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CRANE,
FLOW OF FLUIDS>
Through Valves, Fittings and Pipe
Technical Paper No. 410
By the Engineering Department
©2010 — Crane Co.
All rights reserved. This publication is fully protected by copyright and nothing that appears in it may be
reproduced, either wholly or in part, without permission.
CRANE Co. specifically excludes warranties, express or implied as to the accuracy of the data and other
information set forth in this publication and does not assume lability for any losses or damage resulting from the
Use of the materials or other application of the data discussed in this publication or in the referenced website,
including, but not limited to the calculators on www.flowotfluids.com,
CRANE Co.
400 First Stamford Place
‘Stamford, Connecticut 06902
Tel: 4-203-363-7300
www.craneco.com
Technical Paper No. 410
PRINTED IN USA.
Reprinted 10/10
ISBN 1-40052-712.0
FH-CR-TB-EN-L13-00-1010RANI
13
16.
16.
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Water Spray xed Systems fr Fre Precton. Quincy, MA: Naonal
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(Colebrook, C.F. & White, CM. (1087). The Reduction of Carying
Capaety of Pipes wth Age st. Cal Eng. Londen, (10).
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cof Roughness, Joual American Waar Works Associavon, 595), 278,
Waloc , Sharp, W.& Shield, F (1986, Precicting ilernal
Roughness in Water Mains. Miscelanacus Peper El-09-2, US Army
Engineer Waterways Exparimert Stator: Vicksburg, MS
‘Bhave, .& Gupta, R. (2007), Analysis of Water Distribution
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Coelho, PM. and Pinho, ©. 2007). Considerations About Equations
for Stoady State Faw in Natural Gas Pipelines. Journal of ne
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202-278.
Lyone, Wc, and Plea, Gs (2005) Standard Hancbook of
Potrleum and Natural Gas Engineering 2 Edtion. Burton, MA
Oxford, UK: Gull Poessional Pubishing
Mohipour, . Golehan, Hand Muay A. (2008) Pipaline Design &
Construction: A Practical Approach 2 Eaton, New Vor: ASME
Press
Shapiro, A H, (1953) Tho Oynarnies and Thermodynamics of
Compressible Fis Flow. Jahn Wiey & Sons.
(Corp and Ruble RO. (1822). Loss of Head in Vales and
Pipes of One-Hatf to Tele Inones Diameter. University of Wisconsin
Exporimanta Staion Butt, 91).
Pigot, FLLS, (1950). Pressure Losses in Tubing, Ppo, and Ftings.
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ofthe Munich Hydraute Insitute, American Society of Mechanical
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(Conte! and Optimization 4° Eaton. Beca Raton, FL CRC Press.
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{60594-2-1 Mod)-2007; pages 1-2
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Mentor Pump Selection Toot (2008). Ret ieved July 13, 2000 rom
‘Crane Pumps and Systems Website: htptnweranepumpscom!
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Flow of Fis. 2008). Revived July 13, 2008, tom Flow of Fis
Vie sta: hipsiwaw wal. com’
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‘Marks’ Standard Handbook for Mechanical Engines. 1” Edion.
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[Nelcn, WL (1988) Petoleum Retinery Enginocrng. Now York, NY:
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“Testrical Paper No. 410CRANE,
Foreword
In the 21st cantury, the global industrial base continues to
expand. Fluid handling is stil at the heart of new, more
complex processes and applications. In the 19th century,
water was the only important fluld which was conveyed from
‘one point to another in pipe. Today, almost every conceivable
fluid is handled in pipe during its production, processing,
transportation, or utilzation. in the 1950's new fluids such
as liquid metals i.e., sodium, potassium, and bismuth, as
well as liquid oxygen, nitrogen, etc., were added to the list
of more common fluids such as oil, water, gases, acids, and
liquors that were being transported in pipe atthe time. In the
‘current decade of new technologies, heattransfer fluids for
solar plants, mineral slurries, and new chemical compounds
expand the envelope of materials of construction, design,
Process pressures and temperature extremes as never
before. Transporting fluids is not the only phase of hydraulics
which warrants attention either. Hydraulic and pneumatic
mechanisms are used extensively for the precise controls of
modern aircraft, sea-going vessels, automotive equipment,
machine tools, eaiti-moving and road-building machines,
scientific laboratory equipment, and massive refineries
where precise control of fluid flow is required for plant
automation.
