M) 4 3 . 4 6 TSL (K) 2 9 5 . 9 QB (W/M2} 0 . 1 19E+03 QT (W/M2) O . O OOE+OO
R (M) 4 5 . 2 0 TSL (K) 2 9 5 . 8 QB (W/M2) 0 . 1 13E+03 QT (W/M2} O . O OOE+OO
R (M) 4 6 . 9 4 TSL (K) 2 9 5 . 7 QB (W/M2) 0 . 1 07E+03 QT (W/M2} O . O OOE+OO
R (M) 4 8 . 6 8 TSL (K) 2 9 4 . 2 QB (W/M2) 0 . 136E+02 QT (W/M2} O . O OOE+OO
R (M) 5 0 . 4 2 TSL (K) 2 9 4 . 2 QB (W/M2} 0 . 123E+02 QT (W/M2} O . O OOE+OO

TIME ( S } = 2 4 0 . 0 0 0 0 LYR TEMP ( K } = 3 7 1 . 5 LYR H T (M} = 8.28

LYR MASS ( K G } = 0 . 4 14E+04 FIRE OUTPUT (W} = 0 . 1 541E+08 VENT AREA (M2) 28.20
LINK = 1 LINK TEMP ( K } 4 4 7 . 5 7 JET VELOCITY (M/S) = 3.186
JET TEMP ( K } = 448.2 TIME LINK 1 OPENS EQUALS 41.7098 (S)
R (M} 0 . 0 0 TSL (K} 4 6 9 . 7 QB (W/M2} 0 . 8 16E+04 QT (W/M2} O . O OOE+OO
R (M} 1 . 74 TSL (K} 4 3 9 . 3 QB (W/M2} 0 . 7 00E+04 QT (W/M2} O . O OOE+OO
R (M) 3 . 4 8 TSL (K} 4 0 8 . 8 QB (W/M2} 0 . 5 70E+04 QT (W/M2} O . O OOE+OO
R (M) 5.22 TSL (K} 3 8 0 . 2 QB (W/M2} 0 . 439E+04 QT (W/M2} O . O OOE+OO
R (M) 6 . 9 5 TSL (K} 3 5 9 . 0 QB (W/M2} 0 . 335E+04 QT (W/M2) O . O OOE+OO
R (M) 8 . 69 TSL (K} 3 4 3 . 8 QB (W/M2} 0 . 259E+04 QT (W/M2) O . O OOE+OO
R (M) 1 0 . 4 3 TSL (K} 332 . 8 QB (W/M2} 0 . 2 0 3E+04 QT (W/M2) O . O OOE+OO
R (M) 1 2 . 1 7 TSL (K) 324 . 9 QB (W/M2) 0 . 162E+04 QT (W/M2) O . O OOE+OO
R (M) 1 3 . 9 1 TSL (K) 3 1 9 . 1 QB (W/M2) 0 . 132E+04 QT (W/M2) O . O OOE+OO
R (M) 1 5 . 6 5 TSL (K) 3 1 4 . 8 QB (W/M2) 0 . 1 09E+04 QT (W/M2) O . O OOE+OO
R (M) 1 7 . 39 TSL (K} 3 1 1 . 6 QB (W/M2} 0 . 9 22E+03 QT (W/M2) O . O OOE+OO
R (M) 1 9 . 12 TSL (K} 3 0 9 . 1 QB (W/M2} 0 . 7 90E+03 QT (W/M2) O . O OOE+OO
R (M} 2 0 . 8 6 TSL (K} 3 0 7 . 1 QB (W/M2} 0 . 6 87E+03 QT (W/M2) O . O OOE+OO
R (M} 2 2 . 6 0 TSL (K} 3 0 5 . 5 QB (W/M2} 0 . 604E+03 QT (W/M2) O . O OOE+OO
R (M} 24.34 TSL (K} 3 0 4 . 2 QB (W/M2} 0 . 536E+03 QT (W/M2) O . O OOE+OO
R (M) 2 6 . 0 8 TSL (K} 3 0 3 . 2 QB (W/M2} 0 . 4 8 1E+03 QT (W/M2} O . O OOE+OO
R (M) 2 7 . 82 TSL (K} 3 0 2 . 3 QB (W/M2} 0 . 435E+03 QT (W/M2} O . O OOE+OO
R (M) 2 9 . 5 6 TSL (K} 3 0 1 . 6 QB (W/M2} 0 . 396E+03 QT (W/M2} O . O OOE+OO
R (M} 3 1 . 2 9 TSL (K} 3 0 0 . 9 QB (W/M2) 0 . 363E+03 QT (W/M2) O . O OOE+OO
R (M} 3 3 . 03 TSL (K} 3 0 0 . 4 QB (W/M2) 0 . 334E+03 QT (W/M2) O . O OOE+OO
R (M} 3 4 . 7 7 TSL (K} 2 9 9 . 9 QB (W/M2) 0 . 3 09E+03 QT (W/M2) O . O OOE+OO
R (M} 3 6 . 5 1 TSL (K} 2 9 9 . 5 QB (W/M2) 0 . 2 8 8E+03 QT (W/M2) O . O OOE+OO
R (M} 3 8 . 2 5 TSL (K} 2 9 9 . 1 QB (W/M2) 0 . 2 6 9E+03 QT (W/M2) O . O OOE+OO
R (M} 3 9 . 9 9 TSL (K} 2 9 8 . 8 QB (W/M2) 0 . 2 52E+03 QT (W/M2} O . O OOE+OO
R (M} 4 1 . 7 3 TSL (K} 2 9 8 . 5 QB (W/M2) 0 . 2 3 7E+03 QT (W/M2} O . O OOE+OO
R (M} 4 3 . 4 6 TSL (K} 2 9 8 . 3 QB (W/M2) 0 . 223E+03 QT (W/M2} O . O OOE+OO
R (M} 4 5 . 2 0 TSL (K} 2 9 8 . 0 QB (W/M2) 0 . 2 11E+03 QT (W/M2) O . O OOE+OO
R (M} 4 6 . 9 4 TSL (K} 2 9 7 . 8 QB (W/M2) 0 . 2 00E+03 QT (W/M2) O . O OOE+OO
R (M) 4 8 . 68 TSL (K) 2 9 6 . 6 QB (W/M2) 0 . 1 98E+03 QT (W/M2) O . O OOE+OO
R (M) 5 0 . 4 2 TSL (K) 2 9 4 . 5 QB (W/M2) 0 . 2 5 0E+02 QT (W/M2) O . O OOE+OO

FIGURE D.IO(i) Continued

2021 Edition
204-66 SMOKE AND HEAT VENTLNG

TIME ( S ) = 3 0 0 . 0 0 0 0 LYR TEMP ( K ) = 4 0 6 . 7 LYR HT (M) = 7 . 86

LYR MASS ( KG ) = 0 . 5 75E+04 FIRE OUTPUT (W) = 0 . 2 4 52E+08 VENT AREA (M2) 28.20
LINK = 1 LINK TEMP ( K ) 5 1 1 . 8 5 JET VELOCITY (M/S) = 3 . 6 99
JET TEMP (K) = 512.4 TIME LINK 1 OPENS EQUALS 41.7098 (S)
R (M) 0 . 0 0 TSL (K) 5 6 1 . 4 QB (W/M2) 0 . 962E+04 QT (W/M2) - 0 . 2 9 7E-11
R (M) 1 . 74 TSL (K) 5 2 3 . 2 QB (W/M2) 0 . 859E+04 QT (W/M2) - 0 . 297E-ll
R (M) 3 . 4 8 TSL (K) 4 8 1 . 7 QB (W/M2) 0 . 7 31E+04 QT (W/M2) -0. 297E-ll
R (M) = 5 . 2 2 TSL (K) 4 39 . 7 QB (W/M2) 0 . 5 88E+04 QT (W/M2) = - 0 . 2 9 7E-11
R (M) = 6 . 9 5 TSL (K) 4 0 6 . 1 QB (W/M2) 0 . 4 6 4E+04 QT (W/M2) = - 0 . 2 9 7E-11
R (M) = 8 . 6 9 TSL (K) 3 8 1 . 0 QB (W/M2) 0 . 365E+04 QT (W/M2) = - 0 . 2 9 7E-11
R (M) 1 0 . 4 3 TSL (K) 3 6 2 . 4 QB (W/M2) 0 . 289E+04 QT (W/M2) -0 .297E-11
R (M) 1 2 . 1 7 TSL (K) 3 4 8 . 8 QB (W/M2) 0 . 234E+04 QT (W/M2) -0 .297E-11
R (M) 1 3 . 9 1 TSL (K) 3 3 8 . 7 QB (W/M2) 0 . 1 91E+04 QT (W/M2) -0. 297E-ll
R (M) 1 5 . 6 5 TSL (K) 3 3 1 . 1 QB (W/M2) 0 . 1 5 9E+04 QT (W/M2) -0. 297E-ll
R (M) 1 7 . 3 9 TSL (K) 3 2 5 . 4 QB (W/M2) 0 . 135E+04 QT (W/M2) -0. 297E-ll
R (M) 1 9 . 12 TSL (K) 3 2 0 . 9 QB (W/M2) 0 . 1 16E+04 QT (W/M2) -0. 297E-11
R (M) 2 0 . 8 6 TSL (K) 3 1 7 . 4 QB (W/M2) 0 . 1 01E+04 QT (W/M2) -0. 297E-11
R (M) 2 2 . 6 0 TSL (K) 3 1 4 . 6 QB (W/M2) 0 . 8 87E+03 QT (W/M2) -0. 297E-11
R (M) 24.34 TSL (K) 3 1 2 . 3 QB (W/M2) 0 . 7 89E+03 QT (W/M2) -0. 297E-ll
R (M) 2 6 . 0 8 TSL (K) 3 1 0 . 4 QB (W/M2) 0 . 7 08E+03 QT (W/M2) -0. 297E-ll
R (M) 2 7 . 82 TSL (K) 3 0 8 . 8 QB (W/M2) 0 . 640E+03 QT (W/M2) -0. 297E-ll
R (M) 2 9 . 5 6 TSL (K) 3 0 7 . 5 QB (W/M2) 0 . 5 8 3E+03 QT (W/M2) -0. 297E-ll
R (M) 3 1 . 2 9 TSL (K) 3 0 6 . 4 QB (W/M2) 0 . 535E+03 QT (W/M2) -0. 297E-ll
R (M) 3 3 . 03 TSL (K) 3 0 5 . 4 QB (W/M2) 0 . 493E+03 QT (W/M2) -0. 297E-11
R (M) 3 4 . 7 7 TSL (K) 3 0 4 . 6 QB (W/M2) 0 . 456E+03 QT (W/M2) -0. 297E-11
R (M) 3 6 . 5 1 TSL (K) 3 0 3 . 8 QB (W/M2) 0 . 425E+03 QT (W/M2) -0. 297E-11
R (M) 3 8 . 2 5 TSL (K) 3 0 3 . 2 QB (W/M2) 0 . 3 9 7E+03 QT (W/M2) -0. 297E-ll
R (M) 3 9 . 9 9 TSL (K) 3 0 2 . 6 QB (W/M2) 0 . 3 72E+03 QT (W/M2) -0. 297E-ll
R (M) 4 1 . 73 TSL (K) 3 0 2 . 1 QB (W/M2) 0 . 3 5 0E+03 QT (W/M2) -0. 297E-ll
R (M) 4 3 . 4 6 TSL (K) 3 0 1 . 6 QB (W/M2) 0 . 3 3 0E+03 QT (W/M2) -0. 297E-ll
R (M) 4 5 . 2 0 TSL (K) 3 0 1 . 2 QB (W/M2) 0 . 3 12E+03 QT (W/M2) -0. 297E-ll
R (M) 4 6 . 9 4 TSL (K) 3 0 0 . 8 QB (W/M2) 0 . 296E+03 QT (W/M2) -0. 297E-11
R (M) 4 8 . 6 8 TSL (K) 2 9 9 . 8 QB (W/M2) 0 . 2 8 6E+03 QT (W/M2) -0. 297E-11
R (M) 50.42 TSL (K) 2 9 4 . 9 QB (W/M2) 0 . 3 9 0E+02 QT (W/M2) -0. 297E-11

TIME (S)= 3 6 0 . 0 0 0 0 LYR TEMP (K)= 443 . 6 LYR HT (M) = 7.31

LYR MASS ( KG ) = 0 . 7 6 0E+04 FIRE OUTPUT (W) = 0 . 3 795E+08 VENT AREA (M2) 28.20
LINK = 1 LINK TEMP (K) 5 9 0 . 3 1 JET VELOCITY (M/S) = 4.317
JET TEMP (K) = 59 0 . 9 TIME LINK 1 OPENS EQUALS 4 1 . 7098 (S)
R (M) 0 . 0 0 TSL (K) 6 5 8 . 1 Q B (W/M2) 0 . 1 17E+05 QT (W/M2) - 0 . 2 97E-11
R (M) 1 . 74 TSL (K) 6 1 4 . 7 QB (W/M2) 0 . 1 07E+05 QT (W/M2) - 0 . 297E-ll
R (M) 3 . 4 8 TSL (K) 564 . 3 QB (W/M2) 0 . 9 3 9E+04 QT (W/M2) -0. 297E-ll
R (M) 5.22 TSL (K) 5 1 0 . 0 QB (W/M2) 0 . 7 80E+04 QT (W/M2) -0. 297E-ll
R (M) 6 . 9 5 TSL (K) 4 6 3 . 8 QB (W/M2) 0 . 631E+04 QT (W/M2) -0. 297E-ll
R (M) 8 . 6 9 TSL (K) 4 2 7 . 5 QB (W/M2) 0 . 5 05E+04 QT (W/M2) -0. 297E-ll
R (M) 1 0 . 4 3 TSL (K) 3 9 9 . 9 QB (W/M2) 0 . 4 0 5E+04 QT (W/M2) -0. 297E-ll
R (M) 1 2 . 1 7 TSL (K) 3 7 9 . 3 QB (W/M2) 0 . 3 2 9E+04 QT (W/M2) -0. 297E-ll
R (M) 1 3 . 9 1 TSL (K) 3 6 3 . 9 QB (W/M2) 0 . 2 7 1E+04 QT (W/M2) -0. 297E-11
R (M) 1 5 . 6 5 TSL (K) 3 5 2 . 2 QB (W/M2) 0 . 226E+04 QT (W/M2) -0. 297E-11
R (M) 1 7 . 3 9 TSL (K) 3 4 3 . 2 QB (W/M2) 0 . 192E+04 QT (W/M2) -0. 297E-11
R (M) 1 9 . 12 TSL (K) 3 3 6 . 2 QB (W/M2) 0 . 165E+04 QT (W/M2) -0. 297E-ll
R (M) 2 0 . 8 6 TSL (K) 3 3 0 . 7 QB (W/M2) 0 . 143E+04 QT (W/M2) -0. 297E-ll
R (M) 2 2 . 6 0 TSL (K) 3 2 6 . 3 QB (W/M2) 0 . 126E+04 QT (W/M2) -0 .297E-ll
R (M) 24.34 TSL (K) 322 . 7 QB (W/M2) 0 . 112E+04 QT (W/M2) -0 .297E-ll
R (M) 2 6 . 0 8 TSL (K) 3 1 9 . 8 QB (W/M2) 0 . 1 01E+04 QT (W/M2) -0 .297E-ll
R (M) 2 7 . 82 TSL (K) 3 1 7 . 3 QB (W/M2) 0 . 9 10E+03 QT (W/M2) -0. 297E-11
R (M) 2 9 . 5 6 TSL (K) 3 1 5 . 2 QB (W/M2) 0 . 8 2 8E+03 QT (W/M2) -0. 297E-11
R (M) 3 1 . 2 9 TSL (K) 3 1 3 . 4 QB (W/M2) 0 . 7 5 9E+03 QT (W/M2) -0. 297E-11
R (M) 3 3 . 03 TSL (K) 3 1 1 . 9 QB (W/M2) 0 . 699E+03 QT (W/M2) - 0 . 297E-ll
R (M) 3 4 . 7 7 TSL (K) 3 1 0 . 6 QB (W/M2) 0 . 647E+03 QT (W/M2) - 0 . 297E-ll
R (M) 3 6 . 5 1 TSL (K) 3 0 9 . 4 QB (W/M2) 0 . 602E+03 QT (W/M2) -0. 297E-ll
R (M) 3 8 . 2 5 TSL (K) 3 0 8 . 4 QB (W/M2) 0 . 562E+03 QT (W/M2) -0. 297E-ll
R (M) 3 9 . 9 9 TSL (K) 3 0 7 . 5 QB (W/M2) 0 . 527E+03 QT (W/M2) -0. 297E-ll
R (M) 4 1 . 7 3 TSL ( K ) 3 0 6 . 7 QB (W/M2) 0 . 495E+03 QT (W/M2) -0. 297E-11

