Intro pages 11/28/00 2:31 PM Page 5

Heater Selection
Matrix

Customer Assistance
Heating: Solids
Typical
Heater Application Description Sheath Maximum Watt Maximum Operating Catalog
Type Materials Densities Temperatures Page
W/in2 (W/cm2) °F (°C)

Band Clamped to cylindrical surfaces, i.e. extrusion barrels Aluminized Steel

and nozzles. mica insulation *20–55① (3–8.5) 900 (480) 23
Stainless Steel with
mica insulation *20–55① (3–8.5) 1000 (540) 23
Stainless Steel with
mineral insulation *30–200① (4.6–31) 1400 (760) 13
Zinc Steel with
mica insulation *20–55① (3–8.5) 900 (480) 23
Cable Can be formed to heat flat or curved surfaces, or wound Inconel® or
around the object being heated. Typical applications Stainless Steel 30 (4.6) 1200 (650) 57
include platen heating and plastic injection molding
nozzles.
Cartridge Inserted into a close fit hole, i.e. platens, dies and molds. Incoloy® **up to 600➁ (93) 1600 (870) 75
Stainless Steel **up to 600➁ (93) 1000 (540) 75
Cast-in Integrating a tubular or cable heating element into a Aluminum 60 (9.3) 700 (370) 135
casting to form a heated part. Commonly used to reduce
the total number of equipment parts.
Ceramic Form the heaters into an oversized chamber to surround Molded Ceramic Fiber 30 (4.6) 2200 (1205) 141
Fiber the object being heated. Using radiant and convection
heat transfer, ceramic fiber heaters are used as ovens
and furnaces.
Flexible Bonded or otherwise fastened to the part. Commonly Kapton® 20 (3.1) 390 (200) 189
used to heat irregular surfaces and shapes, or applica- Mica 50 (7.8) 1100 (595) 193
tions requiring distributed wattage or limited space. Neoprene 2 (0.3) 250 (120) 191
Silicone Rubber 10 (1.6) 500 (260) 169
Multicell Loosely inserted into a platen hole for radiant heating. Inconel® **60➁ (9.3) 2250 (1230) 195
Can also be used in any static or dynamic non-contact Incoloy®
application as a radiant heat source. Commonly used Stainless Steel
for extreme high temperature applications, i.e. glass bend-
ing and tempering or super plastic forming and diffusion
bonding of titanium and other exotic aerospace alloys.
Radiant Used in any static or dynamic, non-contact application Incoloy® Tubular 40 (6.2) 1500 (815) 217
where conduction or convection heating isn’t practical. Molded Ceramic
Commonly used in laminating processes, thermoforming Fiber 30 (4.6) 2000 (1095) 211
and paint drying. Note: quartz tubes supply quick heat Quartz Tube 45 (7) 1600 (870) 225
up and cool down. Stainless Steel
Emitter Strip 30 (4.6) 1300 (700) 224
Strip Bolted or clamped to surface of, i.e. dies, molds, ovens. Aluminized Steel with
Often used for freeze and moisture protection. refractory insulation +50➂ (7.7) 1200 (650) 241
Stainless Steel with
mica insulation +35➂ (5.4) 1000 (540) 233
Stainless Steel with
mineral insulation +100➂ (15.5) 1400 (760) 229
Zinc-coated Steel
with mica insulation +25➂ (3.8) 900 (480) 233
Tubular Clamped to the object to be heated, usually exterior Flat: Incoloy® 40 (6.2) 1400 (760) 299
surfaces of tanks or other process vessels or fitted into Stainless Steel 40 (6.2) 1200 (650) 299
milled grooves in a platen. Round: Incoloy® 40 (6.2) 1600 (870) 273
Stainless Steel 40 (6.2) 1200 (650) 273

①Figures shown are typical watt density ranges. Band size and thermal characteristics of the material heated will determine recommended watt density.
➁Applications and heater constructions differ. Consult the application section in this catalog for more detailed application information.
➂These are typical maximum watt densities. Heater clamping, environmental conditions and material being heated will determine recommended watt densities.
Kapton® is a registered trademark of E. I. du Pont de Nemours & Company. Incoloy® and Inconel® are registered trademarks of the Special Metals Corporation.