So extensive are the applications of hydraulic and fluid
‘mechanics that most engineering disciplines have found it
necessary to teach at least the elementary laws of fluid low,
‘To satisfy a demand for a simple and practical treatment of
the subject of flow in pipe, Crane Co. in 1938, first published
2 booklet entitied Flow of Fluids and Heat Transmission.
A revised edition on the subject of Flow of Fluids Through
Valves, Fittings, and Pipe was published in 1942 as Technical
Paper 409. In 1957, a completely new edition with an all-
‘new format was introduced as Technical Paper No. 410. In
TP. 410, Crane endeavored to present the latest available
Information on flow of fluids, in summarized form with all
auxiliary data necessary to the solution of all but the most
Unusual fluid flow problems.
‘The 1976 edition presentedaconceptualchangeregardingthe
values of Equivalent Length L/D and Resistance Coefficient
K for valves and fitings relative to the friction factor in pipes.
‘This change had a relatively minor effect on most problems
dealing with flow conditions that result in Reynolds numbers
falling in the turbulent zone. However, for flow in the laminar
zone, the change avoided a significant overstatement of
pressure drop. Consistent with this conceptual revision,
the resistance to flow through valves and filings became
‘expressed in terms of resistance coefficient K instead of
‘equivalent length L/D, and the coverage of valve and fitting
types was expanded. Further important revisions included
‘updating of steam viscosity data, orifice coefficients, and
nozzle coefficients. As in previous printings, nomographs
‘were included for the use of those engineers who preferred
graphical methods of solving some of the more simple
problems.
Inthe 2009 edition of Technical Paper 410, Crane Co. hasnow
included new flow contro! and measurement components to
the pages of this paper. Pumps and Control Valves, critical
elements of fiuid handling, are included forthe first time, as
well as Flow Meters, and several adcitianal types of valves
and fittings. We have added new illustrations and updated
the content throughout. Many of the nomographs have been
replaced with online calculators. Visit www flowoffluids.com
for the latest data
Originally, data on flow through valves and fittings were
obtained by carefully conducted experiments in the Crane
Engineering Laboratories. For this 2009 update, additionat
tests were performed within Crane to increase the number
of valves with defined resistance coefficients. In addition,
industry research was also gathered and refined to provide
the reader with the latest methods for calculating hydraulic
resistance. Resistance values for fittings were correlated
with existing industry research and, when appropriate, more
updated methods are provided in this paper, particularly
seen with the new treatment of Tees and the addition of
Wyes.
Since the last major update of TP-410, personal computers
and Web applications have become the computational
tools of choice. To meet the needs of today’s engineers we
have presented a variely of proven computational methods
to simplify fluid flow calculations for those interested in
Geveloping custom spreadsheets or computer programs.
In addition, Flow of Fluids has its own web site (www.
Flowoftluids.com) with a variaty of Web based tools to simplify
your most common fluid flow calculations,
‘The 2009 version of the Technical Paper 410 employs the
most current references and specifications dealing with
flow through vaives, fittings, pipes, pumps, control valves
and flow meters. The fluid property data found in Appendix
‘A has been updated to reflect the current research on
estimating fluid property data with references for the data
cited throughout the paper.
From 1957 until the present, there have been numerous
printings of Technical Paper No. 410. Each successive
printing is updated, as necessary, to reflect the latest flow
information available. This continual updating, we believe,
serves the best interests of the users ofthis publication, The
Flow of Fluids software and updated web site provide users
with electronic tools and a source for the latest information,
We welcome your input for Improvement
CRANE CO.