FIGURE D.IO(i) Continued

2021 Edition
 ANNEX D 204-67

R (M) 4 3 . 4 6 TSL (K) 3 0 6 . 0 QB (W/M2) 0 . 467E+03 QT (W/M2) -0. 297E-11

R (M) 45 . 2 0 TSL (K) 3 0 5 . 3 QB (W/M2) 0 . 442E+03 QT (W/M2) - 0 . 297E-11
R (M) 4 6 . 9 4 TSL (K) 3 0 4 . 7 QB (W/M2) 0 . 4 19E+03 QT (W/M2) - 0 . 297E-11
R (M) 4 8 . 6 8 TSL (K) 3 0 3 . 7 QB (W/M2) 0 . 402E+03 QT (W/M2) - 0 . 297E-ll
R (M) 5 0 . 4 2 TSL (K) 2 9 5 . 4 QB (W/M2) 0 . 5 9 7E+02 QT (W/M2) - 0 . 297E-ll

TIME (S)� 420 . 0 0 0 0 LYR TEMP (K)� 4 8 3 . 7 LYR HT (M) = 6 . 66

LYR MASS (KG)=0. 949E+04 FIRE OUTPUT (W) � 0 . 5283E+08 VENT AREA (M2) 28.20
LINK � 1 LINK TEMP (K) 6 7 7 . 1 8 JET VELOCITY (M/S) � 4 . 879
JET TEMP (K) = 677.9 TIME LINK 1 OPENS EQUALS 41.7098 (S)
R (M) 0 . 0 0 TSL (K) 7 4 7 . 8 Q B (W/M2) 0 . 129E+05 QT (W/M2) - 0 . 2 9 7E-ll
R (M) 1 . 74 TSL (K) 7 0 1 . 8 QB (W/M2) 0 . 120E+05 QT (W/M2) - 0 . 2 9 7E-ll
R (M) 3 . 4 8 TSL (K) 6 4 6 . 0 QB (W/M2) 0 . 10 8E+05 QT (W/M2) - 0 . 2 9 7E-11
R (M) 5 . 22 TSL (K) 5 8 3 . 0 QB (W/M2) 0 . 920E+04 QT (W/M2) -0. 297E-11
R (M) 6 . 9 5 TSL (K) 5 2 6 . 3 QB (W/M2) 0 . 764E+04 QT (W/M2) - 0 . 297E-11
R (M) 8 . 69 TSL (K) 4 7 9 . 6 QB (W/M2) 0 . 625E+04 QT (W/M2) - 0 . 297E-11
R (M) 1 0 . 4 3 TSL (K) 4 4 3 . 0 QB (W/M2) 0 . 5 10E+04 QT (W/M2) - 0 . 297E-11
R (M) 12 . 1 7 TSL ( K) 4 1 4 . 9 QB (W/M2) 0 . 419E+04 QT (W/M2) - 0 . 297E-11
R (M) 13 . 91 TSL ( K) 3 9 3 . 6 QB (W/M2) 0 . 347E+04 QT (W/M2) - 0 . 297E-11
R (M) 1 5 . 6 5 TSL (K) 3 7 7 . 2 QB (W/M2) 0 . 292E+04 QT (W/M2) - 0 . 297E-11
R (M) 1 7 . 3 9 TSL ( K) 3 6 4 . 6 QB (W/M2) 0 . 249E+04 QT (W/M2) - 0 . 297E-11
R (M) 19 . 12 TSL (K) 3 5 4 . 7 QB (W/M2) 0 . 214E+04 QT (W/M2) - 0 . 297E-11
R (M) 2 0 . 86 TSL (K) 3 4 6 . 8 QB (W/M2) 0 . 1 87E+04 QT (W/M2) - 0 . 297E-11
R (M) 22 . 6 0 TSL (K) 3 4 0 . 5 QB (W/M2) 0 . 165E+04 QT (W/M2) - 0 . 297E-11
R (M) 24 . 34 TSL (K) 3 3 5 . 4 QB (W/M2) 0 . 147E+04 QT (W/M2) - 0 . 297E-11
R (M) 26 . 0 8 TSL (K) 3 3 1 . 1 QB (W/M2) 0 . 132E+04 QT (W/M2) - 0 . 297E-11
R (M) 2 7 . 82 TSL (K) 3 2 7 . 6 QB (W/M2) 0 . 1 19E+04 QT (W/M2) - 0 . 297E-11
R (M) 29 . 5 6 TSL (K) 3 24 . 6 QB (W/M2) 0 . 10 8E+04 QT (W/M2) - 0 . 297E-11
R (M) 3 1 . 2 9 TSL (K) 3 22 . 0 QB (W/M2) 0 . 994E+03 QT (W/M2) - 0 . 297E-11
R (M) 33 . 03 TSL (K) 3 1 9 . 8 QB (W/M2) 0 . 9 16E+03 QT (W/M2) - 0 . 297E-11
R (M) 34 . 7 7 TSL ( K) 3 1 7 . 9 QB (W/M2) 0 . 849E+03 QT (W/M2) - 0 . 297E-ll
R (M) 36 . 51 TSL ( K) 3 1 6 . 2 QB (W/M2) 0 . 790E+03 QT (W/M2) - 0 . 297E-ll
R (M) 3 8 . 2 5 TSL (K) 3 1 4 . 8 QB (W/M2) 0 . 7 3 7E+03 QT (W/M2) - 0 . 297E-ll
R (M) 3 9 . 99 TSL (K) 3 1 3 . 5 QB (W/M2) 0 . 6 9 1E+03 QT (W/M2) - 0 . 297E-ll
R (M) 4 1 . 7 3 TSL (K) 3 1 2 . 3 QB (W/M2) 0 . 6 5 0E+03 QT (W/M2) - 0 . 297E-ll
R (M) 4 3 . 4 6 TSL (K) 3 1 1 . 3 QB (W/M2) 0 . 6 13E+03 QT (W/M2) - 0 . 297E-ll
R (M) 45 . 2 0 TSL (K) 3 10 . 3 QB (W/M2) 0 . 5 8 0E+03 QT (W/M2) - 0 . 297E-ll
R (M) 46 . 94 TSL (K) 3 0 9 . 5 QB (W/M2) 0 . 5 49E+03 QT (W/M2) - 0 . 297E-ll
R (M) 4 8 . 6 8 TSL (K) 3 0 8 . 3 QB (W/M2) 0 . 5 25E+03 QT (W/M2) - 0 . 297E-ll
R (M) 5 0 . 4 2 TSL (K) 2 9 6 . 2 QB (W/M2) 0 . 820E+02 QT (W/M2) -0. 297E-11

TIME (S)= 4 8 0 . 0 0 0 0 LYR TEMP (K)= 530 . 8 LYR HT (M) 5 . 94

LYR MASS (KG)=0. 112E+05 FIRE OUTPUT (W) = 0 . 7059E+08 VENT AREA (M2) 28.20
LINK = 1 LINK TEMP (K) 7 8 4 . 4 1 JET VELOCITY (M/S) = 5 . 462
JET TEMP (K) = 785.2 TIME LINK 1 OPENS EQUALS 4 1 . 7 0 9 8 (S)
R (M) 0 . 0 0 TSL (K) 8 3 7 . 6 Q B (W/M2) 0 . 137E+05 QT (W/M2) - 0 . 2 9 7E-11
R (M) 1 . 74 TSL (K) 7 8 9 . 0 QB (W/M2) 0 . 128E+05 QT (W/M2) - 0 . 297E-11
R (M) 3 . 4 8 TSL (K) 729 . 0 QB (W/M2) 0 . 1 17E+05 QT (W/M2) -0. 297E-11
R (M) 5 . 22 TSL (K) 6 5 9 . 2 QB (W/M2) 0 . 103E+05 QT (W/M2) - 0 . 297E-11
R (M) 6 . 9 5 TSL (K) 5 9 3 . 8 QB (W/M2) 0 . 8 76E+04 QT (W/M2) - 0 . 297E-11
R (M) 8 . 6 9 TSL (K) 5 3 7 . 8 QB (W/M2) 0 . 736E+04 QT (W/M2) - 0 . 297E-11
R (M) 1 0 . 4 3 TSL (K) 4 9 2 . 4 QB (W/M2) 0 . 6 13E+04 QT (W/M2) - 0 . 297E-11
R (M) 12 . 1 7 TSL (K) 4 5 6 . 6 QB (W/M2) 0 . 5 11E+04 QT (W/M2) - 0 . 297E-11
R (M) 1 3 . 9 1 TSL (K) 4 2 8 . 8 QB (W/M2) 0 . 429E+04 QT (W/M2) - 0 . 297E-11
R (M) 15 . 6 5 TSL (K) 4 0 7 . 2 QB (W/M2) 0 . 363E+04 QT (W/M2) - 0 . 297E-11
R (M) 1 7 . 39 TSL (K) 3 9 0 . 4 QB (W/M2) 0 . 3 11E+04 QT (W/M2) - 0 . 297E-11
R (M) 19 . 12 TSL (K) 3 7 7 . 0 QB (W/M2) 0 . 2 70E+04 QT (W/M2) - 0 . 297E-11
R (M) 2 0 . 86 TSL (K) 3 6 6 . 4 QB (W/M2) 0 . 236E+04 QT (W/M2) - 0 . 297E-ll
R (M) 22 . 60 TSL (K) 3 5 7 . 9 QB (W/M2) 0 . 209E+04 QT (W/M2) - 0 . 297E-ll
R (M) 24 . 34 TSL (K) 3 5 0 . 9 QB (W/M2) 0 . 1 86E+04 QT (W/M2) - 0 . 297E-ll
R (M) 26 . 0 8 TSL (K) 345 . 1 QB (W/M2) 0 . 167E+04 QT (W/M2) - 0 . 297E-ll
R (M) 2 7 . 82 TSL (K) 340 . 2 QB (W/M2) 0 . 152E+04 QT (W/M2) - 0 . 297E-ll
R (M) 29 . 5 6 TSL ( K) 3 3 6 . 1 QB (W/M2) 0 . 1 3 8E+04 QT (W/M2) - 0 . 297E-ll
R (M) 3 1 . 2 9 TSL (K) 332 . 6 QB (W/M2) 0 . 127E+04 QT (W/M2) - 0 . 297E-ll

FIGURE D.IO(i) Continued

2021 Edition
204-68 SMOKE AND HEAT VENTLNG

R (M) 33 . 0 3 TSL ( K ) 329 . 6 QB (W/M2) 0 . 1 1 7E+04 QT (W/M2 ) -0. 297E-ll

R (M) 34 . 7 7 TSL ( K ) 3 2 7 . 0 QB (W/M2) 0 . 109E+04 QT (W/M2 ) -0. 297E-ll
R (M) 36 . 5 1 TSL ( K ) 324 . 7 QB (W/M2) 0 . 101E+04 QT (W/M2 ) -0. 297E-ll
R (M) 3 8 . 2 5 TSL ( K ) 322 . 7 QB (W/M2) 0 . 944E+03 QT (W/M2) -0. 297E-ll
R (M) 3 9 . 99 TSL (K) 32 0 . 9 QB (W/M2) 0 . 886E+03 QT (W/M2) -0. 297E-ll
R (M) 4 1 . 7 3 TSL (K) 3 1 9 . 3 QB (W/M2) 0 . 8 33E+03 QT (W/M2) -0. 297E-ll
R (M) 4 3 . 4 6 TSL (K) 3 1 7 . 8 QB (W/M2) 0 . 786E+03 QT (W/M2) -0. 297E-ll
R (M) 45 . 2 0 TSL ( K) 3 1 6 . 5 QB (W/M2) 0 . 743E+03 QT (W/M2) -0. 297E-ll
R (M) 46 . 94 TSL (K) 3 1 5 . 4 QB (W/M2) 0 . 705E+03 QT (W/M2) -0. 297E-ll
R (M) 4 8 . 6 8 TSL (K) 3 1 3 . 9 QB (W/M2) 0 . 6 73E+03 QT (W/M2) -0. 297E-ll
R (M) 50.42 TSL (K) 2 9 7 . 1 QB (W/M2) 0 . 1 0 8E+03 QT (W/M2) -0. 297E-ll

TIME ( S ) = 5 4 0 . 0 0 0 0 LYR TEMP ( K ) = 5 8 6 . 5 LYR H T (M) = 5 . 20

LYR MASS (KG)=0. 125E+05 FIRE OUTPUT (W) = 0 . 9 0 7 3E+08 VENT AREA (M2) 28.20
LINK = 1 LINK TEMP (K) 9 1 5 . 64 JET VELOCITY (M/S) = 6 . 041
JET TEMP (K) = 916.6 TIME LINK 1 OPENS EQUALS 4 1 . 70 9 8 ( S )
R (M) 0 . 00 TSL ( K ) 9 2 1 . 9 QB (W/M2) 0 . 146E+05 QT (W/M2) - 0 . 2 9 7E-11
R (M) 1 . 74 TSL ( K ) 8 7 0 . 2 QB (W/M2) 0 . 1 37E+05 QT (W/M2) -0. 297E-ll
R (M) 3 . 4 8 TSL ( K ) 806 . 7 QB (W/M2) 0 . 126E+05 QT (W/M2) -0. 297E-ll
R (M) 5 . 22 TSL ( K ) 7 3 1 . 6 QB (W/M2) 0 . 1 12E+05 QT (W/M2) -0. 297E-ll
R (M) 6 . 95 TSL ( K ) 6 6 0 . 0 QB (W/M2) 0 . 9 72E+04 QT (W/M2) -0. 297E-ll
R (M) 8 . 6 9 TSL ( K ) 5 9 7 . 0 QB (W/M2) 0 . 834E+04 QT (W/M2) -0. 297E-ll
R (M) 10 . 4 3 TSL ( K ) 5 4 4 . 2 QB (W/M2) 0 . 709E+04 QT (W/M2) -0. 297E-ll
R (M) 1 2 . 1 7 TSL ( K ) 5 0 1 . 5 QB (W/M2) 0 . 60 1E+04 QT (W/M2) -0. 297E-ll
R (M) 1 3 . 9 1 TSL ( K ) 4 6 7 . 5 QB (W/M2) 0 . 5 11E+04 QT (W/M2) -0. 297E-ll
R (M) 1 5 . 6 5 TSL ( K ) 440 . 7 QB (W/M2) 0 . 43 7E+04 QT (W/M2) -0. 297E-ll
R (M) 1 7 . 39 TSL ( K ) 4 1 9 . 5 QB (W/M2) 0 . 3 77E+04 QT (W/M2) -0. 297E-ll
R (M) 19 . 12 TSL ( K ) 4 0 2 . 6 QB (W/M2) 0 . 329E+04 QT (W/M2) -0. 297E-ll
R (M) 20 . 86 TSL ( K ) 3 8 9 . 0 QB (W/M2) 0 . 290E+04 QT (W/M2) -0. 297E-ll
R (M) 22 . 6 0 TSL ( K ) 3 7 8 . 0 QB (W/M2) 0 . 25 7E+04 QT (W/M2) -0. 297E-ll
R (M) 24 . 3 4 TSL ( K ) 3 6 8 . 9 QB (W/M2 ) 0 . 23 0E+04 QT (W/M2 ) -0. 297E-ll
R (M) 26 . 0 8 TSL ( K ) 3 6 1 . 4 QB (W/M2 ) 0 . 20 7E+04 QT (W/M2 ) -0. 297E-ll
R (M) 2 7 . 82 TSL ( K ) 3 5 5 . 0 QB (W/M2 ) 0 . 1 8 8E+04 QT (W/M2 ) -0. 297E-ll
R (M) 29 . 5 6 TSL ( K ) 349 . 7 QB (W/M2 ) 0 . 172E+04 QT (W/M2 ) -0. 297E-ll
R (M) 3 1 . 2 9 TSL ( K ) 345 . 1 QB (W/M2 ) 0 . 15 8E+04 QT (W/M2 ) -0. 297E-ll
R (M) 3 3 . 0 3 TSL ( K ) 3 4 1 . 1 QB (W/M2 ) 0 . 146E+04 QT (W/M2 ) -0. 297E-ll
R (M) 34 . 7 7 TSL ( K ) 3 3 7 . 7 QB (W/M2 ) 0 . 136E+04 QT (W/M2 ) -0. 297E-ll
R (M) 3 6 . 5 1 TSL ( K ) 334 . 7 QB (W/M2 ) 0 . 126E+04 QT (W/M2 ) -0. 297E-ll
R (M) 3 8 . 2 5 TSL ( K ) 3 3 2 . 0 QB (W/M2 ) 0 . 1 1 8E+04 QT (W/M2 ) -0. 297E-ll
R (M) 3 9 . 9 9 TSL ( K ) 329 . 6 QB (W/M2) 0 . 1 1 1E+04 QT (W/M2) - 0 . 2 9 7E-ll
R (M) 4 1 . 7 3 TSL ( K ) 3 2 7 . 5 QB (W/M2) 0 . 104E+04 QT (W/M2) - 0 . 2 9 7E-ll
R (M) 43 . 4 6 TSL ( K ) 325 . 6 QB (W/M2) 0 . 9 86E+03 QT (W/M2) - 0 . 2 9 7E-ll
R (M) 45 . 2 0 TSL ( K ) 3 2 3 . 9 QB (W/M2) 0 . 933E+03 QT (W/M2) - 0 . 2 9 7E-ll
R (M) 46 . 9 4 TSL ( K ) 3 2 2 . 4 QB (W/M2) 0 . 8 85E+03 QT (W/M2) - 0 . 2 9 7E-ll
R (M) 4 8 . 6 8 TSL ( K ) 320 . 7 QB (W/M2) 0 . 844E+03 QT (W/M2) - 0 . 2 9 7E-ll
R (M) 5 0 . 4 2 TSL ( K ) 2 9 8 . 2 QB (W/M2) 0 . 138E+03 QT (W/M2) - 0 . 2 9 7E-ll