5
Intro pages 11/28/00 2:31 PM Page 6

Heater Selection
Matrix
Heating: Liquids/Surface Heating and Immersion
Typical
Heater Application Description Sheath Maximum Watt Maximum Operating Catalog
Type Materials Densities Temperatures Page
W/in2 (W/cm2) °F (°C)

Band Clamped to cylindrical surfaces, most commonly used to Aluminized Steel

heat liquids flowing through pipes as freeze protection. mica insulation *20–55a (3–8.5) 900 (480) 23
Stainless Steel with
mica insulation *20–55➃ (3–8.5) 1000 (540) 23
Stainless Steel with
mineral insulation *30–200➃ (4.6–31) 1400 (760) 13
Zinc Steel with
mica insulation *20–55➃ (3–8.5) 900 (480) 23
Cable Wrapped or wound around pipe or vessel containing a Inconel® or
liquid, or used directly as an immersion heater. Often used Stainless Steel 30 (4.6) 1200 (650) 57
in applications with space limitations, i.e. photo process-
ing equipment, scientific instruments and heat tracing.
Cartridge Used as an immersion heater placed either directly in the Incoloy® up to 300 (46.5) 212 (100) 111
liquid, or in a protective well. Recommeded for immersion in water in water
in water or 90+ percent water soluble solutions.
Cast-in Cast with passages through which liquids pass and are Aluminum 60 (9.3) 700 (370) 135
heated, functioning as a circulation heater or clamped
around a barrel or pipe. Most often used where long life,
resistance to contamination and reliability are critical.
Ceramic Assemble heaters into a chamber which surrounds the Molded Ceramic Fiber 30 (4.6) 2200 (1205) 141
Fiber tank, vessel, crucible or bath. Radiant and convection
heat transfer heat the load.
Flexible Applied to the surface of a pipe or vessel containing Kapton® 20 (3.1) 390 (200) 189
a liquid. Well suited for curved surfaces and irregular Neoprene 2 (0.3) 250 (120) 191
shaped objects. Frequently used for freeze protection. Silicone Rubber 10 (1.6) 500 (260) 169
Strip Bolted or clamped to the wall of a tank or vessel. Used Aluminized Steel with
in food warming and other applications offering a flat refractory insulation +50➂ (7.7) 1200 (650) 241
mounting surface. Stainless Steel with
mica insulation +30➂ (4.6) 1000 (540) 233
Stainless Steel with
mineral insulation +100➂ (15.5) 1400 (760) 229
Zinc Steel with
mica insulation +25➂ (3.8) 900 (480) 233
Tubular Immersed directly in the liquid being heated. Most Flat: Incoloy® 60 (9.3) 1400 (760) 299
commonly used when high kilowatts are required. Stainless Steel 60 (9.3) 1200 (650) 299
Multiple style mounting adaptors, such as flanges and Round: Copper 60 (9.3) 350 (180) 273
NPT fittings, provide excellent pressure boundaries. Incoloy® 60 (9.3) 1600 (870) 273
Stainless Steel 60 (9.3) 1200 (650) 273
Steel 60 (9.3) 750 (400) 273

Heating: Gases
Typical
Heater Application Description Sheath Maximum Watt Maximum Operating Catalog
Type Materials Densities Temperatures Page
W/in2 (W/cm2) °F (°C)

Cable Cable heaters are sinuated or wound into coils which can Inconel® or
be inserted into a pipe or vessel to heat flowing air or Stainless Steel 30 (4.6) 1200 (650) 57
gases. Cable heaters readily lend themselves to appli-
cations where space is restricted.
Cartridge Mounted in pipes or vessels through which gases pass. Incoloy® or Consult
Can be placed in protection tubes, making access and Stainless Steel 400 (62) Watlow 75
wiring easier.