(CRANE Flow of Ful -Tectoical Paper Wo. 410CRANE]
Table of Contents
HAPTER
“Theory of Flow in Pipe
lnrocustion
Physical Ropers of Fluids
Viscosity
Weight density
Specie wlume
‘Specie gravy
Vapor pressure
Nature of Flow in Pipe Laminar and Turbulent Flow
‘Mean velaciy of fw
Reynolds number
Noncirearconcuit
General Energy Equation - Bemoul's Theorem
Measurement of Pressure
Head Lose end Pressure Drop Through Pipe
eton factor
(ebro equation
Expt approximations of Colebrook
Hazon Willams formula fr fw of water
Ect of age and uso on pipe trcton
Prnopies of Compressbe Faw in Pipe
Definition ofa perect ges
‘Spied of sound and mach puriber
‘Approaches to comprossibl ow probloms
‘Application ofthe Darcy equation fo compressie tds
Complete isothermal equation
Sinplied isothermal - gas pene equation
Other commonty used equations for eompesibe ow
in ong pipelines
‘Comparsen of equatons fr compressible town pipoknes
‘Modifications tothe isothermal flow equation
Limiting ow of gases and vapors
‘Simple compressible fons
‘Sofware solutions to compressibio flow probleme
‘Stoam - Generai Dscussion
‘Saurated eteam
Supemeated sam
chapter 2
Flow of Fluids Through Valves and Fittings
{rwrosueton
“Types a Vahes and Fitings Used in Pipe Systems
Pressure Drop Atribted to Vanes and Ftings
(Grane Pow Tests
[Description of apparatus usod
Wiatar Row tose
‘Steam fow tect
Rolaionsip of Pressure Drop te Volt of Flow
sistance Costilent K, Equivalent Lengih LD,
‘ad Flow CostisentC,
Hydraulic resistance
(Causes of head oss vales ar tings
Equivalent length
Resistance concent
Fesistance cosficlens for sipsines, valves and tings in
‘series ard parle!
Fesisiance coeficlent for geometricaly dissimilar vaves
ana iting
‘Geometrical simi ftings
“Agjsting K fr pip schedule
Fw eooticient C,
{Use of flow cosfsiont for piping and components
Flow coelicets fer ppeines, valves, ngs m eeriee
and paral
Laminar Flow Conditions
‘dusting th resistance cootclet fr Reynalés number
Contraction and Enlargement
Vahee with Reduced Seats
m
4"
4
12
12
13
13
42
13
+
+4
6
+5
6
6
7
uv
Ww
wv
18
+8
+8
+8
+8
19
8
27
26
27
27
27
27
27
28
29
28
240
20
210
20
an
22
‘CRANE Flow o Flas
Fesitance of Bends
‘Secondary How
Fosttance of bende to fow
Fesstance of mor bonds
Hysrauic Rasietance of Teas an Wyee
Converging fow
Diverging ow
Graphical representation of Ky, 2 Kay
Discharge of Fuld through Valves Ftings, a Pipe
Lge tow
Compressive tow
Types of aves
cHapTen 3
‘Regulating Flow with Contr Valves
Inweduction
‘Components
Inherent eharaceritc eve
Installed characterise une
Pressure velooty and energy profes
CCaviaton, choked flow, anc flashing
Conta Valve Sizing and Selection
‘Sizing or ncamprossi ow
Sizing for compressible tow
Conversion of C, 1K,
CHAPTER 4
Measuring Flow with Diferential Pressure Meters
Intodction
Dierental Pressure low Meters
Oiitce plate
Limits of use
Flow nozzle
Limits of use
Vertu meter
mils of use
Liquid Flow Through Orcas, Nozzles and Vertu
Mtr dferental prassure(eP)
Pressure los (NAPD)
Discharge coeticentsC,
Cries tate
Flow nozzles
\entr meters
CCompressito Flow Through Ortices, Nozzies, ana Ventut
Flow of gases and vapors
Expansbiay factors Y
Orie plates
Flow nozsies and ventur meters
Maximum fow of compressible fis in a nozzle
Fw trough shor tubes
CHAPTERS
Pumping Flulé Through Piping Systems
Ietoduetion
Centitagal Pume Operation
Cental Pump Sizing and Selection
Pump curve
NPSHa
NPSHa optimization
Vieeosty eoractions
Pump ating rules
Pump power ealetations
Pump section
Posie Displacement Pumps
‘Types of pumps
“octal Paper No. #10
pee
22
Bae
213
ea
25
25
26
20
an
a7
bao
a
a
Bt
32
22
32
32
33
a4
34
3s
36
5a
st
5A
82
53
53
63
53
53
54
a4
54
55,
56Table of Conients
(CHAPTER 6 61 APPENDIX at
Formulas For Flow 1 Physical Propertos of Fluids and Flow Charscteristies
Invodseiion 1 of Valves, Fitings, and Pipe a
Summary of Formulas 51 Inveduoton x
‘Basie conversions 62 Viscosity of Steam and Water Re
Bernoults hear 62 Viecosty of Water and Liquid Petoleum Products 43
Mean velocty of ow in pipe 62 Viscosity of Various Ligue na
Head loss and pressure oop foc ncompressbl fw in Viscosity of Gases and Vapors AS
‘right pipe 6:2 Viscosity of Ratigerant Vapors AG
Reynolds numberof flowin pipe 6-2 Physical Properties of Water a?