TIME ( S ) = 6 0 0 . 0 0 0 0 LYR TEMP (K)= 6 4 9 . 9 LYR HT (M) 4.57

LYR MASS (KG)=0. 131E+05 FIRE OUTPUT ( W ) = 0 . 9 999E+08 VENT AREA (M2) 28.20
LINK = 1 LINK TEMP ( K ) 1029 . 1 1 JET VELOCITY (M/S) = 6 . 247
JET TEMP (K) = 1029.6 TIME LINK 1 OPENS EQUALS 4 1 . 70 9 8 ( S )
R (M) 0 . 0 0 TSL (K) 9 7 6 . 8 QB (W/M2 ) 0 . 123E+05 QT (W/M2 ) - 0 . 2 9 7E-11
R (M) 1 . 74 TSL (K) 9 2 3 . 1 QB (W/M2 ) 0 . 115E+05 QT (W/M2 ) -0. 297E-ll
R (M) 3 . 4 8 TSL (K) 8 5 9 . 1 QB (W/M2 ) 0 . 107E+05 QT (W/M2 ) -0. 297E-ll
R (M) 5 . 22 TSL (K) 7 8 3 . 3 QB (W/M2 ) 0 . 9 65E+04 QT (W/M2 ) -0. 297E-ll
R (M) 6 . 9 5 TSL (K) 7 1 0 . 1 QB (W/M2 ) 0 . 86 1E+04 QT (W/M2 ) -0. 297E-ll
R (M) 8 . 6 9 TSL (K) 644 . 7 QB (W/M2 ) 0 . 76 1E+04 QT (W/M2 ) -0. 297E-ll
R (M) 10 . 4 3 TSL (K) 5 8 8 . 5 QB (W/M2 ) 0 . 6 67E+04 QT (W/M2 ) -0. 297E-ll
R (M) 12 . 1 7 TSL ( K) 5 4 1 . 7 QB (W/M2 ) 0 . 5 82E+04 QT (W/M2 ) -0. 297E-ll
R (M) 13 . 9 1 TSL ( K) 5 0 3 . 6 QB (W/M2 ) 0 . 5 06E+04 QT (W/M2 ) -0. 297E-ll
R (M) 15 . 6 5 TSL ( K) 4 7 2 . 9 QB (W/M2 ) 0 . 442E+04 QT (W/M2 ) -0. 297E-ll
R (M) 1 7 . 39 TSL (K) 4 4 8 . 1 QB (W/M2 ) 0 . 3 87E+04 QT (W/M2 ) -0. 297E-ll
R (M) 1 9 . 12 TSL (K) 4 2 8 . 2 QB (W/M2 ) 0 . 342E+04 QT (W/M2 ) -0. 297E-ll
R (M) 20 . 86 TSL (K) 4 1 1 . 9 QB (W/M2 ) 0 . 304E+04 QT (W/M2 ) -0. 297E-ll

FIGURE D.IO(i) Continued

2021 Edition
 ANNEX E 204-69

R (M} 2 2 . 6 0 TSL (K) 3 9 8 . 6 QB (W/M2) 0 . 2 72E+04 QT (l;/M2} - 0 . 2 9 7E-ll

R (M} 2 4 . 3 4 TSL (K) 3 8 7 . 6 QB (W/M2) 0 . 245E+04 QT (l;/M2} - 0 . 2 9 7E-ll
R (M) 2 6 . 0 8 TSL (K) 3 7 8 . 4 QB (W/M2) 0 . 223E+04 QT (W/M2) -0 .297E-11
R (M) 2 7 . 82 TSL (K) 3 7 0 . 6 QB (W/M2) 0 . 203E+04 QT (W/M2) -0 .297E-11
R (M) 2 9 . 5 6 TSL (K) 364 . 0 QB (W/M2) 0 . 1 87E+04 QT (W/M2) -0 .297E-11
R (M) 3 1 . 2 9 TSL (K) 3 5 8 . 4 QB (W/M2) 0 . 172E+04 QT (W/M2) -0 .297E-11
R (M) 3 3 . 0 3 TSL (K) 3 5 3 . 5 QB (W/M2) 0 . 1 60E+04 QT (W/M2) -0 .297E-11
R (M) 3 4 . 7 7 TSL (K) 349 . 2 QB (W/M2) 0 . 149E+04 QT (W/M2) -0 .297E-11
R (M) 3 6 . 5 1 TSL (K) 3 4 5 . 4 QB (W/M2) 0 . 139E+04 QT (W/M2) -0 .297E-11
R (M) 3 8 . 2 5 TSL (K) 342 . 1 QB (W/M2) 0 . 1 3 0E+04 QT (W/M2) -0 .297E-11
R (M) 3 9 . 9 9 TSL (K) 3 3 9 . 2 QB (W/M2) 0 . 123E+04 QT (W/M2) -0 .297E-11
R (M) 4 1 . 7 3 TSL (K) 3 3 6 . 5 QB (W/M2) 0 . 1 1 6E+04 QT (W/M2) -0 .297E-11
R (M) 4 3 . 4 6 TSL (K) 334 . 1 QB (W/M2) 0 . 1 09E+04 QT (W/M2) -0 .297E-11
R (M) 4 5 . 2 0 TSL (K) 332 . 0 QB (W/M2) 0 . 1 04E+04 QT (W/M2) -0 .297E-11
R (M) 4 6 . 9 4 TSL (K) 3 3 0 . 1 QB (W/M2) 0 . 9 86E+03 QT (W/M2) -0 .297E-11
R (M) 4 8 . 68 TSL (K) 3 2 8 . 0 QB (W/M2) 0 . 941E+03 QT (W/M2) -0 .297E-11
R (M) 5 0 . 4 2 TSL (K) 2 9 9 . 4 QB (W/M2) 0 . 147E+03 QT (W/M2) -0 .297E-11

FIGURE D.IO(i) Contirmed

D.ll References for Annex D. E.2 Sources of Data. The following sources of data appear in
their approxin1ate order of priot·ity, given equal quality of data
(1) Purser, D. A. and J. L . McAllister. "Assessment of Hazards
acquisition:
to Occupants from Smoke, Toxic Gases and Heat," Chap­
ter 63, SFPE Handbook of Fin; Pmtection Engi.nee1ing, 5th (1) Acttml tests of the array involved
edition, Hurley et al. editors, SFPE, Gaithersburg, MD, (2) Acmal tests of similar arrays
2016. (3) Algorithms derived fi·om tests of arrays having similar
(2) Peacock, R. D., et al. Software User's Guirk fm· the Hazard I fuels and dimensional characteristics
Fie Hazm·d Asses.nnent Method, Version 1 . 1 , NIST Hand­
r (4) Calculations based on tested properties and materials and
book 146, Volume I, United States Department of expected flame flux
Commerce, National Institute of Standards and Technol­ (5) Mathematical models of fire spread and development
ogy, Gaithersburg, MD, 1991.
E.3 Actual Tests of the Array Involved. Where an acmal calo­
(3) Cooper, L. Y , and W. D. Davis. "Estimating the Environ­
rific test of the specific array under consideration has been
ment and the Response of Sprinkler Links in Compart­
conducted and the data are in a form that can be expt·essed as
ment Fires with Draft Curtains and Fusible Link-Actuated
rate of heat release, the data can be used as input for the meth­
Ceiling Vents - Part II: User Guide for the Computer
ods in this standard. Because acmal test data seldom produce
Code LAVENT," NISTIR 89-4122, United States Depart­
the steady state assumed for a limited-growth fire or the square­
ment of Commerce, National Instimte of Standards and
of-time growth assumed for a continuous-growth fire, engineer­
Technology, Gaithersburg, MD, july 1989.
ing judgment is usually needed to derive the actual input
necessary if eithet· of these approaches is used. If LAVENT or
Annex E Predicting the Rate of Heat Release of Fires another computer model capable of responding to a rate of
This annex is not a part of the 1·equin;ments of this NFPA document heat release versus time curve is used, the data can be used
but is includedfor informational pwposes only. directly. Currently there is a listing of limited information fi·om
tests of specific arrays. Some test data can be found in technical
E. I Introduction. Annex E presents techniques for estimating reports. Alternatively, individual tests can be conducted.
the heat release rate of various fuel arrays likely to be present
Many fire tests do not include a direct measurement of rate
in buildings where smoke and heat venting is a potential fire
of heat release. In some cases, that measure can be derived,
safety provision. This annex primarily addresses the estimation
based on measurement of mass loss rate using the following
of fuel concentrations found in stot·age and manufacnu·ing
equation:
locations. NFPA 92 addresses the types of fuel arrays more
common to the types of building situations covered by that
document. [E.3a]
This standard is applicable to simations in which the hot Q = m(hJ
layer does not enhance the burning rate. The methods provi­
ded in this annex for estimating the t·ate of heat release, there­ where:
fore, are based on free burning conditions in which no ceiling Q = total heat release rate (kW)
or hot gas layer effects are involved. It is assumed, therefore , m = mass loss rate (kg/sec)
that the burning t·ate is relatively unaffected by the hot layec h, = heat of combustion (kj/kg)

2021 Edition
204-70 SMOKE AND HEAT VENTLNG

In other cases, a direct mea5urement can be derived based E.5 Algorithms Derived from Tests of Arrays Having Similar
on measurement of flame height above the base of the fire as Fuels and Dimensional Characteristics.
follows:
E.5.1 Pool Frres. In many cases, the rate of heat release of a
tested array has been divided by a common dimension, such as
[E.3b] occupied floor at·ea, to derive a normalized rate of heat release
2 per unit area. The rate of heat release of pool fires is the best
Q = 37(L + l .02D)5 1
documented and accepted algorithm in this class.
where: An equation for the mass release t·ate from a pool fire is as
Q = total heat release rate (kW) follows [Babrauskas, 2016]:
L = mean flame height above the base of the fire (m)
D = base diameter of the fire (m)
[E.5.1]
E.4 Actual Tests of Arrays Similar to That Involved. Where an
actual calorific test of the specific array under consideration
cannot be found, it might be possible to find data on one or
more tests that are similar to the fuel of concern in important The variables m';., and (k/3JD for Equation E.5.1 are as
matters such as type of fuel, arrangement, ot· ignition scenario. shown in Table E.5.1.
The more the actual tests are similar to the fuel of concern, the
higher is the confidence that can be placed in the derived rate The ma5s rates derived from Equation E.5.1 are converted to
of heat release. Added engineering judgment, however, might rates of heat release using Equation E.3a and the heat of
be needed to adjust the test data to that approximating the fuel combustion, h<> from Table E.5.1. The rate of heat release per
of concern. If the rate of heat release has not been measured unit area times the area of the pool yields heat release data for
directly, it can be estimated using the methods provided in the anticipated fit·e.
Section E.3.

Table E.5.1 Data for Large Pool Burning Rate Estimates

Density h, kj3D
Material (kg/ru3) (MJ/kg) th. '
(ru )

Cryogenics"
Liquid H2 70 120.0 0.017 6.1
LNG (mostly CH4 ) 415 50.0 0.078 l.l
LPG (mostly C3H8) 585 46.0 0.099 1.4
Alcohols
Methanol (CH30H) 796 20.0 0.017 oob

Ethanol (�H;OH) 794 26.8 0.015 oob

Simple organic fuels

Butane (C4H 10) 573 45.7 0.078 2.7
Benzene (C5H6) 874 40.1 0.085 2.7
Hexane (C6H14) 650 44.7 0.074 1.9
Heptane (C7H16) 675 44.6 0.101 1.]
Xylene (C8H10) 870 40.8 0.090 1.4
Acetone (C3H60 ) 791 25.8 0.041 1.9
Dioxane (C4H802) 1035 26.2 0.018° 5.4<
Diethyl ether (C4H100 ) 714 34.2 0.085 0.7
Petroleum products
Benzine 740 44.7 0.048 3.6
Gasoline 740 43.7 0.055 2.1
Kerosene 820 43.2 0.039 3.5
JP-4 760 43.5 0.051 3.6
JP-5 810 43.0 0.054 1.6
TransfOtmer oil, hydrocarbon 760 46.4 0.039° 0.7°
Fuel oil, heavy 940-1000 39.7 0.035 1.7
Crude oil 830-880 42.5-42.7 0.022-0.045 2.8
Solids
Polymethylmethacrylate (C)-1802), 1184 24.9 0.020 3.3
Polypropylene (C3H6) , 905 43.2 O.Ql8
Polysl)�·ene (C8H8)" 1050 39.7 0.034
a For pools on dry land, not over water.
b Value is independent of the diameter in a turbulent regimen.
c Estimate is uncenain, since only two data points are available.

2021 Edition
 ANNEX E 204-71

E.5.2 Other Normalized Data. Other data based on burning Table E.5.2(b) Unit Heat Release Rate for Commodities
•-are per unit area in tests have been developed. Table E.5.2(a)
and Table E.5.2(b) list these data. Heat Release Rate
Commodity (kW per m2 of floor area)*
Table E.5.2(a) Unit Heat Release Rates for Fuels Burning in
Wood pallets, stacked 0.46 m high 1,420
the Open
(6%-12% moisture)
Wood pallets, stacked 1.52 m high 4,000
Heat Release Rate
(6%-12% moisture)
Commodity (kW)
Wood pallets, stacked 3.05 111 high 6,800
Wood or PMMA* (vertical) (6%-12% moisture)
0.61 m height 100/m ofwidth Wood pallets, stacked 4.88 111 high 1 0,200
1.83 m height 240/ m of width (6%-12% moisture)
2.44 m height 620/m ofwidth Mail bags, filled, stored 1.52 m 400
3.66 m height 1000/m ofwidth high
Woodor PMMA Cartons, compartmented, stacked 1,700
Top of horizontal surface 720/m2 of surface 4.5 m high
Solid polystyrene (vertical) PE letter trays, filled, stacked 8,500
0.61 m height 220/m ofwidth 1 .5 111 high on cart
1.83 m height 450/m ofwidth PE trash barrels in cartons, 2,000
2.44 m height 1400/m ofwidth stacked 4.5 m high
3.66 m height 2400/m ofwidth PE fiberglass shower stalls in 1,400
Solid polysryt-ene (horizontal) 1400/m2 of surface cartons, stacked 4.6 m high
Solid polypropylene (vertical) FRP bottles packed in cartons, 6,200
stacked 4.6 m high
0.61 m height 220/m ofwidth
PE bottles in cartons, stacked 2,000
1.83 m height 350/m ofwidth
4.5 m high
2.44 m height 970/m of width
PU insulation board, rigid foam, 1,900
3.66 m height 1600/m ofwidth
stacked 4.6 m high
Solid polypropylene 800/m2 of surface
FRP jars packed in cartons, 1 4,200
(horizontal)
stacked 4.6 m high
* PMMA: polymethyl methacrylate (Plexiglas, Lucite, acrylic). PS ntbs nested in cartons, stacked 5,400
4.2 m high
PS toy parts in cartons, stacked 2,000
E.5.3 Other Useful Data. Examples of other data that are not 4.5 m high
normalized but that might be useful in developing the rate of PS insulation board, rigid foam , 3,300
heat release curve are included in Table E.5.3(a) through Table stacked 4.2 m high
E.5.3(d). FRP bottles packed in cartons, 3,400
E.6 Calculated Fire Description Based on Tested Properties. stacked 4.6 m high
FRP rubs packed in cartons, 4,400
E.6.1 Background. It is possible to make general estimates of stacked 4.6 m high
the rate of heat release of burning materials based on the fire PP and PE film in rolls, stacked 6,200
properties of that material. The fire properties involved are 4 . 1 m high
determined by small-scale tests. The most important of these Methyl alcohol 600
tests are the cal01·imeter tests involving both oxygen depletion Gasoline 2,500
calorimetry and the application of external heat flux to the Kerosene 1,700
sample while determining time to ignition, rate of mass release , Fuel oil, no. 2 1 ,700
and rate of heat release for the specific applied flux. Most
prominent of the current test apparatus are the cone calorime­
PE: polyethylene. PP: polypropylene. PS: polystyrene. PU:
ter (ASTM £ 1 354, Standard Test Method fo1· Heat and Vi5ible Smoke
polyurethane. fiberglass-reinforced polyester.
FRP:

Release Rates fo·r MateriaL5 and Products U5ing an Oxygen Consump­

*Hear release rate per unit floor area offi.llly involved combustibles,
tion Calm"imeter) and the Factory Mutual Fire Propagation Appa­
based on negligible radiative feedback from the surroundings and
rants [ASTM £2058, Standanl Test Methods for Measurement of
100 percent combustion efficiency.
Synthetic Polyme1· Material Flammability Using a Fi1·e Pmpagation
Apparatus (FPA)].
flame travel) apparatus (ASTM £1321, Standard 1est Method for
In addition to the directly meamred properties, it is possible Determining Material Ignition and Flame Spread Properties) .
to derive ignition temperantre, critical ignition flux, effective
thermal inertia (kc), heat of combustion, and heat of gasifica­ This section presents a concept of the use of fire property
tion based on •-esults from these calorimeters. Properties not test data as the basis of an analytical evaluation of the rate of
derivable from these calorimeters and essential to determining heat release involved in the use of a tested material. The
flame spread in directions not concurrent with the flow of the approach outlined in this section is based on that presented by
flame can be obtained from the LIFT (lateral ignition and Nelson and Forssell f l 994].