CONTINUED
➂These are typical maximum watt densities. Heater clamping, environmental conditions and material being heated will determine recommended watt densities.
➃Per application

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Intro pages 11/28/00 2:31 PM Page 7

Heater Selection
Matrix

Customer Assistance
Heating: Gases Continued

Typical
Heater Application Description Sheath Maximum Watt Maximum Operating Catalog
Type Materials Densities Temperatures Page
W/in2 (W/cm2) °F (°C)
Ceramic Used to construct chambers and furnaces through which Molded Ceramic Fiber 30 (4.6) 2200 (1205) 141
Fiber gases are passed. Heaters function as high temperature
radiant heaters surrounding transfer pipes or other
special vessels.
Flexible Applied to the surface of a pipe or vessel containing gases. Kapton® 5 (0.8) 390 (200) 189
Well suited for curved surfaces and irregular shaped Neoprene 2 (0.3) 250 (120) 191
objects. Excellent for use in enclosures. Silicone Rubber 5 (0.8) 500 (260) 169
Multicell Multiple elements placed in a duct or vessel through Inconel® *60d (9.3) 2100 (1150) 195
which gases pass. Designs also available to heat pass Incoloy®
tube externally to isolate gas from the element. Excellent
for use in high temperature/high pressure applications.
Strip Generally modified with the addition of fins to increase Aluminized Steel with
surface area. Commonly used for air heating, drying refractory insulation ^60e (9.3) 1200 (650) 241
ovens and space heaters. Stainless Steel with
mica insulation ^20e (3) 1000 (540) 233
Stainless Steel with
mineral insulation ^100c (15.5) 1400 (760) 229
Zinc-coated Steel
with mica insulation ^20e (3) 900 (480) 233
Tubular Multiple elements mounted in an array and placed in a Flat: Incoloy® 30 (4.6) 1400 (760) 299
duct or vessel through which gases pass. Flat tubular Stainless Steel 30 (4.6) 1200 (650) 299
elements can be modified with the addition of fins to Round: Incoloy® 30 (4.6) 1600 (870) 273
increase surface area. Inconel® 30 (4.6) 1800 (980)

➃ Per application
➄ These are typical maximum watt densities. Ambient temperature and flow will determine recommended watt density.

Heating: Vacuums
Typical
Heater Application Description Sheath Maximum Watt Maximum Operating Catalog
Type Materials Densities Temperatures Page
W/in2 (W/cm2) °F (°C)

Band Clamped to cylindrical surfaces. Sealed heater Stainless Steel with

construction with special lead end seal. mineral insulation 30-100 (4.6-15.5)a 1400 (760) 23
Cable Wound into a coil or sinuated and mounted in a vacuum Inconel® or
vessel for radiant energy transfer. Stainless Steel 30 (4.6) 1200 (650) 57
Cartridge Mounted in a vacuum vessel for radiant energy transfer. Incoloy® *up to 35➃ (5.4) 1600 (870) 75
Stainless Steel *up to 35➃ (5.4) 1000 (540) 75
Cast-in Construction of a vacuum vessel with cast-in heaters so Aluminum 60 (9.3) 700 (370) 135
that interior surface acts as a radiant heater. Possible
zoned interior surface.
Ceramic Surround the exterior of a vacuum vessel, using radiant Molded Ceramic Fiber 30 (4.6) 2200 (1205) 141
Fiber energy for heat transfer.
Flexible Applied to the exterior surface of a pipe or vessel. Kapton® 7 (1.1) 390 (200) 189
Well suited for curved surfaces and irregular shaped Neoprene 2 (0.3) 250 (120) 191
objects. Note: Kapton is the only flexible heater type Silicone Rubber 10 (1.6) 500 (260) 169
recommended for use in the vacuum.
Multicell Mounted in a vacuum vessel for radiant energy transfer. Inconel® *60➃ (9.3) 2250 (1230) 195
Stainless Steel➄
Radiant Mounted in a vacuum vessel for radiant energy transfer. Stainless Steel 30 (4.6) 1300 (700) 215
Tubular Mounted in a vacuum vessel for radiant energy transfer. Flat: Incoloy® 30 (4.6) 1400 (760) 299
Stainless Steel 30 (4.6) 1200 (650) 299
Round: Incoloy® 30 (4.6) 1600 (870) 299
Inconel® 30 (4.6) 1800 (980)

➃ Per application
➄ Non-magnetic stainless steel available.