Lamina ftion factor 62 Spaclie Gravy - Temperature Retatonahp for Potcleum ie AB
Turbulent reton factor 62 Weight Densty and Spectic Gravy of Various Ligugs ae
Colebrook imate equation 62 Physical Proper of Gases a9
Serge expi equation 62 Volumes Composiion and Speclic Grauly ol Gaseous Fuele AD
‘Swarnec-Jan 2 Steam -Valies ol Ientopic Exponent. K a0
‘Head loss ava to tron straight pipes (Darcy) 63 Reasonable Veloctes For the Faw of Water Through Pipe m0
Hazon. Wiliame forma for fow of water 3 Reasonable Veontes ft Flow of Steam Through Pipe ao
Limitations ofthe Datey formula 63 Weight Density and Speci Volume of Gases and Vapors an
Isothermal compressive fw equations 6-3 Sstuated Steam and Saturats Waler ane
‘Simpiied Isothermal equation fr ong pps 63 Suporneated Steam M7
\Wioymouth equation (ly tule sow) 83 Suporneated Siew and Compreseed Weer x20
Panhande A equation (parvallytuouleat fs) 3 Fw Gootieen!C For Square Ecge Oriioes and Novae Aa
Panhard B equation (ly turoulet fs) 64 NetExpansion Factor, Y and Criial Presoure Fata. ae
‘AGA equation (parla turbent lon) 54 Net Expansion FacorY for Compressiie Flow ae
‘AGA equation (ly urlent flaw) 5:4 Relatve Roughness of Ppo Matorals ard Fron Factor for
‘Speed of sound and Mach nuriber 54 Compe Turbuence 26
Head loss and pressure cop trough valves and ings ‘844 Fichon Facios for Any Type of Commercial Pipa 25
Pressure drop and How o igus of ow vscaety using ow Ficion Factors for Clean Commarea Ste! Pipe 28
oetiewnt 64 Ropresontative Resistance Coetconts K for Valves and Ftings
Fosletance and tow coctcions K and ©, i Factor Table Agr
In ries and paratol 65
‘Changes in sistance coetcent Krequred 10 —
‘compansat or eferetpipo ID. 65 APPENDIX 4
Fpresontativa resistance coeficients K fr various Engineering Data Ba
valves and figs 65 inveducton cs
Discharge of ud trough valves tings and pipe: Equivalent Volume and Weight Flow Rates of Compress Fuis 2
Darcy formate 65 Equlvalonis of Absolute Dynamic Visceaty 23
Flow trough orice, nares are venturi 55 Equivaloris of Kinomate Viscosity Ba
CConto valve sizing equations 68 Kinematic and SaybotUniversat Ba
Pump perormanes equations 67 Kinematic nd Saybot Fol ba
Pump afiny rues 8:7 Kinemati, Saybot Universal, Saybat Foland Absolute Viscosty B.S
Pump power esiouitions 5:7 Equvalonis of Degroes API, Degrees Baume, Spaciie Gravy,
‘Specie gray of iquds 6:7 Weight Density and Pounds per Gaon 86
Specie gray of gases 67 Power Required for Pumping 87
ideal gas equation 67 US Comersion Tables Bo
ysrauie eas 67 Length a8
Ara 58
— Volume 8
‘CHAPTER? ” Voter Be
Examples of Flow Problems nm Mase Ba
trarecuction Mass tow rate 29
Determination of Vave Resistance nL, UO,K, and Coeiient ©, 72 alumetc lw rato be
(Check Vales, Reduced Por aves 73 Fovce Bo
Laminar Flew in Values, Fitings and Pipe 74 Pressure and iqud head 840
Prossure Crop and Veocty In Piping Sysiems 76 Energy, workhest BH0
Pipeline Flow Probiems HO Power B10
Discharge of Fluide ftom Piping Systems 742 ensity B10
Flow Through Oritee Meters 745 Temperate equivalents Bao
Aplieaion of Hysrause Radius To Flow Probleme 746 Flow of Water Trough Schedule 40 Steel Pipa ea
Conta Vas Calevlaione 748 Flowt Ar Tough Schedsle 40 Stel Pipe ae
Flow Mtr Galclstone 72) Pipa Data Carbon and Aloy Sst Staines Stee! B13
Pump Bampies 72
‘Tess and Wives 724
(CRANE Fiw of Filds Technical Paper Na. 410 vCRANE]
Nomenclature
Unless otherwise stated, all symbols used inthis book are defined as fllows:
A = cross sectional area (tt)
= cross sactional area (n*)
