545
Appendix M: Constants, Conversion
Factors, and Units
Constants
Universal gas constant
ℜ
= 8.314 kJ/kmol · K
= 1545.33 ft lbf/lbmol°R
Atmospheric pressure p
atm
= 0.101 325 MPa
= 101.325 kPa
= 1.013 25 bar
Speed of light in a vacuum c
0
= 2.998 × 10
8
m/s
Gravitational acceleration at sea level g = 9.807 m/s
2
= 32.17 ft/sec
2
Conversion Factors
Area (A) 1 m
2
= 10.764 ft
2
1 ft
2
= 0.0929 m
2
Density (ρ)
1 kg/m
3
= 0.062 428 lbm/ft
3
1 lbm/ft
3
= 16.019 kg/m
3
Energy, work 1 kJ = 737.56 ft · lbf
1 ft · lbf = 1.3558 J
1 btu = 778.17 ft · lbf
1 btu = 1.0551 kJ
Force 1 N = 0.224 81 lbf
1 lbf = 4.4482 N
Heat ux (q) 1 W/m
2
= 0.317 00 btu/h · ft
2
1 btu/h · ft
2
= 3.154 69 W/m
2
Heat transfer coefcient (h) 1 W/m
2
· K = 5.6783 btu/h · ft
2
· °F
1 btu/h · ft
2
· °F = 0.1761 W/m
2
· K
Heat transter rate (Q) 1 W = 3.4118 btu/h
1 btu/h = 0.293 07 W
Kinematic viscosity (ν)
1 m
2
/s = 38 750 ft
2
/h
1 ft
2
/h = 2.581 × 10
−5
m
2
/s
Length 1 m = 3.2808 ft
1 ft = 0.304 80 m
Mass 1 kg = 2.2046 lbm
1 lbm = 0.453 59 kg
Pressure, stress (p, τ)
1 kPa = 0.145 04 lbf/in
2
1 lbf/in
2
= 6.894 75 kPa
Power 1 W = 0.073 756 ft · lbf/s
1 btu/h = 0.029 307 W
1 hp = 0.074 570 kW
Specic heat (c
p
, c
υ
)
1 kJ/kg · °C = 0.238 85 btu/lbm · °F
1 btu/lbm · °F = 4.1868 kJ/kg · °C
Temperature (T) T (K) = T (°C) + 273.15
T (°C) = 5/9(T (°F) − 32)
T (°R) = T (°F) + 459.67
546 Appendix M
Conversion Factors
T (°F) = 1.8 T (°C) + 32
Temperature difference (ΔT)
1°C = 1 K
1°C = 1.8°F
1°F = 1°R
1°F = 0.555 56°C
Thermal conductivity (k) 1 W/m · K = 0.5782 btu/h · ft · °F
1 btu/h · ft · °F = 1.7295 W/m · K
Thermal diffusivity (α)
1 m
2
/s = 38 750 ft
2
/h
1 ft
2
/h = 2.5807 × 10
−5
m
2
/s
Velocity 1 m/s = 3.2808 ft/s
1 ft/s = 0.304 80 m/s
Viscosity (μ)
1 N · s/m
2
= 2419.1 lbm/ft · h
= 5.8016 × 10
−6
lbf · h/ft
2
Volume (V) 1 m
3
= 35.315 ft
3
1 ft
3
= 0.028 317 m
3

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