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W A T L O W

Reference Data
Formulas, Conversions
and Engineering
Constants

Volts E Amperes
WR R
Volts = Watts X Ohms Amperes = Volts
W W Ohms
I

Reference Data
Volts = Watts R
Amperes Amperes = Watts
Volts
Volts = Amperes X Ohms
IR E I
(Volts) (Amps)
W
E
Amperes = Watts
Ohms

(Ohms) (Watts)
E EI
Ohms
Ohms = Volts
I R W Watts
Watts = Volts
2

Amperes Ohms
W I2R
Volts2 Watts = Amperes2 X Ohms
Ohms = I2
Watts E2
2 2
E2 Watts = Volts X Amperes
Ohms = Watts W R
Amperes2

Wattage varies directly as ratio of

voltages squared

()
W2 = W1 X E2
E1
2

Total Watts
3 Phase Amperes =
Volts X 1.732

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Reference Data
Formulas, Typical 3 Phase Wiring Diagrams and Equations for Resistive Heaters
Conversions and Definitions
Engineering For Both Wye and Delta Wye and Delta Equivalents
Constants (Balanced Loads) WDELTA = 3 WWYE
VP = Phase Voltage WODELTA = 2⁄3 WDELTA
VL = Line Voltage WOWYE = 1⁄2 WWYE
IP = Phase Current
IL = Line Current
R = R1 = R2 = R3 =
= Resistance of each branch
W = Wattage

3-Phase Wye (Balanced Load) 3-Phase Open Wye (No Neutral)

IPO
IP
R2 VP R2 VPO

VL VL
R1 R1
R3

ILO
IL

Equations For Wye Only Equations For Open Wye Only

(No Neutral)
IP = IL
VP = VL/1.73 IPO = ILO
WWYE = VL2/R = 3(VP2)/R VPO = VL/2
WWYE = 1.73 VLIL W0WYE = 1/2 (VL2/R)
W0WYE = 2 (VPO2/R)

3-Phase Delta (Balanced Load) 3-Phase Open Delta

IL I L01

I P01
R1 R2 R1
VP VP
IP
VL I P03 VL

R3 R3
I L02
IL I L03

Equations For Delta Only Equations For Open Delta Only

IP = IL/1.73 VP = VL
VP = VL IPO1 = IPO3 = ILO2
WDELTA = 3 (VL2)/R ILO3 = 1.73 IPO1
WDELTA = 1.73 VLIL W0DELTA = 2 (VL2/R)

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W A T L O W

Reference Data
➀
Quick Estimates of Kilowatt-Hours to Heat Steel
Wattage Temperature Rise °F
Amount
Requirements of Steel 50° 100° 200° 300° 400° 500° 600°
The following tables can be used (lb.) Kilowatts to Heat in One Hour
to make quick estimates of wattage
25 0.06 0.12 0.25 0.37 0.50 0.65 0.75
requirements. 50 0.12 0.25 0.50 0.75 1.00 1.25 1.50
100 0.25 0.50 1.00 1.50 2.00 2.50 3.00
150 0.37 0.75 1.50 2.25 3.00 3.75 4.50
200 0.50 1.00 2.00 3.00 4.00 5.00 6.00
250 0.65 1.25 2.50 3.75 5.00 6.25 7.50
300 0.75 1.50 3.00 4.50 6.00 7.50 9.00
400 1.00 2.00 4.00 6.00 8.00 10.00 12.00

Reference Data
500 1.25 2.50 5.00 7.50 10.00 12.50 15.00
600 1.50 3.00 6.00 9.00 12.00 15.00 18.00
700 1.75 3.50 7.00 10.50 14.00 17.50 21.00
800 2.00 4.00 8.00 12.00 16.00 20.00 24.00
900 2.25 4.50 9.00 13.50 18.00 22.50 27.00
1000 2.50 5.00 10.00 15.00 20.00 25.00 30.00
➀ Read across in table from nearest amount Includes a 20% safety factor to compensate for
in pounds of steel to desired temperature rise high heat losses and/or low power voltage.
column and note kilowatts to heat in one hour. For Steel: Use table or metric equation.
kW = Kilograms X Temperature Rise (°C)
5040 X Heat-up Time (hrs.)
Kilowatt-Hours to Heat Oil ➁