bhp = brake (chaft) horsepower (he)
C= How coaticient for ortices and nozzles
G, = discharge coefficient or orices and nozzles
CC), = flow coeticient fr valves or piping components
"= speed of sound in a tad 5)
= sheet heat at constant pressure (Btu “R)
ef = specific heat at constant volume (Btu/o °R)
B= imornal ameter (t)
D,. = equivalont nydraulic dametor(t)
"= intemal diameter (in)
oq = Nominal pipe or valve size (in)
"= efficiency factor (uniless)
hp = electica! horsepower (rp)
F, = liquid citcal pressure ratio factor (nitiess)
FL = spetilc heat ratio factor (unless)
F = liquid pressure recovery factor (unless)
FF, = combined piping geometry and liquid pressure recovery factor (urtless)
= piping goometry factor (unless)
£" = Darey friction factor (unless)
f= ‘ction factor in zone of complete turbulence (anitiess)
J = gravitational accoloration = 32.174 is?
H = total nead or id energy, in fet of fua (t)
= slalle pressure head at a point, in fet of fui ()
1 = specitic enthalpy of saturated qui (Btu)
hh, = specific latent nest of evaporation (Stull)
hy = speoitic enthalpy of saturated vapor (Stub)
hi = loss of static pressure head due to id flow (1)
hy = static pressure head, in inches of water (in H,0)
KC = resistance costficient (unless)
K, = Bemoul coeticint (unites)
= flow coettcient or fow factor (unites)
"= ratio of spect heat al constant preesure (c, to specific eat at constant volume (c,)
L_ = length of pie (1)
LD = equivalent iengtn ofa resistance to flow, in pipe diameters
LL, = length of pipe, in miles (m)
Mi = Mach number (aniiess)
M,_= relative molecular mass
NPSHa = Net Positive Suction Head available (ft)
NAPD = Non-Recoverable Pressure Orop (psi¢)
Thumber of moles of a gas
‘gauge prossur, in bvin® (psig)
absolute pressure, i i (psie)
absolute pressure at standard condition
uid critical pressure (psia)
© absolute tank surface pressure (osia)
absolute fluc vapor pressure (psia)
lbsolute prassure at the vana contracta(psla)
‘gauge pressure, inf (psta)
absolute pressure, in ot (peta)
fate of flow (gpm)
rate af low at lowing consstions, in 1 (cts)
rate of low at standard conditions (14.7 psia and 60°F) (Ws, sets)
rate o low a lowing conditions, in millons of cubic feet pet day (MMcta)
rate o low at standard condtions (14.7 psia and 60°F), in millons af cubic feet per day (MMseld)
tate of flow at lowing conditions, in hr (of)
‘ate of ow at standara conditions (14.7 psia and 60°F}, intr (eofh)
rate of ow at owing conditions, in min (of)
rate of ow at stendara conditions (147 psia and 60°F), in min (stn)
indvidual gas constant = Ft, (ft -(b/b, “R)
Universal gas constant = 1545.95 ft Imo! °F
FReyrolds number (unites)
hydraulic radius ()
ertieal pressure rato for compress fow
pectic gravity of kquids at spectied temperature relative to water at standard temperature (60°F) and pressure (147 psiaiunitiess)
spectic graily ofa gas relative ta ai = the rato ofthe molecular weight of the gas to that of air anitess)
vi ‘CRANE Flow of Fas Technic! Paper No. 410CRANE,
Nomenclature
Unless otherwise stated, all symbols used in this book are defined as follows:
T= absohte tomperature in degrees Rankine (A)
‘T,_= absolute temperature a standard condition = 520°R
1° = temperature, in degrees Fahrenhat CF)
1, = Saluraton lomperalure at a given pressure (F)
V_= mean vlocty of fon, nin (pm)
Y= spectre volume of ie io)
VY, = volume ct)
v' mean veloc of ow. ns tos)
¥, = sone (rertea) velocty of Row ofa pas (vs)
We = fateot tow (tm
w= tate of ow vs)
ve, = eight)
x pressure drop ratio untoss)