2021 Edition
204-72 SMOKE AND HEAT VENTLNG
Table E.5.3(a) Characteristics of Ignition Sources than its own flame) is impacted by a flux in the range of
25 kW/m 2 to 50 kW/m 2• If the fire is in a space and conditions
Typical Maximum Maximum are approaching flashover� the flux can increase to the range of
Heat Burn Flame Flame Heat 50 kW/m 2 to 75 kW/m2 . In a fully developed, postflashover
Output Timea Height Wi dth Flux fire, a range of 75 kW/m2 to greater man 100 kW/m2 can be
2
Fuel (W) (sec) (mm) (mm) (kW/ m ) expected. The following is a discussion of the individual prop­
erties measured or derived and the usual form used to report
Cigarette
puffed, l.llaidgon(notsolid me property.
surface)dry
Bone 5 1,200 42
Rate of Heat Release. The rate of heat release is determined by
oxygen depletion calorimetry. Each test is run at a user�pecific
Conditioned
relative hwnidity to 50% 5 1 ,200 35
incident flux, either for a pt·edetennined period of time ot·
until the sample is consumed. The complete results are presen­
Methenamine
0.15 g pill, 45 90 4
ted in the form of a plot of heat release rate versus time, with
the level of applied flux noted. In some cases, the rate of heat
Match,
on wooden
solid surf a (laid
ce) 80 2030 30 14 18-20
release for several tests of the same material at different levels
Wood criPartbs, BS of applied flux is plotted on a single curve for comparison.
5852 2 Figure E.6.2 is an example of such a plotting.
No. 5 crib,
4 8.5 g 1,000 190 15°
Often, only the peak rate of heat release at a specific flux is
No.
No. 6
crib,
crib, g 17
60
g 1,900
2,600
200
190
l7b
20b
reported. Table E.6.2(b) is an example.
No. 7 crib, 126 g 6,400 350 25° Mass Loss Rate. Mass loss rate is detet·mined by a load cell.
Crumpled
bag, 6g brown lunch 1,200 80
The meiliod of reporting is identical to that for rate of heat
release. In the typical situation in which the material has a
Cnm1pled
4.5 g wax papet;
(tight) 1,800 25
consistent heat of combustion, the curves for mass loss t·ate and
rate of heat release are similar in shape.
Crumpled
4.5 g wax papet;
(loose) 5,300 20
Time to Ignition. Time to ignition is reported for each individ­
Folded double-sheet
newspaper, 22 g 4,000 100 ual test and applied flux level conducted.

(bottom
Crumpled ignition)
double-sheet 7,400 40
. fective Thermal Inertia (kpc). Effective thermal inertia is a
l!j
measurement of the heat rise response of the tested material to
newspaper,
(top ignition) 22 g me heat flux imposed on the sample. It is derived at the time
of ignition and is based on me ratio of the actual incident flux
CrW11pled
newspaper, double-sheer
22 g
17,000 20
to me critical ignition flux and the time to ignition. A series of
tests at different levels of applied flux is necessary to der·ive me
(bottom ignition)
Polyethylene 50,000 200c 550 200 35d
effective thermal inertia. Effective thermal inertia derived in
this manner can differ from, and be preferable to, handbook
wa�tebasket,
filled with 12
285
milk g, data for the values of k, p, and c that are derived without a fire.
cartons
Plastic tra�h (390 g) filled
bags, 120,000 200<
Heat of Combustion. Heat of combustion is derived by dividing
the measured rate of heat release by the measured mass loss
with cellulosic
( 1.2-14 kg)e trash to 50,00
rate. It is normally reported as a single value, unless me sample
is a composite material and the rates of heat release and mass
0
loss vary significantly with time and exposure .
3Time duration ofsignificant flaming.
bMeasured from mm away. 25 Heat of Gasification. Heat of gasification is the flux needed to
<Total burn time in excess of seconds.
1800 pyrolyze a unit mass of fuel. It is derived as a heat balance and
dAs measured on simulation burner. is usually reported as a single value in terms of me amount of
vary
eResults greatly with packing density. energy per unit mass of material released (e.g., \0/g).

Critical Ignition Flux. Critical ignition flux is the minimum

E.6.2 Discussion of Measured Properties. Table E.6.2(a) lists level of incident flttx on the sample needed to ignite me
the type of fire properties obtainable from the cone calorime­ sample, given an unlimited time of application. At incident flux
ter [NFPA 287] , the Factory Mutual Fire Propagation Appara­ levels less d1an me critical ignition flux, ignition does not take
tus [ASTM E2058, StandaTd Test Methods joT Measumnent of place.
Synthetic Polymer Mate?ial Flammability Using a FiTe Propagation
Appamtus (FPA)], and similar instruments. Ignition Temperatun:. Ignition temperature of a sample is the
surface temperature at which flame occurs. This sample mate­
In Table E.6.2(a), the rate of heat release, mass loss, and rial value is independent of me incident flux and is derivable
time to ignition are functions of d1e externally applied incident from me calor·imeter tests, the LIFT apparatus test, and oilier
radiant heat flux imposed on the tested sample. The purpose tests. It is derived from the time to ignite in a given test, me
of the externally applied flux is to simulate the fire environ­ applied flttx in mat test, and the effective d1ermal inertia of me
ment surrounding a burning item. sample. It is reported at a single temperature. If the test
includes a pilot flame or spark, me reported temperature is for
In general, it can be estimated that a free-burning fuel pack­
piloted ignition; if there is no pilot present, me temperature is
age (i.e., one that burns in the open and is not affected by
fix auto-ignition. Most available data are fix piloted ignition.
ener·gy feedback fi·om a hot gas layer of a heat source other

2021 Edition
 ANNEX E 204-73

Table E.5.3(b) Characteristics of Typical Furnishings as Ignition Sources

Maximum Maximum
Total Rate of Heat Thermal Radiation
Total Mass Heat Content Release to Center of Floor*
Fuel (kg) (MJ) (kW) (kW/m2)

'1\Tastepaper basket 0.73-1.04 0.7-7.3 4-18 0.1

Curtains, velvet/ 1.9 24 1 60--240 1.3-3.4
cotton
Curtains, acrylic/ 1.4 15-16 1 30-- 150 0.9-1.2
cotton
1V set 27-33 145-150 1 20--290 0.3-2.6
Chair mockup 1.36 21-22 63--66 0.4-0.5
Sofa mockup 2.8 42 130 0.9
Arm chair 26 18 160 1.2
Christmas tree, dry 6.5-7.4 1 1-41 500--650 3.4-14
*Measured at approximately 2 m from the burning object.

E.6.3 Ignition. Equations for time to ignition, t1r: are given for Table E.5.3(c) Maximum Heat Release Rates from Fire
both thermally thin and thermally thick materials, defined as Detection Institute Analysis
follows. For materials of intermediate depth, estimates for t1g
necessitate considerations beyond the scope of this presenta­ Approximate
tion [Drysdale, 201 1 , Carslaw and Jaeger, 1959]. Value
TherrnaUy Thin Materials. Relative to ignition from a constant Fuel (kW)
incident heat flux, q1, at the exposed surface and with relatively Medium wastebasket with milk cartons 100
small heat u-ansfer losses at the unexposed surface, a thet-mally Large barrel with milk cartons 140
thin material is one whose temperature is relatively uniform Upholstered chair with polyurethane foam 350
throughout its entire thickness, l, at t = t1w For example, at t = tg
1 :
latex foam mattress (heat at room door) 1200
Furnished living room (heat at open door) 4000--8000
[E.6.3a]
TN
.:
posnl
(
- TIHII'XjJOSI'd = T1g - Tmuxpo.fl'l'l < 0 . 1 T•g - T o
)
a thickness, l, is considered to be thermally thick if the increase
Equation E.6.3a can be used to show that a material is ther­ in temperature of the unexposed surface is relatively small
mally thin [Carslaw and Jaeger, 19591 where: compared to that of the exposed surface at t = t11! For example,
at t = t1r:

[E.6.3b]
[E.6.3d]

0
(
T'11111!A1i0Sid - T < 0. 1 Tt:l.
f 0
)Q.
" Vtl
) (
- T = 0.1 T - T
tg (I
)
For example, for sheets of maple or oak wood (where the
thermal diffusivity = 1.28 1 07m2/sec [Hurley et al., 20161), if t;g Equation E.6.3d can be used to show that a material is ther­
= 35 sec is measured in a piloted ignition test, then, according
mally thick [Carslaw and Jaeger, 1959] where:
to Equation E.6.3b, if the sample thickness is less than approxi­
mately 0.0013 m, the unexposed surface of the sample can be [E.6.3e]
expected to be relatively close to Tig at the time of ignition , and
the sample is considered to be thermally thin.

The time to ignition of a thermally thin material subjected to

incident flux above a critical incident flux is a� follows: For example, according to Equation E.6.3e, in the case of an
ignition test on a sheet of maple or oak wood, if t;g = 35 s is
measured in a piloted ignition test and if the sample thickness
[E.6.3c] is greater than approximately 0.0042 m, the unexposed surface
of the sample can be expected to be relatively close to T. at the
(T
•g
-T Q
)
tig = p el •N
time of ignition, and the sample is considet·ed to be thermally
q; thick.

Tlumnally Thick Mate1ials. Relative to the type of ignition test

described for thermally thin materials, a sample of a material of

2021 Edition
204-74 SMOKE AND HEAT VENTLNG

Table E.5.3(d) Mass Loss and Heat Release Rates of Chairs

Mass
Mass Combustible Inter- Peak, m Peak, Q
Specimen (kg) (kg) Style Frame Padding Fabric liner (g/sec) (kW)

Cl2 17.9 17.0 Traditional easy chair Wood Cotton Nylon 19.0 290"
F22 31.9 Traditional easy chair Wood Cotton (FR) Cotton 25.0 370"
F23 31.2 Traditional easy chair Wood Cotton (FR) Olefin 42.0 700h
F27 29.0 Traditional easy chair Wood Mixed Cotton 5S.O 920h
F2S 29.2 Traditional easy chair Wood Mixed Cotton 42.0 730h
C02 13.1 12.2 Traditional easy chair Wood Cotton, PU Olefin 13.2 SOOh
C03 13.6 12.7 Traditional easy chair Wood Cotton, PU Cotton 17.5 460"
COl 12.6 11.7 Traditional easy chair Wood Cotton, PU Cotton 17.5 260"
C04 12.2 11.3 Traditional easy chair Wood PU Nylon 7.5.7 1350"
Cl6
F25
T66
1 9. 1
27.S
23.0
1S.2 Traditional easy chair
Traditional easy chair
Traditional easy chair
Wood
Wood
Wood
PU
PU
PU, polyester
Nylon
Olefin
Cotton
eoprene
so.o
NA

27.7
!SOb
1990
640
F21 2S.3 Traditional easy chair Wood PU (FR) Olefin S3.0 1970
F24
C13
C14
.
2S.3
19 1
2l.S
1S.2
20.9
Traditional easy chair
Traditional easy chair
Traditional easy chair
Wood
Wood
Wood
PU (FR)
PU
PU
Cotton
Nylon
Olefin
Neoprene
Neoprene
46.0
15.0
13.7
700
230"
220"
C15 2l.S 20.9 Traditional easy chair Wood PU Olefin Neoprene 13.1 210b
T49 15.7 Easy chair Wood PU Cotton 14.3 210
F26 19.2 Thinner easy chair Wood PU (FR) Olefin 61.0 SIO
F33 39.2 Traditional loveseat Wood Mixed Cotton 75.0 940
F31 40.0 Traditional loveseat Wood PU (FR) Olefin 130.0 2S90
F32 51.5 Traditional sofa Wood PU (FR) Olefin 145.0 3120
T57
T56
54.6
11.2
Loveseat
Office chair
Wood
Wood
PU, cotton
Latex
PVC
PVC
61.9
3.1 so
l l OO

C09/T64
C07/T48
C10
.
16.6
11 4
12.1
16.2
11.2
8.6
Foam block chair
Modern ea�y chair
Pedestal chair
Wood (part)
PS foam
Rigid PU
PU, polyester
PU
PU
PU
PU
PU
19.9
3S.O
15.2
460
960
240"
foam
Cll 14.3 14.3 Foam block chair PU Nylon NA S l Ob
F29 14.0 Traditional easy chair PP foam PU Olefin 72.0 1950
F30 25.2 Traditional easy chair Rigid PU PU Olefin 41.0 1060
foam
cos 16.3 15.4 Pedestal swivel chair Molded PE PU PVC 112.0 830b
C05 7.3 7.3 Bean bag chair Polystyrene PVC 22.2 370"
C06 20.4 20.4 Frameless foam back PU Acrylic 151.0 2480b
chair
T50 16.5 Waiting room chair Metal Cotton PVC NA 10
T53 15.5 1.9 Waiting room chair Metal PU PVC 13.1 270
T54 27.3 5.S Metal frame loveseat Metal PU PVC 19.9 370
T75/f20 7.5(4) 2.6 Stackingchairs ( 4) Metal PU PVC 7.2 160
Estimated from mass loss records and assumed Wh�
a

bEstimated from doorway gas concemrations.

Time to ignition of a thermally thick material subjected to Propagation Between Separate Fuel Packages. Where the concern
incident flux above a critical incident flux is as follows: is fen- propagation between individual, separated fuel packages,
incident flux can be calculated using u·aditional radiation heat
transfer procedures [Lauten berger et al., 2016].
[E.6.3f]
The rate of radiation heat transfer from a flaming fuel pack­
age of total energy release rate, Q to a facing surface element
of an exposed fuel package can be estimated from the follow­
ing equation:
It should be noted that a particular material is not inu·insi­
cally thermally thin or thick (i.e., the characteristic of being
[E.6.3g]
thermally thin or thick is not a material characteristic or prop­
erty), but rather depends on the thickness of the particular
sample (i.e., a particular material can be implemented tn
eid1er a thermally thick or a thermally d1in configuration).

2021 Edition
 ANNEX E 204-75

Table E.6.2(a) Relation of Calorimeter-Measured Properties to E.6.4 Estimating Rate of Heat Release. As discussed in E.6.2,
Fire Analysis tests have demonsu·ated that the enet·gy feedback from a burn­
ing fuel package ranges from appt·oxirnately 25 kVI'/m2 to
Flame Fire Size 50 kWI m2. For a reasonably conservative analysis, it is recom­
Property Ignition Spread (energy) mended that test data developed with an incident flux of
50 kW/m2 be used. For a first-order approximation, it should
Rate of heat release* X X be assumed that all of the surfaces that can be simultaneously
Mass loss* X involved in burning are releasing energy at a rate equal to that
Time to ignition* X X determined by testing the material in a fire properties calorim­
Effective thermal X X eter with an incident flux of 50 kW/m2 for a free-burning mate­
propertiest rial and 75 kW/m2 to 100 kW/m2 for postflashover conditions.
Heat of combustiont X X
Heat of gasificationt X In making this estimate, it s i necessary to assume that all
Critical ignition fluxt X X surfaces that can "see" an exposing flame (or superheated gas,
Ignition temperatmet X X in the postflashover condition) are burning and releasing
energy and mass at the tested rate. If sufficient air is pt·esent,
*Property is a function of the externally applied incident flux.
the rate of heat release estimate is then calcttlated as the prod­
tDerived properties from calorimeter measurements.
uct of the exposed area and the rate of heat release per unit
area as determined in the test calot·imeter. Where test data are
taken at the incident flux of the exposing flame, the tested rate
of heat release should be used. '"There the test data are for a
different incident flux, the burning t·ate should be estimated
Table E.6.2(b) Average Maximum Heat Release Rates using the heat of gasification as expressed in Equation E.6.4a to
(kW/m2) calculate the mass burning rate per unit area.