Amount of Oil Temperature Rise °F

Cubic
Gallons 50° 100° 200° 300° 400° 500°
Feet
0.5 3.74 0.3 0.5 1 2 2 3
1.0 7.48 0.5 1.0 2 3 4 6
2.0 14.96 1.0 1.0 2 4 6 11
3.0 22.25 2.0 3.0 6 9 12 16
4.0 29.9 2.0 4.0 8 12 16 22
5.0 37.4 3.0 4.0 9 15 20 25
10.0 74.8 5.0 9.0 18 29 40 52
15.0 112.5 7.0 14.0 28 44 60 77
20.0 149.6 9.0 18.0 37 58 80 102
25.0 187 11.0 22.0 46 72 100 127
30.0 222.5 13.0 27.0 56 86 120 151
35.0 252 16.0 31.0 65 100 139 176
40.0 299 18.0 36.0 74 115 158 201
45.0 336.5 20.0 40.0 84 129 178 226
50.0 374 22.0 45.0 93 144 197 252
55.0 412 25.0 49.0 102 158 217 276
60.0 449 27.0 54.0 112 172 236 302
65.0 486 29.0 58.0 121 186 255 326
70.0 524 32.0 62.0 130 200 275 350
75.0 562 34.0 67.0 140 215 294 375
➁ Read across in table from nearest amount Add 5% for uninsulated tanks.
in gallons of liquids to desired temperature rise For Oil:
column and note kilowatts to heat in one hour. Use equation or table.
kW = Gallons X Temperature Rise (°F)
Includes a 20% safety factor to compensate for
800 X Heat-up time (hrs.)
high heat losses and/or low power voltage.
OR
For Steel: Use table or metric equation.
kW = Liters X Temperature Rise (°C)
kW = Kilograms X Temperature Rise (°C)
1680 X Heat-up time (hrs.)
5040 X Heat-up Time (hrs.)

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ref data text 11/22/00 10:36 AM Page 430

Reference Data
➀
Quick Estimates of Kilowatt-Hours to Heat Water
Wattage Amount of Liquid Temperature Rise °F
Requirements ft3 Gallons
20° 40° 60° 80° 100° 120° 140°
Kilowatts to Heat in One Hour
0.66 5 0.3 0.5 0.8 1.1 1.3 1.6 1.9
1.3 10 0.5 1.1 1.6 2.1 2.7 3.2 3.7
2.0 13 0.8 1.6 2.4 3.2 4.0 4.8 5.6
2.7 20 1.1 2.2 3.2 4.3 5.3 6.4 7.5
3.3 25 1.3 2.7 4.0 5.3 6.7 8.0 9.3
➀ Read across in table from nearest amount in 4.0 30 1.6 3.2 4.8 6.4 8.0 9.6 12.0
gallons of liquid to desired temperature rise 5.3 40 2.1 4.0 6.4 8.5 11.0 13.0 15.0
column and note kilowatts to heat in one hour. 6.7 50 2.7 5.4 8.0 10.7 13.0 16.0 19.0
8.0 60 3.3 6.4 9.6 12.8 16.0 19.0 22.0
For Heating Flowing Water:
9.4 70 3.7 7.5 11.2 15.0 19.0 22.0 26.0
kW = GPM X Temperature Rise (°F) X 0.16 10.7 80 4.3 8.5 13.0 17.0 21.0 26.0 30.0
OR 12.0 90 5.0 10.0 14.5 19.0 24.0 29.0 34.0
13.4 100 5.5 11.0 16.0 21.0 27.0 32.0 37.0
kW = Liters/min. X Temperature Rise (°C) X 0.076
16.7 125 7.0 13.0 20.0 27.0 33.0 40.0 47.0
For Heating Water in Tanks: Use equation or table. 20.0 150 8.0 16.0 24.0 32.0 40.0 48.0 56.0
kW = Gallons X Temperature Rise (°F) 23.4 175 9.0 18.0 28.0 37.0 47.0 56.0 65.0
375 X Heat-up Time (hrs) 26.7 200 11.0 21.0 32.0 43.0 53.0 64.0 75.0
33.7 250 13.0 27.0 40.0 53.0 67.0 80.0 93.0
OR
40.0 300 16.0 32.0 47.0 64.0 80.0 96.0 112.0
kW = Liters X Temperature Rise (°C) 53.4 400 21.0 43.0 64.0 85.0 107.0 128.0 149.0
790 X Heat-up Time (hrs) 66.8 500 27.0 53.0 80.0 107.0 133.0 160.0 187.0