X= ical pressure cop rato factor wthoutftings (unless)
Xp = crlical pressure oop rato tater wth tings (unites)
Y" = natexpansion taco for compressible flaw trough oices, nozzles, vet, contol valves oppo (unas)
Z = potent! nead or elevation above reference eve (i
2, = Compressbity factor (unites)
2, = elevation at pump suction ()
2 = elevation at lankesurtace()
Grock Lottors
Alpha
a = angle (degrees)
Bota
= ratio ofsmalli large ameter i ofices and nozzles, and contractions ar enlargements pipes
eit
= iferenial between two points
Epstion
= absolute roughness or effective height of pipe wal regularities)
Ela
‘motor efficiency (unitloss)
ump otfisianay (unitiees)
\atiable speed crve (vsd) efciency (unless)
absolute (dynamic) viscosiy, in centipoise (cP)
absolute viscosity in pound mass pe: foat second (bev -s) or poundal seconds per equare foot (el - st)
absolute viscosity in lugs per foot second (sug/t-<) orn pound force seconde per sau foo lb s/t}
kinomatc viscosity, in centistokes (eS!)
kinematic viscosity (ts)
Potential energy term to accaunt for elevation changes in isthermal compressible flow equations
‘weight density o uid (ot)
mass density of tud (fer?)
‘weight densky of air at standard conelions (14,7 psia and 60°F)
angle of convergence or civergence In enlargements or contractions in pipes
Subscripts for Diameter
(defines smatier ciameter
(@) defines larger dameter
‘Subscripts for Fuld Property
(1) defines iniet (upstream) condition
(2) defines outlet (downstream) condition
‘Subscript for Average Value
(avg) defines average condition
Qs stl « ont calla aviai at menor com
(CRANE Fiow of Pics - Technical Paper No. 470 vii[crane]
CRANE |
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vill (CRANE Fw of Flugs- Technical Paper No. 410Chapter 1
Theory of Flow in Pipe
The most commonly employed method of transporting fluid
from one point to another is to force the fluid to flow through @
Piping system. Pipe of circular cross section is most frequently
Used because that shape offers not only greater structural
strength, but also greater cross sectional area per unit of wall
surface than any other shape. Unless otherwise stated, the
Word “pipe” in this book will always refer to 2 closed conduit
of circular cross section and constant internal diameter.
Only a few special problems in fluid mechanics (laminar
flow in pipe, for example) can be entirely solved by rational
mathematical means; all other problems require methods
of solution which rest, at least in part, on experimentally
determined coefficients. Many empirical formulas have
‘been proposed for the problem of flow in pipe, but these are
often extremely limited and can be applied only when the
conditions of the problem closely approach the conditions of
the experiments from which the formulas were derived,
Because of the great variety of fluids being handled in modem,
industrial processes, a single equation which can be used
{or the flow of any fluid in pipe otfers obvious advantages.
‘Such an equation is the Darcy* formula. The Darcy formula
‘can be derived rationally by means of dimensional analysis;
however, one variable in the formula (the friction factor)
must be determined experimentally. This formula has @
wide application in the field of fluid mechanics and is used
extensively throughout this paper.
“The Darcy formula is also known as the Weisbach formula or the Darey-Weisbach formula; also, as the Fanning formula,
‘sometimes modified so that the friction factor is one-fourth the Darcy friction factor.