25 kW/m2 50 kW/m2 75 kW/m2

[E.6.4a]
Exposing Exposing Exposing
Material Orientation Flux Flux Flux

PMMA Horizontal 650 900 1300

Vertical 560 720 1300
The resulting mass loss rate is then multiplied by the derived
Pine Horizontal 140 240 265
effective heat of combustion and d1e burning area exposed to
Vertical 130 170 240
the incident flux to produce the estimated rate of heat release
Sample A Horizontal 125 200 250 as follows:
Vertical 90 130 220
Sample B Horizontal 140 175 240
Vertical 60 200 330 [E.6.4b]
Sample C Horizontal 215 250
Vertical 165 170
Sample D Horizontal 70 145 145 E.6.5 Flame Spread. If it is desired to predict the growth of
Vertical 125 125 fire as it propagates over combustible surfaces, it is necessary to
estimate flame spread. The computation of flame spread rates
is an emerging technology still in an embryonic stage. Predic­
tions should be considered as order of magnitude estimates.

Flame spread is the movement of the flame front across the

2000. ----.---.------ . - - .------ . - - .------ . -
- . surface of a material that is burning (or exposed to an ignition
�
1800
� 1600 ++
tt-- �
. ,.
\•'"
':
· .
t-;:::1:::
: ::::
::: :::;:
:± ::::==
:± ::::::::
-+··..,�1- 0 kW/m2 - - - 25 kW/m 2
... -
:± :::±
:; ==
----·--·
:±::::;1::;
so kW/m2r
flame), but whose exposed surface is not yet fully involved.
Physically, flame spt·ead can be u·eated as a succession of igni­
ID
1400�--���====�===+====�==�==�==� tions resulting from the heat energy produced by the burning
m 1200��� �� ·, ��---r----r----+----r----r--�
�� portion of a material, its flame, and any other incident heat
�
Oi 1 000 -¥-- � -+ i\;---+--
-;-----f\ ---+ -- +-- ----+-----+-------l
-- energy imposed on the unburned surface. Other sources of
� 800+ �. --��-14r--�----t----1----�---1--- -�
� 600f:;7 ;�
incident energy include another bmning object, high­
+-�� '�
r-� �� � � � r- -- +--- +- � temperature gases d1at can accumulate in the upper portion of
l
Oi 400
', ,+1\--+--
17 � �
:_�� �\+----+ -- --�� �-1__----+---� an enclosed space, and the radiant heat som·ces used in a test
� 200 �+---+--�+--4�----+----+----� -�
��� --� apparatus such as the cone calorimeter or the LIFT mecha­
0 ;'
\ '-.., nism.
200 400 600 800 1 000 1200 1400 1 600
Time(sec) For analysis purposes, flame spread can be divided into the
following two categories:
FIGURE E.6.2 Typical Graphic Output of Cone Calorimeter
(1) Concurrent, or wind-aided, flame spread, which moves in
Test.
d1e same direction as the flame
(2) Lateral, or opposed, flame spread, which moves in any
other direction

2021 Edition
204-76 SMOKE AND HEAT VENTLNG

Concurrent flame spread is assisted by the incident heat flux where:

from the flame to unignited portions of the burning material . Q = rate of heat release (kW)
Lateral flame spread is not so assisted and tends to be much 2
a:g = a constant describing the speed of growth (kW/sec )

slower in progression unless an external source of heat flux is t = time (sec)

present. Concurrent flame spt-ead for thermally thick materials
can be expressed as follows: A !-squared fire can be viewed as a fire in which the rate of
heat release per unit area is constant over the entire ignited
surface, and in which the fire spreads in circttlar form with a
[E.6.5] steadily increasing radius. In such cases, the increase in the
burning area is the square of the steadily increasing fit-e radius.
Of course, other fires that do not have such a conveniently
regular fuel array and consistent burning rate might or might
not actually produce a t-squared curve. The tacit assumption is
The values for kpc and ignition temperature are calculated that tl1e t-squared approximation is close enough for reasona­
from the cone calorimeter as discussed. For this equation, the ble design decisions.
flame length, Lf is measured from the leading edge of the Figure 8.3.1 demonstrates that most fires have an incubation
burning region, and 7� is the initial temperature of the solid period during which the fire does not conform to a !-squared
material. approximation. In some cases , this incubation period might be
E.6.6 Classification of Fires for Engineering Equations. The a sedous deu-iment to the use of the !-squared approximation.
engineering equations in Chapter 8 are appropriate for steady In most instances, this is not a serious concern in large spaces
fires, limited-growth fires, and t-squared forms of continuous­ covered by this standard. It is expected that the rate of heat
growth fires. release during the incubation period will not usually be suffi­
cient to cause activation of the smoke detection system. In any
case, where such activation occurs, or where human observa­
Annex F Design Information tion results in earlier activation of the smoke-venting system, a
This annex is not a pm·t of the requit-ements of this NFPA document fortuitous safeguard will result.
but i5 includedfor infmmational pmposes only. Figure F. l (a) compares rate of heat release curves developed
F. l Growth times fOt- combustible arrays have been obtained by the aforementioned classes of !-squared fires and two test
[see Table F l(a)]. These are specified for certain storage heights. fires commonly used for test purposes. The test fires are shown
as dashed lines labeled as furniture and 6 ft storage . The
Actual tests [Yu and Stavrianidis, 19911 have demonstrated dashed curves farther from the fit-e origin show the actual rates
that it is reasonable to assume that the instantaneous heat of heat release of the test fires used in the development of the
release rate per unit height of the storage array is insensitive to residential sprinkler and a standard 6 ft high array of test
the storage height. Such behavior corresponds to the growth cartons containing foam plastic pails that also are frequently
time, lg, being inversely proportional to the square root of the used as a standard test fire.
storage height. Alternatively, it corresponds to the fire growth
coefficient, a:go being directly proportional to the storage The other set of dashed lines in Figure F.1 (a) shows these
height. For example, if the storage height is one-third the same fire etu-ves relocated to the Ot-igin of the graph. This is a
tested height, the growth time is [ 1 / (l,-3) ] 1 12 = 1.73 times the more appropriate comparison with the generic curves . It can
growth time from the test. If the storage height is three times be seen that the rate of growtll in these fires is acn1ally faster
the tested height, the growth time is ( l,-3) 112 = 0.58 times the than that prescribed for an ultra-fast fire. This is appropriate
growth time from the test. For fuel configurations that have not for a test fire designed to challenge the fire suppression system
been tested, the procedures discussed in Annex E might be being tested.
applicable. Figure F. l (b) relates the classes of !-squared fit-e gmwth
t-Squm-ed Fit-es. Over the past decade, tl10se interested in curves to a selection of actual fuel arrays.
developing generic descriptions of the rate of heat release of F.2 For consistency with Annex B and with referenced docu­
accidental open flaming fires have used a t-squm-ed approxima­ ments on the fire model LAVENT, the nomenclature for this
tion for this purpose . A !-squared fire is one in which the burn­ section differs from that of the other section in this annex. The
ing rate varies proportionally to the square of time. Frequently, definitions for the variables used in this section are provided in
!-squared fires at-e classified by tl1eir speed of growth as fast, Section B.7.
medium, or slow (and occasionally ultra-fast ) . Where these
classes are used, they are determined by the time needed for A ceiling vent design is successful to the extent that it
the fire to grow to a rate of heat release of 1000 kVl The times controls a fire-generated environment developing in a space of
for each of these classes are provided in Table F. 1 (b). For many fit-e origin accol-ding to any of a v;u-iety of possible specified
fires involving storage arrays, the time to reach 1000 kvV might criteria. For example, if tl1e likely growth rate of a fire in a
be much shorter than the 75 seconds depicted for ultra-fast particular burning commodity is known, a vent system with a
fires. large enough vent area, designed to provide for timely opening
of the vents, can be expected to lead to rates of smoke removal
The general equation is as follows: that are so large that firefighters, arriving at the fire at a speci­
fied time subsequent to fire detection, are able to attack the
fire successfully and protect commodities in adjacent spaces
[F. I]
fi-om being damaged.

2021 Edition
 ANNEX F 204-77

Table F. I (a) Continuous-Growth Frres To evaluate the success of a particular design, it is necessary
to pt·edict the development of the fire environment as a func­
Growth Time* tion of any of a number of physical characteristics that define
Fuel (sec) and might have a significant effect on the fire scenario. Exam­
ples of such characteristics include the following:
Wood pallets, stacked 0.46 m high 160-320
(6%-12% moisture) (1) The floor-to-ceiling height and area of the space and the
Wood pallets, stacked 1.52 m high 90-190 thermal pmperties of its ceiling, walls, and floor
(6%-12% moisture) (2) The type of barriers that separate the space of fire origin
Wood pallets, stacked 3.05 m high 80-120 and adjacent spaces (e.g., full walls with vertical door-like
(6%-12% moisture) vents or ceiling-mounted draft curtains)
Wood pallets, stacked 4.88 m high 75-120 (3) The material type and arrangement of the burning
(6%-12% moisture) commodities (e.g., wood pallets in plan-area arrays of 3 m
x 3 m and stacked 2 m high)
Mail bags, filled, stored 1.52 m high 190
Cartons, compartmented, stacked 4.57 m high 60 (4) The type, location, and method of deployment of devices
Paper, vertical rolls, stacked 6.10 m high 17-28 that detect the fire and actuate the opening of the vents
Cotton (also PE, PE/cot acrylic/nylon/PE), 22-43 (e.g., fusible links of specified RTI and distributed at a
garments in 3.66 m high rack specified spacing distance below the ceiling)
Ordinary combustibles rack storage, 40-270 (5) The size of the open area of the vents themselves
4.57 m-9.14 m high
The best way to predict the fire envimnment and evaluate
Paper products, densely packed in cartons, 470
the likely effectiveness of a vent design is to use a reliable math­
rack storage, 6.10 m high
ematical model that simulates the various relevant physical
PE letter u-ays, filled, stacked 1.52 m high 180
phenomena that come into play dming the fit·e scenario. Such
on cart
an analytical tool should be designed to solve well-formulated
PE trash barrels in cartons, stacked 55
mathematical problems, based on ba5ic relevant principles of
4.57 m high
physics and on fundamentally sound, well-established, empiri­
FRP shower stalls in cartons, stacked 85
cal relationships. Even in the case of a particular class of prob­
4.57 m high
lem, such as an engineering problem associated with successful
PE bottles packed in compartmented cartons, 85
vent design, there is a good deal of variation among applicable
stacked 4.57 m high
mathematical models tl1at could be developed to carry out the
PE bottles in cartons, stacked 4.57 m high 75
ta5k. Such models might differ from one another in the
PE pallets, stacked 0.91 m high 150
number and detail of the individual physical phenomena taken
PE pallets, stacked 1.83 m-2.44 m high 32-57
into account. Therefore, the list of physical characteristics that
PU mattress, single, horizontal 120
define and could have a significant effect on the fire scenario
PU insulation board, rigid foam, stacked 8
does not include outside wind conditions, which could have an
4.57 m high
important influence on the fire-generated environment. A
PS jars packed in compartmented cartons, 55
model might or might not include the effect of wind. A model
stacked 4.57 111 high
that does include the effect of wind is more difficult to develop
PS tubs nested in cartons, stacked 4.27 m high llO
and validate and is more complicated to use. Note that the
PS toy patts in cartons, stacked 4.57 m high 120
effect of wind is not taken into account in the following discus­
PS insulation board, tigid foam, stacked 7
sion of the LA V ENT model. However, by using reasonably well­
4.27 m high
accepted mathematical modeling concepts, lAVENT could be
PVC bottles packed in compartmented 9
developed to the point that it could be used to simulate this
cartons, stacked 4.57 m high
effect.
PP tubs packed in compartmented cartons, 10
stacked 4.57 111 high The discussion that follows describes a group of phenomena
PP and PE film in rolls, stacked 4.27 m high 40 that represent a physical basis for estimating the fire-generated
Distilled spirits in barrels, stacked 6.10 m high 25-40 environment and the response of heat-t·esponsive elements in
FRP: fiberglass-reinforced polyester. PE: polyethylene. PP: well-ventilated compartment fires with draft curtains and ceil­
polypropylene. PS: polystyrene. PU: polyurethane. PVC: polyvinyl ing vents activated by fusible Links, thermoplastic drop-out
chloride. panels, or other alternative means of activation or smoke detec­
*Growth times of developing fires in various combustibles, assuming tors. The phenomena include the following:
100 percent combustion efficiency.
(1) Growth of the smoke layer in the curtained area
(2) The flow dynamics ofthe buoyant fire plume
Table F.I (b) Classifications of t-Squared Fires (3) The flow of smoke through open ceiling vents
(4) The flow of smoke below draft curtains
(5) Continuation of the fire plume in the upper layer
Time to Reach
(6) Heat transfer to the ceiling surface and the thermal
1000 kW
response of the ceiling
Class (sec)
(7) The velocity and temperature distribution of plume­
Ulu·a-fast 75 driven, near-ceiling flows
Fast 150 (8) The response of near-ceiling deployed heaHesponsive
Medium 300 elements and smoke detectors
Slow 600

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204-78 SMOKE AND HEAT VENTLNG

Ultra-fast Fast Medium

r'"-, 6 ft storage
.... ..... ......._ _ __ ..
... .... --..
'

100
Time from ignition (s)
FIGURE F. I (a) Rates of Energy Release for t-Squared Frre. (Redrawn from NIST, 1987 .)

Thin plywood wardrobe � Cartons 1 5 ft high, various contents;

fastest if empty or containing
plastic foam
�I Full mail bags, 3 ft high
pallet stack
Fastest-burning
upholstered furn � �otton!IXJiyester ---,
1nnerspnng t
Ultra-fast Fast mattress Medium

100 200 300 400 500 600 700

Time from ignition (s)
FIGURE F. I (b) Relation of t-Squared Frres to Some Fire Tests.

All the phenomena in items ( 1 ) through (8) are taken into This section discusses critical physical phenomena that
account in the LAVENT model, which was developed to simu­ determine the overall environment in the curtained space up
late well-ventilated compartment fires with draft curtains and to the time of sprinkler actuation. The objective is to identify
fusible link-actuated or smoke detector-actuated ceiling vents . and describe the phenomena in a manner that captures d1e
Other models that could be developed for a similar pmpose essential features of this generic class of fire scenario and that
typically would also be expected to simulate these basic allows for a complete and general, but concise and relatively
phenomena. simple, mathematical/ computer simulation.