Kilowatt-Hours to Heat Air

Amt.
Temperature Rise °F
of
Air
CFM 50° 100° 150° 200° 250° 300° 350° 400° 450° 500° 600°

100 1.7 3.3 5.0 6.7 8.3 10.0 11.7 13.3 15.0 16.7 20.0
200 3.3 6.7 10.0 13.3 16.7 20.0 23.3 26.7 30.0 33.3 40.0
300 5.0 10.0 15.0 20.0 25.0 30.0 35.0 40.0 45.0 50.0 60.0
400 6.7 13.3 20.0 26.7 33.3 40.0 46.7 53.3 60.0 66.7 80.0
500 8.3 16.7 25.0 33.3 41.7 50.0 58.3 66.7 75.0 83.3 100.0
600 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0 100.0 120.0
700 11.7 23.3 35.0 46.7 58.3 70.0 81.7 93.3 105.0 116.7 140.0
800 13.3 26.7 40.0 53.3 66.7 80.0 93.3 106.7 120.0 133.3 160.0
900 15.0 30.0 45.0 60.0 75.0 90.0 105.0 120.0 135.0 150.0 180.0
Use the maximum anticipated airflow. 1000 16.7 33.3 50.0 66.7 83.3 100.0 116.7 133.3 150.0 166.7 200.0
This equation assumes insulated duct
1100 18.3 36.7 55.0 73.3 91.7 110.0 128.3 146.7 165.0 183.3 220.0
(negligible heat loss). 70°F inlet air and
14.7 psia. 1200 20.0 40.0 60.0 80.0 100.0 120.0 140.0 160.0 180.0 200.0 240.0
For Air:
Use equation or table.
kW = CFM➀ X Temperature Rise (°F)
3000
OR
kW = Cubic Meters/Min➀ X Temperature Rise (°C)
47
For Compressed Air:
kW = CFM➁ x Density➁ X Temperature Rise (°F)
228
OR
kW = Cubic Meters/Min➁ X Temperature Rise (°C) X Density (kg/m3)➁
57.5

➀ Measured at normal temperature and pressure.

➁ Measured at heater system inlet temperature and pressure.
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W A T L O W

Reference Data
Formulas, Commonly Used Geometric Areas And Volumes
Conversions and Areas and Dimensions of Plane Figures
The following illustrations show the areas of plane figures, the surfaces of solids,
Engineering and the volumes of solids.
Constants
Square,
Rectangle,
Parallelogram Circular Ring
a d A = area.
A = area. r
R D A = (R2 - r2)
A = ab
b = 0.7854 (D2 - d2)
Note that dimension
a is measured at right
angles to line b.

Reference Data
Triangle Cube or
h
Square Prism
A = area. b
V = volume
A = bh c
2 a A = area of surface.
b
V = abc
A = 2ab + 2ac + 2bc

a Cylinder
Trapezoid V = volume; S = area
of cylindrical surface.
A = area. r
h V = r2 h = d2 h
(a + b)h 4
A=
2 S = 6.28rh = 3.14dh
h d Total area A of
b cylindrical surface
and end surfaces:
A = 6.28r(r + h)
= 3.14d(1/2 d + h)

Regular
a
Polygon Cone
s r
R V = volume; A = area
A = area
of conical surface.
r

n = number of sides
s = length of side h d V = 1/3 r2 h
a = 360° ÷ n A = r r2 + h 2
nsr ns R2 - s2
A= 2 = 2 4

Sphere
Circle
V = volume; A = area
A = area; of surface.
d C = circumference. d
r 3 3
r V= 4 r = d
A = r2 = d2 3 6
4 A = 4 r 2 = . d2
C=2 r= D

l Circular Sector
A = area
l = length of arc;
a = angle, in degrees.
r

a r = radius
l = r a 3.14
180
A = 1/2 rl
a = 57.3 l
r

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Reference Data
Formulas,
Conversions and
Engineering
Constants
Conversion Factors
To Convert To... Multiply... By...