(CRANE Flew of Fluide Tecnica! Paper No. 410 1-1CRANE,
Physical Properties of Fluids
‘The solution of any flow problem requires a knowledge of
the physical properties of the fluid being handled. Accurate
values for the properties affecting the flow of fluids (namely,
viscosity and weight density) have been established by
‘many authorities forall commonly used fluids and many of
these data are presented in the various tables and charts in
Appendix A
Viscosity: Viscosity expresses the readiness with which a
fluid flows when it is acted upon by an external force. The
Coefficient of absolute viscosity of, simply, the absolute
viscosity of a fluid, is a measure of Ils resistance to internal
deformation or shear. Molasses is a highly viscous fluid;
water is comparatively much less viscous; and the viscosity
of gases is quite small compared to that of water.
Although most fluids are predictable in their viscosity, in
some, the viscosity depends upon the previous working of
the fluid. Printer’s ink, wood pulp slurries, and catsup are
‘examples of fluids possessing such thixotropic properties of
viscosity
Considerable confusion exists concerning the units used to
express viscosity: therefore, proper units must be employed
whenever substituting values of viscosity into formulas.
In the metric system, the unit of absolute viscosity is the
polse which is equal to 100 centipoise. The poise has the
dimensions of dyne seconds per square centimeter or
of grams per centimeter second. It is believed that less
confusion concerning units will prevail if the centipoise is
used exclusively as the unit of viscosity. For this reason, and
‘since most handbooks and tables follow the same procedure,
all viscosity data in this paper are expressed in centipoise,
‘The English units commonly employed are “slugs per foot
second” oF "pound fore seconds per square foot; however,
“pound mass per foot second" or “poundal seconds por
square foot may also be encounteree. The viscosity of water
ata tomperature of 68°F s
(0.01 poise
= 1 eentipcise* = } 0.01 gram por cm second
0.01 ayne Second per sq cm
1p, = (0.000 672 pound mass per foot second
"= (0.000 672 poundal second per square foot
1, =)0000 0209 sug per fot second
“©.
.000 0209 pound force second per square ft
“Actually the viscosity of water at 68°F is 1.005 centipoise.
1-2
‘CRANE Flow of Fids Technical Paper No. 10
Kinematic viscosity is the ratio of the absolute viscosity
to the mass density. In the metric system, the unit of
kinematic viscosity is the stoke, The stoke has dimensions
of square centimeters per second and is equivalent to 100
centistokes. Equation 1-1
b_(centipoise) “
© (eontistokes) = grams per cubism) ""S.,
By definition, the specific gravity, Sin the foregoing formulais
based upon water at a temperature of 4°C (39.2°F), whereas
specific gravity used throughout this paper is based upon
water at 60°F. In the English system, kinematic viscosity has
dimensions of square feet per second.
Factors for conversion between metric and English system
Units of absolute and kinematic viscosity are given on page
B-3 of Appendix B.
The measurement of the absolute viscosity of fluids
(especially gases and vapors) requires elaborate equipment
and considerable experimental skil. On the other hand, a
rather simple instrument can be used for measuring the
kinematic viscosity of oils and other viscous liquids. The
instrument adopted as a standard is the Saybolt Universal
Viscometer. in measuring kinematic viscosity with this
instrument, the time required for a small volume of liquid
to flow through an orifice is determined; consequently, the
“Sayboit viscosity” of the liquid is given in seconds. For very
viscous liquids, the Saybolt Furol instrument is used.
Other viscometers, somewhat similar to the Saybolt but not
Used to any extent, is the Engler, the Redwood Admiralty, and
the Redwood. The relationship between Saybolt viscosity
‘and kinematic viscosity is shown on page B-4; equivalents.
‘of kinematic, Saybolt Universal, Saybolt Furol, and absolute
viscosity can be obtained from the chart on page B-5,
The viscosities of some of the most common fluids are
given on pages A to A. It willbe noted that, witha rise in
temperature, the viscosity of liquids decreases, whereas the
viscosity of gases increases. The effect of pressure on the
viscosity of liquids and ideal gases is so small that itis of
io practical interest in most flow problems. Conversely, the
viscosity of saturated, or only slightly superheated, vapors
is appreciably altered by pressure changes, as indicated
‘on page A2 showing the viscosity of steam. Unfortunately,
the data on vapors are incomplete and, in some cases,
contradictory. Therefore, itis expedient when dealing with
vapors other than steam to neglect the effect ot prossure
because of the lack of adequate data
(Chapter 1 Theory of Flow in Pipe