The space to be considered is defined by ceiling-mounted The overall building area is assumed to have near-floor inlet
draft curtains with a fire and with near-ceiling fusible link­ air openings that are large enough to maintain the inside envi­
actuated ceiling vents and sprinklers. The curtained area ronment, below any near-ceiling smoke layet·s that might fonn,
should be considered as one of several such spaces in a large at outside-ambient conditions. Figure F.2(a) depicts the
building area. Also, by specifying that the curtains be deep generic fire scenario considered. It is assumed that a two-layer
enough, they can be thought of as simulating the walls of a zone-type model adequately describes the phenomena under
single uncurtained area. investigation. The lower layer is identical to the outside ambi­
ent. The upper smoke layer thickness and properties change

2021 Edition
 ANNEX F 204-79

with time, but the layer is assumed to be uniform in space at the exu·emities of the curtained space and is deposited into
any time. Conservation of energy and mass along with the and mixed with the upper layer. The convective heat u·ansfer
perfect gas Jaw is applied to the upper layer. This leads to equa­ rate and the ceiling surface temperature on which it depends
tions that necessitate estimates of the net rate of enthalpy flow are both su·ong functiotl$ of the radial distance from the point
plus heat transfer and the net rate of mass flow to the upper of plume-ceiling impingement, and both decrease rapidly with
layer. Qualitative features of the phenomena that conu·ibute to increasing radius.
these flows and heat transfer are described briefly.
The tl1ermal response of the ceiling is driven by transient
Flow is driven through ceiling vents by cross-vent hydrostatic heat conduction. For the time period typically considered,
pressure differences. The traditional calculation uses orifice­ radial gradients in ceiling surface conditions are small enough
type flow calculation$. Bernoulli's equation is applied across a so that the conduction heat transfer is quasi-one dimensional
vent, and it is assumed that, away from and on either side of in space. Therefot·e, the thennal response of the ceiling can be
the vent, the environment is relatively quiescent. Figure F.2(b) obtained from the solution to a set of one-dimensional conduc­
depict$ the known, instantaneous, hydrostatic pressure distribu­ tion problems at a few discrete radial positions. These prob­
tion in the outside environment and throughout the depth of lems can be solved subject to net convection and radiation heat
the curtained space. These pressw·es are used to calculate the flux boundary conditions.
resulting cross-vent pressure difference, then the actual instan­
taneous mass and enthalpy flow rates through a vent. Interpolation in the radial direction between the solutions
leads to a sufficiently smooth representation of the distribu­
If and when the smoke layer boundary face drops below the tions of ceiling sw·face temperature and convective heat trans­
bottom of the draft curtains, the smoke start$ to flow out of the fer rate. The latter is integrated over the ceiling surface to
curtained space. Ais with the ceiling vents, this flow rate is deter­ obtain the net instantaneous rate of convective heat u·ansfer
mined by the cross-vent hydrostatic pressure difference. Ais losses from the ceilingjet.
depicted in Figure F.2(c), however, the pressure difference in
this case is not constant across the flow. Nonetheless, even in Convective heating and the thermal response of a near­
this configuration, the instantaneous flow rates are easily deter­ ceiling heat-responsive element, such as a fusible link or tl1er­
mined with well-known vertical-vent flow equations used tradi­ moplastic drop-out panel, are determined from the local
tionally in zone-type fire models. ceiling jet velocity and temperature. Velocity and temperature
depend on vertical distance below the ceiling and radial
The major contributors to the upper-layer flow and surface distance from the fire plume axis. If and when its fusion (activa­
heat u·ansfer are the fire and its plume. These properties are tion) temperature is reached, the device(s) operated by the
depicted in Figure F.2(d). It is assumed that the rate of energy link or other heat-responsive element is actuated.
release of the fire's combustion zone does not vary significantly
from known free-burn values that are available and assumed to For specific radial distances that are relatively near the
be specified (see Chapter 8). A known, fixed fraction of this plume, the ceiling jet is an inertially dominated flow. Its veloc­
energy is assumed to be radiated isotropically, as in the case of ity distribution, depicted in Figure F.2(e), can be estimated
a point source, from the combustion zone. The smoke layer is from the characteristics of the plume, upstream of ceiling
assumed to be relatively transparent (i.e., all radiation from the impingement. The ceiling jet temperan1re distribution, depic­
fire is incident on the bounding surfaces of tl1e comparunent). ted in Figure F.2(f) for a relative "hot" or "cool" ceiling surface,
is then estimated from the velocity (which is now known),
A plume model, selected from the several available in the upper-layer temperature, ceiling-surface temperature, and heat
literature, is used to determine the rate of mass and enthalpy flux distributiOtl$.
flow in the plume at the elevation of the smoke layer boundary.
It is assumed that all of this flow penetrates the smoke layer Annex B provides details of all equations of the LAVENT
boundaty and entet·s the upper layer. Ais the plume flow enters mathematical fire model and its associated computer program,
the upper layer, the forces of buoyancy that act to drive the developed to simulate all the phenomena described thus far.
plume toward the ceiling are reduced immediately because of LAVENT can be used to simulate and study parametrically a
the temperature increase of the upper-layer environment over wide range of relevant fire scenarios involving these phenom­
that of the lower ambient. Ais a result, the continued ascent of ena.
the plume gases is less vigorous (i.e., is at a reduced velocity) Included in B.5.5 is a summary of guidelines, assumptions,
than it would be in the absence of the layer. Also, as the plume and limitations to LAVENT. For example, as specified in that
gases continue their ascent, the temperature becomes higher subsection, LAVENT assumes that, at all times during a simula­
than it would be without the upper layer. Such higher tempera­ ted fire, the overall building space containing the curtained
tures are a result of the modified plume entrainment, which s i area of fire origin is vented to the outside (e.g., through open
now occurring in the relatively high-temperature upper layer doorw·ays). It is assumed, fi.trthennore, that the area of the
rather than in the ambient-temperature lower layer. Methods outside vents is large relative to the area of the open ceiling
of pt·edicting the characteristics of the modified upper-plume vents in the curtained area.
flow are available.
Therefore, if the total area of the outside vents is Aoun then
Having peneu·ated the smoke layer boundary, the plume (A.,/ Av) 2 is significantly larger than 1 (e.g., A.,.,/ A11 > 2). If the
continues to rise toward the ceiling of the curtained area. Ais it outside vents are in the bounding walls of the curtained space,
impinges on the ceiling surface, the plume flow turns and not in adjacent spaces, they should be located entirely below
forms a relatively high-temperature, high-velocity, turbulent­ the smoke layer boundary. Subsection B.5.5 should be refer­
ceiling jet that flows radially outward along the ceiling and enced for the details of other guidelines, assumptions, and
transfers heat to the relatively cool ceiling surface. The ceiling limitations.
jet is cooled by convection, and the ceiling material is heated
by conduction. Eventually, the now-cooled ceiling jet reaches

2021 Edition
204-80 SMOKE AND HEAT VENTLNG

If the actual size of the outside vents is not significantly involve ceiling vents. Experimental validation of the various
larger than the vent area, consideration should be given to mathematical submodel equation sets that comprise the genet-­
increasing the vent area to account for the restrictions in inlet alized IAVENT simulation is also implicit. This is the case,
air using the following multiplier: since the mathematical submodels of LAVENT, presented in
Annex B, are based on carefully reproduced correlations of
data acquired in appropriate experimental studies of the isola­

[ lt/2
[F.2]

(�J2
ted physical phenomena that, taken together, make up the
7;
combined effects of a LAVENT-simulated fit-e scenario. The
M 1+ ,""'' experimental basis and validation of the LAVENT submodels
Av_ 1u can be found in the references listed in Section B.6.
If ceiling vents are actuated by smoke detectors, the guide­
where: lines outlined in 9.2.5.4.3 should be followed. IAVENT can be
M = multiplier made to simulate this function with a very sensitive fusible link
Av = total area of open ceiling in curtained space (i.e., a link with a negligibly small RTI) and an appropriate fuse
1:mb = outside temperature temperature.
Av .,1 = total area of open vents to outside exclusive of Av
•

As specified in B.4.1, IAVENT always assumes that the flow

1'u = upper layer temperature
coefficient, C, for ceiling vents is 0.68; if the user has reason to
Annex C is a user guide for the LAVENT computer code. believe that a different value, C.,,.,., is more appropriate for a
Annex C includes a comprehensive discussion of the inputs particular vent (such as the value 0.6 suggested in 9.2.4.2), then
and calculated results of a default simulation involving a fire the input vent area for that vent should be scaled up propot-­
growing in a large pile of wood pallets (t-squared growth to a tionately (i.e., Av, input = AvC,.,er /0.68).
steady 33 MW") in a 9.1 m high curtained warehouse-type space
IAVENT calculates the time that the first sprinkler link fuses
with multiple fusible-link-actuated vents and near-ceiling­
and tl1e fire environment that develops in the cw·tained space
deployed fusible sprinkler links. Vents actuated by alternative
prior to that time. Because the model does not simulate the
means such as thermoplastic "drop-out" panels with equivalent
interaction of sprinkler sprays and fire environments, any
performance characteristics can also be modeled using
LAVENT simulation results subsequent to sprinkler waterflow
LAVENT. lnput5 to IAVENT include the following.
should be ignored.
(1) Dimensions of the Curtained Area of Fire Origin. Length,
width, and height of the curtained area of fire origin
(2) Dimensions of the Draft Curtain. Floor to bottom of the
curtain separation distance and length of the curtain (a Ceiling jet
portion of the perimeter of tl1e curtained space can Draft curtain Ceiling vents

�¥-�\�
include flooHo-ceiling walls)
(3) Properties of the Ceiling. Thickness, density, thermal conduc­
tivity, and heat capacity of the ceiling material
( 4) Characteristics of the Fire. Elevation of the base of the fire
above the floor (see 9.2.3.6); total energy release rate of
the fire, at different times during the course of the simu­
lated fit-e scenario (the computer code uses linear inter­
�
Laye terface }
.I
e --.;:: r
ir
Yt
!.._
Plume
I
Yceil Ycurt
'I
polation to approximate between these times); and the
plan area of the fire, or the total energy release rate per
FIGURE F.2(a) LAVENT Model: Frre in a Building Space
with Draft Curtains and Ceiling Vents.
unit area of the fire (in cases where the user supplies the
latter input, the computer code estimates the changing
area of the fire at any moment by using the current total
energy release rate) llp
(5) Characteristics of the Ceiling Vent-Actuating Fu.sible Links m· across
Vent-Actuating Smoke Detectors and of the Corresponding Ceil­ ceiling Pressure in
ing Vents. Horizontal distance from the fire, vertical vent curtained Ceiling vent
distance below the ceiling stu-face, RTI, and fuse tempera­
mre of the ceiling vent-actuating fusible links; also, the Upper
t/
Tu
clear open area, Av, of their associated ceiling vents layer
(6) Characteristics ofFusible Sp1"inkler Links. Horizontal distance
from the fire, vertical distance below the ceiling surface,
RTI, and fuse temperature of fusible sprinkler links
IAVENT is written in Fortran 77. The executable code oper­
ates on PC-compatible computers.
y Yce/1

I
LAVENT has had some limited expet-imental validation in
experiments with 3.34 m2 pool fires in a 37 m x 40 m x 14 m
high aircraft hangar [Walton and Notarianni, 1993; Notarianni,
19921. The hangar was equipped with near-ceiling-mounted Pressure f
brass disks of known RTI, which were used to simulate sprinkler
links or heat detector elements. The experiments did not FIGURE F.2(b) Flow Tlrrough a Ceiling Vent.

2021 Edition
 ANNEX F 204-81

Pressure in
curtained

Upper Tu
layer

Distance "Hot" ceiling, low heat transfer

below "Cool" ceiling, high heat transfer
ceiling
T

Pressure f J
FIGURE F.2(f) CeilingJet Temperature.
FIGURE F.2(c) Flow Below a Draft Curtain.

F.3 Objectives of the vent system should be defined and

� �
Convective heating
fro� re.latively hot
ce1hng Jet
T - relatively cool
c�iling material
considered. Objectives can include the following:
(1) Provide for firefighter safety and facilitate post-fire smoke
t-emoval by the fire department. The two key issues
include activation type (remote or manual removal at

.. /W/J�
lrn
"'', t(f
roof level by firefighters), and vent ratio (gross vent area
-- - to roof area). Remote activation is a preferred method;
i

::--.-�,-
however, manual activation at roof level does considerably
to relatively reduce the time a firefighter must spend on the roof
�����::��
cool floor (versus cutting a hole in the roof) and might be consid­
Tu
ered acceptable.
(2) Allow extended egress u-avel distances.
(3) Reduce smoke damage to the contents. Design features

r ��I � 0 Radiative heating

fromflames
such as ganging all vents within a sprinkler zone, and
automatically activating all of the vents within one zone
following sprinkler activation might achieve objectives 2

,I Yte - r
and 3; however, additional research is needed to validate

/� i r
r
this concept.
..
----
-- --
-- --
--�, Chapters 4 through 10 t-epresent the state of technology of
vent and draft curtain board design in the absence of sprin­
FIGURE F.2(d) The Fire, the Fire Plume, and Heat Transfer
klers. A broadly accepted equivalent design basis for using
to the Ceiling.
spt-inklers, vents, and curtain boards together for hazard
control (e.g., property protection, life safety, water usage,
obscuration) is currently not available. Designers are strongly
cautioned that use of venting with automatic sprinklers is an
area of ongoing research to determine its benefit and effect in
conjunction with automatic suppression.
This annex section provides design considerations for vent­
ing systems in sprinkler-protected areas. These design consider­
ations are based on the research that has been conducted.
.Cady Reseanh. Fot- occupancies that pt-esent a high challenge
to sprinkler systems, concern has been raised that the inclusion
Distance of automatic roof venting, draft curtains, or both can be deu-i­
below mental to the performance of automatic sprinklers. Although
ceiling there is no universally accepted conclusion from fire experi­
ence [Miller, 1980], studies on a model scale fHeskestad, 1974]
suggested the following:
(1 ) Venting delays loss of visibility.
(2) Venting results in increased fuel consumption.
(3) Depending on the location of the fire relative to the
FIGURE F.2(e) CeilingJet Velocity. vents, the water demand necessary to achieve control is
either increased or decreased over an unvented condi-

2021 Edition
204-82 SMOKE AND HEAT VENTLNG

tion. With the fire directly under the vent, water demand (a) Fire did notjump the aisles.
is decreased. With the fil-e equidistant fmm the vents, (b) The number of sprinklers operating did not exceed
water demand is increased. the design area.
(c) Fire did not spread to an end of the fuel array.
A series of test� was conducted to increase the understanding
'1\fhile the use of automatic venting and draft curtains in
of the role of automatic roof vents simultaneously employed sprinklered buildings is still under review, the designer is
with automatic sprinklers [Waterman et al., 19821. The data encouraged to use the available tools and data referenced
submitted did not provide a consensus on whether sprinkler in this document for solving pmblems peculiar to a
contml was impaired or enhanced by the presence of auto­ particular type of hazard control [Miller, 1980; Heskestad,
matic (roof) vents for the typical spacing and area. 1974; Waterman, 1982; Troup, 1994; Hinkley, et al., 1992;
Large-scale fire tests, conducted at the Factory Mutual Gustafsson, 1992; McGrattan et al., 19981.
Research fire test facility without vents, indicated that cel-tain (7) In tests where the vents were opened by fusible link, a
configurations of draft curtains can have a detrimental effect number of the vents failed to open, which was attributed
on the performance of a sprinkler system during a high­ to either the cooling effects of the control mode sprin­
challenge fire [Troup, 1994]. Two tests were conducted, one in klers on the smoke layer or direct spray cooling of tl1e
which a fire was initiated adjacent to a draft curtain, and one fusible links.
near the junction of two draft curtains. Sprinkler performance Design Considerations. As a result of the research, the follow­
in these avo tests was considered unsatisfactory because an ing guidelines are provided for the design of venting systems in
excessive number of sprinklers operated and damage signifi­ those areas of a building protected with an automatic sprinkler
cantly increased in comparison to similar tests conducted with­ system designed and installed in accordance with NFPA 13 fol­
out draft curtains. the specific occupancy hazard.
Other large-scale fire tests were conducted (Hinkley et al., (1) Draft curtains and open vents of venting systems should
19921 employing liquid fuels, small vent spacings (minimum of not adversely affect sprinklers that are capable of
4.7 m), and vents open at ignition. Hinkley reached the follow­ discharging water onto the fire, either in time of opera­
ing conclusions: tion or in the water discharge pattern.
(1) The prior opening of vents had little effect o n the opera­ (2) Vents that are open prior to sprinkler operations in a
tion of the first sprinkler. region surrounding the ignition point, within a radius of
(2) Venting substantially reduced the total number of sprin­ 1\12 sprinkler spacings, can interfere with the opening of
kler operations. sprinklers capable of delivering water to the fire. The vent
system design should consider the following:
In an independent analysis of these test�, Gustafsson [19921
noted that sprinklers near the fire source were often delayed or (a) This interference is likely to be a factor fi the total
did not operate at all. vent area is divided among many closely spaced
vents, as in the investigation by Hinkley et al.
Recent Resea·rch. The Fire Protection Research Foundation, [1992], commented on by Gustafsson [19921.
formerly known as the National Fire Protection Research Foun­ (b) If the vent spacing is several times as large as the
dation, organized large-scale tests to study the interaction of sprinkler spacing, model fil-e tests simulating a
sprinklers, roof vents, and draft curtains [McGrattan et al., 1.2 m x 1.2 m vent in a 7.6 m high building [Heskes­
1998], involving heptane spray fires and arrays of cartoned tad, 20161 showed that sprinkler operations were
plastic commodity of a standard configm-ation. The test space significantly delayed whenever ignition oCCUlTed
was ventilated by a smoke abatement system. The findings were anywhere under the area of an open vent. Other­
as follows: wise, there was little delay. This delay can be impor­
(1) In the heptane spray fires, venting had no significant tant for systems with early suppression fast response
effect on sprinkler operations, unless a fire was ignited (ESFR) sprinklers.
directly under a vent, in which case the number of spl-in­ (c) Use of high-temperature, heat-responsive actuation
kler operations decreased. mechanisms, compared to the sprinkle1-s, can miti­
(2) When a draft curtain was installed in the heptane spray gate the problem of open vents. For example, for
fires, the number of operating sprinklers increased. 74°C rated ESFR sprinklers, a minimum 180°C acti­
(3) In five tests with tl1e cartoned plastic commodity, tl1ree vation temperanu-e should be provided fo1· vents.
tests opened 20-23 sprinklers and two tests opened 5-7 Another approach would be to provide gang opera­
sprinklers, which was attributed to val-iability in the initial tion of the vents at the moment a conservative
fire growth and not to any of the variables under study. number of spl-inklers are operating.
( 4) One of these tests with ignition near a draft curtain (d) The vent system design should consider the effects
consumed much more fuel than the other tests, which of the venting system on the ceilingjet.
was attributed to fire spread under the draft curtain. (3) The location of draft curtains should be determined
(5) Effects of venting through roof vent� on smoke obscura­ considering tl1e following:
tion could not be determined because of the dominant (a) Draft curtains can delay or prevent operation and
effect of the building smoke abatement system. can interfere with the discharge of sprinklers capa­
(6) In all experiments in this study where, in some cases, ble of delivering water to the fire. In practice, sprin­
vents were open at the start of the fire, and in those klel-s capable of delivedng water to the fil-e can be
instances where the fire was located directly under a vent, considered to be those that are within 1 \12 sprinkler
sprinklers performed satisfactorily. Satisfactory sprinkler spacings of the ignition point.
performance is defined by all of the following criteria:

2021 Edition
 ANNEX F 204-83

(b) Draft curtains should be located in aisles and tiveness of the smoke vent system. Use of ganged vents
should be horizontally separated fmm combustible operated fi-om detectors or a sprinkler flow switch is a way
contents. to avoid this situation.
(c) The layout of the sprinkler protection and the
Recent Literature Review
width of the aisle below the draft curtain should be
sufficient to prevent the fire from jumping the aisle A recent papet· examines the intet-action of conu·ol mode
space. Accordingly, if a draft curtain is positioned sprinklers \vith smoke and heat vents [Beyler and Cooper,
midway between two sprinklers, the nearest possible 20011 . The paper reviews 13 experimental studies that have
ignition point should be at least 'X of one sprinkler some relevance to the claims posed for and against the
spacing away from the draft curtain. In other words, combined use of conu-ol mode sprinklers and smoke/heat
there can be no storage of combustible matet-ial vents. These studies are used to evaluate the positive and nega­
within V. of one sprinkler spacing of a draft curtain. tive claims that have been made \vith regard to the combined
Aisles fi-ee of combustible storage, centered under use of control mode sprinklers and smoke/heat vents. Three of
draft cut-rains, should be at least 1 � sprinklet- spac­ the studies investigate the use of smoke/heat vent� alone. Four
ings wide (e.g., a minimum of 15 ft aisle for 10 ft investigations include control mode sprinklers, but do not
sprinkler spacing in the direction perpendicular to include roof vents. Three of these are test series in which
the draft curtain). For situations where such an aisle perimeter vents were used in the test facility, and the fourth
width is not practical, the aisle space can be included control mode sprinklers, a partial draft curtain, and
reduced to a minimum of 8 ft, when a line of sprin­ no smoke/heat vents. Four test series included control mode
klers is provided on each side of the draft curtain, sprinklers, smoke/heat vents, and draft curtains, but utilized
4 in. to 12 in. horizontally from the face of the draft spray or pool fires that were not subject to extinguishment by
curtain. For existing sprinkler installations, these the control mode sprinklers. Four test series included conu-ol
sprinklers near the draft curtain might need to be mode sprinklers, smoke/heat vents, and draft curtains, and
staggered horizontally with respect to adjacent line used Class A fuels that were subject to extinguishment.
of sprinklers, in order to maintain the minimum
sepat-ation required by NFPA 13 and to pt-event The studies of smoke and heat venting used in conjunction
sprinkler skipping. with control mode sprinklers do not provide evidence that
(d) vVhere aisles of sufficient width cannot be main­ venting has a negative effect on control mode sprinkler
tained, full-height partitions can be used in lieu of performance.
draft curtains. Experimental studies have shown that venting does limit the
(4) The design fire's rate of heat release rate-time history spread of products of combustion by releasing them from the
should account for the operation of the sprinkler system. building within the curtained compartment of fire origin. This
(5) Determination of the smoke layer temperature should improves visibility for building occupants and firefighters who
take into account the operation of the control mode need to find the seat of the fire to complete fire extinguish­
sprinklet· system. Control mode sprinklers operate when a ment. Limiting the spread of smoke and heat also reduces
temperature-rated element fuses in each individual smoke and heat damage to the building. In the event that
control mode sprinkler head. Since in most fires only a control mode sprinklers do not operate, venting remains a
small number of conu-ol mode sprinkler heads close to valuable aid to manual control of the fire.
the seat of the fire operate, it follows that the bulk
temperature of the smoke layer and/or the ceiling jet The experimental studies have shown that early vent activa­
beyond the operating control mode sprinklers cannot be tion has no deu-imental effects on control mode sprinkler
significantly higher than the control mode sprinkler fusi­ performance and have also shown that current design practices
ble element operating temperature, due to the cooling are likely to limit the number of vents operated to one and
effect on the smoke of the operating control mode sprin­ vents may in fact not operate at all in very successful control
klers. Therefore once the first conu-ol mode sprinkler has mode sprinkler operations. Design practices should move to
operated, if calculations show the smoke layer tempera­ methods that assure early operation of vents, and vent opera­
ture to be above the control mode sprinkler fusible tion should be ganged so that the benefit of mof vents is fully
element operating temperature, the smoke layer temper­ realized. Cono-ol mode sprinkler design with vents and draft
ature should be modified to reflect this effect. A possible curtains needs to take full account of draft curtains as obsu·uc­
approach when vents are used would be to set the smoke tions.
layer temperature equal to the control mode sprinkler
fusible elements operating temperantre, this being a Following the publication of the paper by Beyler and Cooper
reasonably conservative design solution. f2001 ] , in a letter to the editor Heskestad f 2002l reviewed the
(6) The vent flow, smoke movement, and position of the conclusions of the autho1·s that: ( 1 ) venting cleady does not
smoke layer boundary should take into account the down­ have a negative effect on sprinkler performance, (2) venting
drag effect produced by operation of the sprinkler limit5 spread of combustion products, and (3) venting remains
system. a valuable aid to manual control of the fit-e in the event the
(7) The effect of control mode sprinkler cooling may limit sprinklers do not operate. He argues the view that the first two
the number of vents opening if conu-ol of the vent is only of these conclusions are performance measures that are not
by fusible link or if drop-out panels are used. If the fusible met, or well met, by current technology based on the studies
link or drop-out panel operating temperature is equal to cited by the authors. With respect to the third conclusion,
or higher than the control mode sprinkler fusible Heskestad refers to the FM Global position that venting, in­
element operating temperature, then vents outside the stalled as backup to an automatic sprinkler system that is inade­
outer ring of operating control mode sprinklers are quate or impaired, is not cost-effective because it is unlikely a
unlikely to open. This could significantly limit the effec- large loss will be averted solely due to the presence of vents.

2021 Edition
204-84 SMOKE AND HEAT VENTLNG

Annex G Informational References ISO 21927-2, Smoke and Heat Contml Systems - Pa-rt 2: Specifi­
cation for natuml smoke and heat exhaust ventilaton, 2006, Amend­
G.l Referenced Publications. The documents or portions ment 1, 2010.
thereof listed in this annex are referenced within the informa­
tional sections of this standard and are not part of the require­ ISO 21927-3, Smoke and Heat Contml Systems - Part 3: Specifi­
ments of this document unless also listed in Chapter 2 for cation fo?· powered smoke and heat exhaust ventilaton, 2006, Amend­
other reasons. There are additional lists of references at the ment 1, 2010.
ends of Annexes B, C, and D. G.l.2.4 NIST Publications. National Instintte of Standards
G.l.l NFPA Publications. National Fire Protection Associa­
and Technology, 100 Bmeau Drive, Stop 1070, Gaithersbmg,
tion, l Batterymarch Park, Quincy, MA 02169-7471 . MD 20899-1070.

NFPA 13, Standard for the Installation of Sprinkle1· Systems, 2019 DETACT-QS, DETACT-T2, GRAPH, and LAVENT programs
edition. can be downloaded from NIST at http:/ /www.bfrl.nist.gov.
vVhen downloading lAVENT, it is also necessary to download
NFPA 68, Standanl on Explosion P-rotection by Dejlagration Vent­ the file GRAPH, which is needed to display the graphics
ing, 2018 edition. pwduced by LAVENT.
NFPA 7'P, National Fire Alarm and Signaling Cod�. 2019 DETACT-QS (DETectorACTuation - Quasi-Steady) soft­
edition. ware.
NFPA 90A, Standani for the Installation of Ai1·-Conditioning and DETACT-T2 (DETector ACTuation - Time Squared) soft­
Ventilating Systems, 2021 edition. ware.
NFPA 92, Standard for Smoke Contml Systems, 2021 edition. GRAPH graphics code.
NFPA 96, Standa1·d fm· Ventilation Control and Fz1-e Pmtection of LAVENT (Link-Actuated VENTs) software.
Cmnmercial Cooking Operations, 2021 edition.
G.l.2.5 SFPE Publications. Society of Fire Protection Engi­
NFPA 287, Standm·d Test Methods for Measurement of Flammabil­ neers, 9711 Washingtonian Blvd, Suite 380, Gaithersburg, MD
ity of Materials in Cleanrooms Using a Fi1·e Pmpagation Appamtus 20878.
(FPA), 2017 edition.
SFPE Engineering Guide to Pmfonnance-Based Fi1-e Protection, 2nd
G.l.2 Other Publications. edition, 2007.
G.I.2.1 ASTM Publications. ASTM International, 100 Barr G.l.2.6 Other Publications.
Harbor Drive, P.O. Box C700, West Conshohocken, PA
19428-2959. Alpert, R. L. and E. J. Ward. "Evaluation of Unsprinklered
Fire Hazards," FireSafetyjoumal 7: 127-143, 1984.
ASTM E1321, Standard Test Method fm· Determining Material
Ignition and Flame Sp1-ead ProfJe!·ties, 2018. Babrauskas, V. "Heat Release Rates," Chaptet· 26, SFPE Hand­
book of Fire Protection Enginee1i.ng, 5th edition, Hmley et al.
ASTM E1354, Standani 'Jest Method for Heat and Visible Smoke editors, SFPE, Gaithersburg, MD, 2016.
Release Rates for MateTials and Products Using an Oxjgen Consump­
tion Calorimeter, 2017. Beyler, C., and L. Cooper. "Interaction of Sprinklers with
Smoke and Heat Vents," Fire Technology, 37: 99. 9-35, 2001.
ASTM E2058, StandaTd Test Methods for Measurement ofMaterial
Flammability Using a Fim Propagation Appamtus (FPA), 2019. Carslaw, H. S., and]. C. Jaeger. Conduction of Heat in Solids,
Oxford University Press, 1959.
G.l.2.2 BSI Publications. British Standards Institution,
389 Chiswick High Road, London W4 4AL, England. Cooper, L. Y "A Buoyant Source in the Lower of Two, Homo­
geneous, Stably Stratified Layers," 20th International Sympo­
BS 7346-5, Functional Tecommendations and calculation methods sium on Combustion, Combustion Institute, University of
for smoke and heat exhaust ventilation systems employing time­ Michigan, Ann Arbor, MI, pp. 1567-1573, 1984.
dependent design fires, 2005, reaffirmed 2012.
Cooper, L. Y "A Mathematical Model for Estimating Availa­
BS EN 12101-1, Smoke and Heat Control Systems - Part 1: Speci­ ble Safe Egress Time in Fires," Fz1-e and Matmi.als 6(3/4): 135-
fication for smoke barriers, 2006, Corrigendum, 2009. 144, 1982.
BS EN 12101-2, Smoke and Heat Cont-rol Systems - PaTt 2: Speci­ Cooper, L. Y "CeilingJet-Driven Wall Flows in Compartment
fication for natuml smoke and heat exhaust ventilaton, 2003. Fires," Combustion Science and Technology 62:285-296, 1988.
BS EN 12101-3, Smoke and Heat Control Systems - PaTt 3: Speci­ Cooper, L. Y. "Convective Heat Transfer to Ceilings Above
fication fo-r powe1-ed smoke and heat exhaust ventilatms, 2002. Enclosure Fires," 19th Symposium (International) on Combus­
tion, Combustion Institute, Haifa, Israel, pp. 933-939, 1982.
G.I.2.3 ISO Publications. International Organization for
Standardization, ISO Central Secretariat, BIBC II, Chemin de Cooper, L. Y "Estimating the Environment and the Response
Blandonnet 8, CP 401, 1214 Vernier, Geneva, Switzerland. of Sprinkler Links in Compartment Fires with Draft Curtains
and Fmible Link-Actuated Ceiling Vents," FiTe Safety journal
ISO 21927-1, Smoke and Heat Contml Systems - PaTt 1: Specifi­ 16:37-163, 1990.
cation fo-r smoke barTiers.

2021 Edition
 ANNEX G 204-85

Coopet� L. Y. "Heat Transfer from a Buoyant Plume to an Heskestad, G. "The Sprinkler Response Time Index (RTI),"
Unconfined Ceiling," journal of Heat Transfer 104:446-451 , Paper RC-81-Tp-3 pt·esented at the Technical Conference on
August 1982. Residential Sprinkler Systems, Factory Mutual Research Corp.,
Norwood, MA, April 28-29, 1981.
Cooper, L. Y., and A. Woodhouse. "The Buoyant Plume­
Driven Adiabatic Ceiling Temperature Revisited," journal of Heskestad, G., and H. F. Smith. "Investigation of a New
Heat :nansfer l08:822-826, November 1986. Sprinkler Sensitivity Approval Test: The Plunge Test," Technical
Report Serial No. 22485, RC 76-T-50, Factory Mutual Research
Cooper, L. Y., and D. W. Stroup. "Thermal Response of Corp., Norw·ood, MA, 1976.
Unconfined Ceilings Above Growing Fires and the Importance
of Convective Heat Transfer," joumal of Heat Transfer 109:172- Heskestad, G., and M. A. Delichatsios. "Environments of Fire
178, February 1987. Detectors - Phase I: Effect of Fire Size, Ceiling Height and
Material," Volume II - "Analysis," Technical Report, FMRC
Cooper, L. Y. and W. D. Davis. "Estimating the Envirorunent 22427, Factory Mutual Research Corp., Norwood, MA, July
and the Response of Sprinkler Links in Comparunent Fires 1977.
with Draft Curtains and Fusible Link-Actuated Ceiling Vents ­
Part II: User Guide for the Computer Code LAVENT," NISTIR Heskestad, G., and M. A. Delichatsios. "Environments of Fire
89-4122, National Institute of Standards and Technology, Detectors - Phase 11: Effect of Ceiling Configuration," Volume
Gaithersburg, MD, August 1989. I - "Measurements," Technical Report, FMRC 22534, Factory
Mutual Research Corp., Nonvood, MA,June 1978.
Delichatsios, M. A. "The Flow of Fire Gases Under a Beamed
Ceiling," Comlmstion andFlarne43:1-l0, 1981. Hilsemath,J. "Tables of Thermal Properties of Gases," Circu­
lar 564, National Bureau of Standards, Gaithersburg, MD,
Drysdale, D. An Int-roduction to Fire Dynamics, 3rd edition, Wiley November 1955.
and Sons, New York, 201 1 .
Hinkley, P. L. "Rates of 'Production' of Hot Gases in Roof
Emmons, H . W. "The Flow of Gases Through Vents," Venting Experiments," Fire Safety joumal 1 0:57-64, 1986.
Harvard University Home Fire Project Technical Report
No. 75, Cambt-idge, MA, 1987. Hinkley, P. L., G. 0. Hansell, N. R. Marshall, and R. Harri­
son. "Sprinklers and Vents Interaction: Experiments at Ghent,"
Emmons, H. W. "The Prediction of Fire in Buildings," 17th Colt International, U.K. Fire Research Station, Borehamwood,
Symposium (International) in Combustion, Combustion Insti­ UK, Fzr-e Sur-ve)•or; 21 (5), October 18-23, 1992.
tute, Leeds, UK, pp. 1101-1 1 1 1, 1979.
Hurley et al. editors, Table A-28, Properties of Nonmetals,
Evans, D. D. "Calculating Sprinkler Actuation Times in SFPE Handbook of Fir-e Prvtection l!.ngineering, 5th edition, pp.
Compartments," Fire Safetyjoumal 9: 147-155, 1985. 3435 to 3436, SFPE, Gaithet-sburg, MD, 2016.
Evans, D. D. "Characterizing the Thermal Response of Fusi­ Kahaner, D., National instimte of Standards and Technology,
ble Link Sprinklers," NBSIR 81-2329, National Bureau of Stand­ private communication. Kahaner, D., C. Moher, and S. Nash.
ards, Gaithersburg, MD, 1981. Numerical Methods and Softwar-e, Prentice Hall, New York, NY,
Evans, D. D., and D. '"'· Stroup. "Methods to Calculate the 1989.
Response Time of Heat and Smoke Detectors Installed Below Koslowski, C. C., and V. Motevalli. "Behavior of a 2-
Large Unobsu-ucted Ceilings," Fir·e Technology 22: 1985, 54. Dimensional Ceiling Jet Flow: A Beamed Ceiling Configura­
Gross, D. "Data Sources for Parameters Used in Predictive tion," Fire Safety Science - Proceedings of the Fomth
Modeling of Fire Growth and Smoke Spread," NBSIR 85- 3223, International Symposium, 469-480, 1994.
National Bureau of Standards, Gaithersburg MD, September l.autenberger, C., Tien, C. L., K. Y. Lee, and A. J. Stretton.
1985. "Radiation Heat Transfer," Chapter 4, SIP£ Handbook of Fir-e
Gustafsson, N. E. "Smoke Ventilation and Sprinklers - A Protection l!.ngineering, 5th edition, Hurley et al. editors,
Sprinkler Specialist's View," Seminar at the Fire Research Gaithersburg, MD, 2016.
Station, Borehamwood, U.K., May 1 1 , 1992. LAVENT software, available from National Institute of Stand­
Heskestad, G. "Engineering Relations for Fire Plumes," Fzr-e ards and Technology, Gaithersburg, MD.
Safetyjoumal7:25-32, 1984. McGrattan, K. B., A. Hamins, and D. Su-oup. "International
Heskestad, G. "Fire Plumes, Flame Height and Air Enu·ain­ Fire Sprinkler-Smoke Heat Vent-Draft Curtain Fire Test
ment," Chapter 13, SFPE Handbook of F£re Protection Engineering, Project, Large Scale Experiments and Model Development,"
5th edition, Hurley et al. editors, Gaithersburg, MD, 2016. Technical Report, National Fire Pmtection Reseat-ch Founda­
tion, Quincy, MA, September 1998.
Heskestad, G. Letter to the Editor, Fir-e 1fJChnology, 38: 207-
210, 2002. Mirier, H. E., and H.w·. Emmons. "Documentation for the
Fifth Harvard Computer Fire Code," Harvard University, Home
Heskestad, G. "Model Studies of Automatic Smoke and Heat Fire Project Technical Report 45, Cambridge, MA, 1981.
Vent Perfixmance in Sprinklered Fit-es," Technical Report
FMRC Serial No. 21933RC74-T-29, Factory Mutual Research Miller, E. E. A Position Paper to NFPA 204 Subcommittee,
Corp., Norwood, MA, September 1974. "Fire Venting of Sprinklered Properties," 1980.