Atmospheres (atm) Bar 0.9869

Atmospheres (atm) Inches Mercury (in Hg) 0.03342
Atmospheres (atm) Pounds/square inch (psi) 0.06805
Atmospheres (atm) Torr 0.001316
Bar Atmospheres (atm) 1.0133
Bar Pounds/square inch (psi) 0.06895
British Thermal Units (BTU) Joules (J) 0.000948
British Thermal Units (BTU) Kilowatt-hours (kWH) 3412
British Thermal Units (BTU) Watt-hours (WH) 3.412
British Thermal Units/hour (BTU/h) Kilocalories/hour (kcal/h) 3.969
British Thermal Units/hour (BTU/h) Watts (W) 3.412
British Thermal Units—inches (BTU—in) Watts/meter—°C (W/m—°C) 6.933
hour-square foot—°F (h-ft2—°F)
British Thermal Units/pound (BTU/lb) Kilojoules/kilogram (kJ/kg) 0.4299
British Thermal Units/pound—°F (BTU/lb—°F) Kilojoules/kilogram—°C (kJ/kg—°C) 0.2388
Calories (cal) Joules (J) 0.2388
Centimeters (cm) Feet (ft) 30.48
Centimeters (cm) Inches (in) 2.54
Centimeters/second (cm/s) Feet/minute (FPM) 0.508
Cubic centimeters (cm3 or cc) Cubic feet (ft3) 28,320
Cubic centimeters (cm3 or cc) Cubic inches (in3) 16.39
Cubic centimeters (cm3 or cc) Milliliters (ml) 1.0
Cubic feet (ft3) Cubic meters (m3) 35.32
Cubic feet (ft3) Gallons, U.S. (gal) 0.1337
Cubic feet (ft3) Liters (l) 0.03532
Cubic feet/minute (CFM) Cubic meters/hour (m3/h) 0.5885
Cubic feet/minute (CFM) Cubic meters/second (m3/s) 2119
Cubic feet/minute (CFM) Liters/second (l/s) 2.119
Cubic inches (in3) Cubic centimeters (cm3 or cc) 0.061
Cubic meters (m3) Gallons, U.S. (gal) 0.003785
Cubic meters (m3) Liters (l) 0.001
Cubic meters (m3) Cubic feet (ft3) 0.02832
Cubic meters/hour (m3/h) Cubic feet/minute (CFM) 1.699
Cubic meters/hour (m3/h) Gallons/minute (GPM) 0.2271
Cubic meters/second (m3/s) Cubic feet/minute (CFM) 0.000472
Feet (ft) Centimeters (cm) 0.03281
Feet (ft) Meters (m) 3.281
Feet/minute (FPM) Centimeters/second (cm/s) 1.969
Feet/minute (FPM) Meters/second (m/s) 196.9
Gallons, Imperial Gallons, U.S. (gal) 0.8327

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W A T L O W

Reference Data
Formulas,
Conversions and
Engineering
Constants
Conversion Factors Continued
To Convert To... Multiply... By...

Gallons, U.S. (gal) Cubic feet (ft3) 7.481

Gallons, U.S. (gal) Cubic meters (m3) 264.2
Gallons, U.S. (gal) Gallons, Imperial 1.201
Gallons, U.S. (gal) Liters (l) 0.2642

