Book - School of Science and Technology

Appendix III 705Imperial units to SI (continued)Unit Imperial Exact ApproximateIntensity of heat flow rate 1 Btu/sq. ft hour 3.155 W/m 2 3 W/m 2Transmittance (U value)1 Btusq: ft hour F5.678 W/m 2 K 6 W/m 2 KConductivity (k value)1 Btu inchsq: ft hour F0.1442 W/m KResistivity (1/k)1sq: ft hour FBtu inch6.934 m K/WCalorific value 1 Btu/lb 2.326 kJ/kg 2.5 kJ/kg1 Btu/cu. ft 37.26 J/litreor 37.26 kJ/m 3Pressure 1 pound force per sq. in 6895 Pa 7000 Pa(lb f/sq. in) or 68.95 mbar 70 mbar1 inch w.g. (at 4 C) 249.1 Pa 250 Paor 2.491 mbar2.5 mbar1 inch mercury (at 0 C) 33.86 mbar 34 mbar1 mm mercury 1.333 mbar1 atmosphere (standard) 101 325 Pa 1 barPressure drop 1 inch w.g./100 ft 8.176 Pa/mLatent heat of steam(atmospheric pressure) 970 Btu/lb 2258 kJ/kg 2300 kJ/kgLatent heat of fusionof ice 144 Btu/lb 330 kJ/kgSteam flow rate 1 lb/hr 0.126 g/s8 lb/hr ± 1 g/sHeat content 1 Btu/lb 2.326 kJ/kg1 Btu/gall 0.2326 kJ/litre1 Btu/cu. ft 0.0372 kJ/litreThermal diffusivity 1 ft 2 /hr 2:581 10 5 m 2 =sMoisture content 1 lb/lb 1 kg/kg100 grains/lb 0.014 kg/kgSI