Heskestad, G. "Smoke Movement and Venting," Fzr-e Safety Nelson, H. E., and E. W. Forssell. "Use of Small-Scale Test
joumal l l :77-83, 1986. Data in Hazard Analysis," Fire Safety Science - Proceedings of

2021 Edition
204-86 SMOKE AND HEAT VENTLNG

the Fourth International Symposium, International Association With Temperatures Predicted by the DETACT-QS and LAVENT
fN Fire Safety Science, 1994, pp. 971-982. Computer Models," NISTIR 4947, National Institute of Stand­
ards and Technology, Gaithersburg, MD, 1993.
Nii D., K Nitta, K Harada, and J. Yamaguchi. "Air Entrain­
ment into Mechanical Smoke Vent on Ceilings," Fire Safety Waterman, T. E., et al. Fim Venting of Sptinklet-ed Buidings,
l
Science, Proceedings of the Seventh International Symposium, IITRI Project ]08385 for Venting Research Committee, liT
pp. 729-740, 2003. Research Institute, Chicago, IL,July 1982.
Notarianni, K E. "Predicting the Response of Sprinklers and Yousef, W. W., J. D. Tarasuk, and W. J. McKeen. "Free
Detectors in Large Spaces," extended abstracts from the SFPE Convection Heat Transfet- from Upward-Facing, Isothennal,
Seminar "Large Fires: Causes and Consequences," November Horizontal Surfaces," journal of Heat 7'ransfet· 104:493-499,
16-18, 1992, Dallas, Society for Fire Protection Engineers, August 1982.
Bethesda, MD.
Yu, H. Z., and P. Stavrianidis. "The Transient Ceiling Flows of
Peacock, R. D., et al. Software Uset·'s Guide f01· the Hazard I Fi1-e Growing Rack Storage Fires," Fit·e Safety Science - Proceedings of
Hazanl Assessment Method, Version 1 . 1 , NIST Handbook 146, the 77!it·d International Symposium, Elsevier Applied Science,
Volume I, United States Department of Commet·ce, National London, 1991, pp. 281-290.
Institute of Standards and Technology, Gaithersburg, MD,
1991. Zukoski, E. E., T. Kubota, and B. Cetegen. Fi1-e Safety journal
3:107, 1981.
Purser, D. A. and J. L. McAllister. "Assessment of Hazards to
G.2 Informational References. The following documents ot­
Occupants from Smoke, Toxic Gases and Heat," Chapter 63,
SFPE Handbook of Fire Protection Engineering, 5th edition, Hurley
portions thereof are listed here as informational resources
et al. editors, SFPE, Gaithersbmg, MD, 2016. only. They are not a part of the requirements of this document.

Stroup, D. W., and D. D. Evans. "Use of Computer Fire Heskestad, G. "Venting Practices," in Fire Protection Handbook,
Models for Analyzing Thermal Detector Spacing," Fire Safety Section 18, Chapter 4, 20th edition, Cote, A. E., ed., National
Journal 14:33-45, 1988. Fire Protection Association, Quincy, MA, 2008.

Spratt, D., and A. J. M. Heselden. "Efficient Extraction of Milke, J. A. "Smoke Control by Mechanical Exhaust or Nant­
Smoke from a Thin Layer Under a Ceiling," Fire Research ral Venting," Chapter 53, SFPE Handbook of Fim .Protection Engi­
Note No. 1001, Febmary 1974. neering, 5th edition, Hurley et al. editors, SFPE, Gaithersburg,
MD, 2016.
Thomas, P. H., et al. "Investigations into the Flow of Hot
Gases in RoofVenting," Fire Research Technical Paper No. 7, Rouse, H., C. S. Yih, and H. W. Humphreys. "Gravitational
HMSO, London, 1963. Convection from a Boundary Source," Tellus 4, 201-210, 1952.

Troup,]. M. A. Lmge Scale Fit·e Tests ofRack Stored Gmup A Plas­ Yokoi, S. "Stttdy on the Prevention of Fit-e Spread Caused by
tics in Retail operation Scenarios Protected by Extra Lmge Orifice Hot Upward Current," Report No. 34, Building Research Insti­
(ELO) Sprinklers, FMRC Serial No. J.I. OX1RO.RR for Group A ntte,Japanese Ministry of Construction, November 1960.
Plastics Committee, Factory Mumal Research Corp., Norwood, G.3 References for Extracts in Informational Sections.
MA, November 1994. (Reserved)
Walton, W. D., and K E. Notat-ianni. "A Comparison of Ceil­
ingjet Temperatures Measured in an Aircraft Hangar Tests Fire

2021 Edition
 LNDEX 204-87

Index
Copyright © 2020 National Fire Protection Association. All Rights Reserved.

The copyright in this index is separate and distinct from the copyright in the document that it indexes. The Licensing provi­
sions set forth for the document are not applicable to this index. This index may not be reproduced in whole or in part by any
means without the express wTitten permission of NFPA.

-A- Construction, 7.2, A.7.2

Administration, Chap. I General, 7.1, A. 7.1

Application, 1.3 Location and Depth, 7.3

Equivalency, 1.5 Spacing, 7.4

Retroactivity, l .4
-&
Scope, 1.1
Units and Formulas, 1.6
Effective Ignition
Air Inlets, Chap. 6 Definition, 3.3.10, A.3.3.10

Air Paths, 6.7

Explanatory Material, Annex A
Construction, 6.2
-F-
Dimensions and Spacing of Air Inlets, 6.6
Fuel Array
General, 6.1, A.6.1
Definition, 3.3. l l
Installation, 6.4
Fundamentals, Chap. 4
Location, 6.3, A.6.3
Design Basis, 4.2, A.4.2
Methods of Operation, 6.5
Design Objectives, 4.1, A.4.1
Approved
Determination of Contents Hazard, 4.3
Definition, 3.2.1, A.3.2.1
Smoke Production, 4.5
Authority Having Jurisdiction (AHJ)
Base of the Fire, 4.5.1, A.4.5.1
Definition, 3.2.2, A.3.2.2
Entrainmenr, 4.5.3, A.4.5.3
-C- Virtual Origin, 4.5.3.2, A.4.5.3.2

Ceiling Jet Fire Size, 4.5.2, A.4.5.2

Definition, 3.3.1 Vent Flows, 4.6

Buoyancy and Vent Flow, 4.6.1, A.4.6.1
Clear (Air) Layer
Definition, 3.3.2 Inlet Ail; 4.6.2, A.4.6.2
Venting, 4.4
Clear Layer Interface
Definition, 3.3.3, A.3.3.3 Design O�jectives, 4.4.1
Vent Mass Flow, 4.4.3, A.4.4.3
Continuously Growing Fires
Definition, 3.3.4 Vent System Designs and Smoke Production, 4.4.2, A.4.4.2

Curtained Area
-H-
Definition, 3.3.5
Heat Detector
-D- Definition, 3.3.12

Definitions, Chap. 3
- -
I
Design Depth of the Smoke Layer
Informational References, Annex G
Definition, 3.3.6
Inspection and Maintenance, Chap. 1 2
Design Documentation, Chap. 1 3
Air Inlets, 12.5
Documentation Required, 13.1, A.13.1
Conduct and Observation of Operational Tests, 12.4
Conceptual Design Report, 13.1.2
Inspection, Maintenance, and Testing of Mechanical Smoke-
Design Brief, 13.1.1
Exhaust Systems, 12.4.3
Detailed Design Report, 13.1.3
Acceptance Testing, 12.4.3.2
Operations and Maintenance Manual, 13.1.4
Component Testing, 12.4.3.1
Design Fire
Exhaust System Maintenance, 12.4.3.4
Definition, 3.3.7
Inspection Schedule, 12.4.3.5
Design Information, Annex F
Periodic Testing, 12.4.3.3
Design Interval Time
Mechanically Opened Vents and Air Inlets, 12.4.1
Definition, 3.3.8
Thermoplastic Drop-Out Vents, 12.4.2
Draft Curtain
General, 12.1, A.12.1
Definition, 3.3.9, A.3.3.9
Ice and Snow Removal, 12.6
Draft Curtains, Chap. 7

2021 Edition
204-88 SMOKE AND HEAT VENTLNG

Inspection, Maintenance, and Acceptance Testing, 12.3 Fire Detection, D.4

Inlet Air Sources, 12.3.4 Fire Growd1, D.3
Inspection Schedules, 12.3.1 Growing Fire, D.9
Mechanically Opened Vents, 12.3.2 Increased Height of Smoke Interface, D.8
Thermoplastic Drop-Dut Vents, 12.3.3 Introduction, D.2
Requirements, 12.2, A.l2.2 Building Details, D.2.3
Inspection and Maintenance, 12.2.3 Goal, D.2.1
Mechanically Opened Vents, 12.2.1 Ignition, D.2.5
Thermoplastic Drop-Dut Vents, 12.2.2 O�jective, D.2.2
Occupancy Details, D.2.4
-L- LAVENT Analysis, D.IO
Labeled References for Annex D, D . l l
Definition, 3.2.3 Sizing of Vents, D.7
Limited-Growth Fires Steady Fire - Smoke Layer Temperature, D.6
Definition, 3.3.13 Vent Design, D.5
Listed Shall
Definition, 3.2.4, A.3.2.4 Definition, 3.2.5
Should
-M-
Definition, 3.2.6
Mechanical Smoke Exhaust System Sizing Vents, Chap. 9
Definition, 3.3.14 General, 9.1, A.9.1
Mechanical Smoke Exhaust Systems, Chap. 10 Hand Calculations, 9.2
Exhaust Rates, 10.2 Design Concepts, 9.2.2
Fire Exposure, 10.3 Mass Flow Rate in Plume, 9.2.3
General, 10.1, A.10.1 Mass Flo"' Rate Through Vents, 9.2.4, A.9.2.4
Intake Ait� 10.5 Required Vent Area and Inlet Area, 9.2.5
Number of Exhaust Inlets, 10.4, A.l0.4 Area Calculation, 9.2.5.3
Detection and Activation, 9.2.5.4
-P-
Detection Computer Programs, 9.2.5.4.4
Plastics Inlet Area, 9.2.5.2
Definition, 3.3.15
Vent Area, 9.2 .5. 1
Plugholing Vent System Designs, 9.2.1
Definition, 3.3.16
Models, 9.3
Predicting the Rate of Heat Release of Fires, Annex E Smoke
Actual Tests of Arrays Similar to That Involved, E.4
Definition, 3.3.17
Actual Tests of d1e Array Involved, E.3 Smoke Layer
Algoridm1s Derived from Tests of Arrays Having Similar Fuels
Definition, 3.3.18, A.3.3.18
and Dimensional Characteristics, E.5
Smoke Layer Boundary
Other Normalized Data, E.5.2
Definition, 3.3.19, A.3.3.19
Other Usefi.tl Data, E.5.3
Standard
Pool Fires, E.5.1
Definition, 3.2.7
Calculated Fire Description Based on Tested Properties, E.6
Background, E.6.1 -T-
Classification of Fires for Engineering Equations, E.6.6
The Design Fire, Chap. 8
Discussion of Measured Properties, E.6.2
General, 8.1, A.8.1
Estimating Rate of Heat Release, E.6.4
Growing (Continuous-Growrn) Fires, 8.3
Flame Spread, E.6.5
Steady (Limited-Growth) Fires, 8.2
Ignition, E.6.3
The Theoretical Basis ofLAVENT, Annex B
Introduction, E.!
Actuation of Vent� and Sprinklers, B.5
Sources of Data, E.2
Concludjng Remarks - A Summary of Guidelines,
Assumptions, and Limitations, B.5.5
-R-
Dependence of Open Vent Area on Fusjble-Link-Acntated
Referenced Publications, Chap. 2 Vents, B.5.4
Predicting d1e Thermal Response of d1e Fusible Links, B.5.1
-S-
The Temperature Distribution of the CeilingJet, B.5.3
Sample Problem Using Engineering Equations (Hand Calculations) The Velocity Distributions of d1e CeilingJet, B.5.2
and LAVENT, Annex D
Introduction, B.2
Abstract, D.1

2021 Edition
 LNDEX 204-89

Mass Flow and Enthalpy Flow Plus Heat Transfet; B.4 References for Annex C, C.9
Compming and the Thermal Response of d1e Ceiling, B.4.5 The Base Menu, C.5
Net Heat Transfer Flux to Ceiling's Upper Fire Properties, C.5.6
Surface, B.4.5.2 Fusible Link Properties, C.5.. 5
Net Heat Transfer Flux lO d1e Ceiling's Lower Modifying the Default Case - General, C.5.1
Surface, B.4.5.1
Outplll Parameters, C.5.4
Solving for d1e Thermal Response oflhe Ceiling
Physical Properties, C.5.3
for, B.4.5.3
Room Properties, C.5.2
Flow to the Layer from Below the Curtains, B.4.3
Solver Parameters, C.5. 7
Flow to the L'lyer from me Plume and Radiation from me
The Default Simulation, C.3
Fire, B.4.2
Flow to the Upper Layer from d1e Vents, B.4.1 The Output Variables and the Output Options, C. 7

Heat Transfer to d1e Upper Layer, B.4.4

-V-
General Properties of d1e Plume in the Upper
Layer, B.4.4.2 Vent
Properties of me Plume in the Upper Layer Definition, 3.3.20
When Yfi" < y, B.4.4.1 Vent System
Nomenclantre for Annex B, B.7 Definition, 3.3.21
Overview, B.1 Venting in Sprinklered Buildings, Chap. 1 1
References for Annex B, B.6 Amomatic Sprinkler Systems, 1 1 .2, A.11.2
The Basic Equations, B.3 Design, 1 1 . 1 , A.1 l . l
Storage Occupancies Protected by Control Mode
-U- Sprinklers, 11.3, A.11.3
User Guide for the LAVENT Computer Code, Annex C Vents, Chap. 5
An Example Simulation - The Default Case, C.8 Dimensions and Spacing of Vents, 5.4

File Status - Running the Code, C.6 Listed Vents, .5 .1, A.5.1

Getting Started, C.4 Mechanical Smoke Exhaust Systems, 5.5

Introduction - The Phenomena Simulated by LAVENT, C.2 Memods of Operation, 5.3

Ovet-view, C.1 Vent Design Constraints, 5.2

2021 Edition