Reference Data
Gallons/minute (gpm) Cubic meters/hour (m3/h) 4.403
Gallons/minute (gpm) Liters/second (l/s) 15.85
Grams (g) Ounces (oz) 28.35
Grams (g) Pounds (lb) 453.6
Grams/cubic centimeter (g/cm3) Kilograms/cubic meter (kg/m3) 0.001
Grams/cubic centimeter (g/cm3) Pounds/cubic foot (lb/ft3) 0.01602
Grams/cubic centimeter (g/cm3) Pounds/cubic inch (lb/in3) 27.68
Inches (in) Centimeters (cm) 0.3937
Inches (in) Millimeters (mm) 0.03937
Inches Mercury (in Hg) Atmospheres (atm) 29.92
Inches Mercury (in Hg) Torr 25.4
Joules (J) British Thermal Units (BTU) 1055
Joules (J) Calories (cal) 4.187
Joules (J) Watt-hours (WH) 3600
Joules/second (J/s) British Thermal Units/hour (BTU/h) 0.2931
Joules/second (J/s) Watts (W) 1
Kilocalories/hour (kcal/h) BTU/hour (BTU/h) 0.252
Kilograms (kg) Pounds (lb) 0.4536
Kilograms/cubic meter (kg/m3) Grams/cubic centimeter (g/cm3) 1000
Kilograms/cubic meter (kg/m3) Pounds/cubic foot (lb/ft3) 16.02
Kilograms/square centimeter (kg/cm2) Pounds/square inch (psi) 0.07031
Kilojoules (kJ) Watt-hours (WH) 3.6
Kilojoules/kilogram (kJ/kg) British Thermal Units/pound (BTU/lb) 2.326
Kilojoules/kilogram—°C (kJ/kg—°C) British Thermal Units/pound—°F (BTU/lb—°F) 4.187
Kilometers/hour (km/h) Miles/hour (MPH) 1.609
Kilopascals (kPa) Pounds/square inch (psi) 6.895
Kilowatts (kW) British Thermal Units/hour (BTU/h) 0.0002931
Kilowatts (kW) Watts (W) 0.001
Kilowatt-hours (kWH) British Thermal Units (BTU) 0.0002931
Kilowatt-hours (kWH) Watt-hours (WH) 0.001
Liters (l) Cubic Feet (ft3) 28.32
Liters (l) Cubic Meters (m3) 1000
Liters (l) Gallons, U.S. (gal) 3.785
Liters/second (l/s) Cubic feet/minute (CFM) 0.4719
Liters/second (l/s) Gallons/minute (GPM) 0.06309

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Reference Data
Formulas,
Conversions and
Engineering
Constants
Conversion Factors Continued

To Convert To... Multiply... By...

Meters (m) Feet (ft) 0.3048

Meters/second (m/s) Feet/minute (FPM) 0.00508
Miles/hour (MPH) Kilometers/hour (km/h) 0.6215
Millimeters (mm) Inches (in) 25.4
Newtons/square meter (N/m2) Pounds/square inch (psi) 6,895
Ounces (oz) Grams (g) 0.035274
Pounds (lb) Grams (g) 0.002205
Pounds (lb) Kilograms (kg) 2.205
Pounds/cubic foot (lb/ft3) Grams/cubic centimeter (g/cm3) 62.43
Pounds/cubic foot (lb/ft3) Kilograms/cubic meter (kg/m3) 0.06243
Pounds/cubic inch (lb/in3) Grams/cubic centimeter (g/cm3) 0.03613
Pounds/square inch (psi) Bar 14.504
Pounds/square inch (psi) Kilograms/square centimeter (kg/cm2) 14.22
Pounds/square inch (psi) Kilopascals (kPa) 0.145
Pounds/square inch (psi) Newtons/square meter (N/m2) 0.000145
Square centimeters (cm2) Square feet (ft2) 929
Square centimeters (cm2) Square inches (in2) 6.452
Square feet (ft2) Square centimeters (cm2) 0.001076
Square feet (ft2) Square meters (m2) 10.76
Square inches (in2) Square centimeters (cm2) 0.155
Square meters (m2) Square feet (ft2) 0.0929
Torr Inches Mercury (in. Hg) 0.03937
Torr Pounds/square inch (psi) 51.71
Watts (W) British Thermal Units/hour (BTU/h) 0.2931
Watts (W) Joules/second (J/s) 1
Watt-hours (WH) British Thermal Units (BTU) 0.2931
Watt-hours (WH) Joules (J) 0.0002778
Watt-hours (WH) Kilojoules (kJ) 0.2778
Watts/meter—°C (W/m—°C) British Thermal Units—inches (BTU—in) 0.1442
hour-square foot—°F (h-ft2—°F)
Watts/square centimeter (W/cm2) Watts/square inch (W/in2) 0.155
Watts/square inch (W/in2) Watts/square centimeter (W/cm2) 6.452

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