Book - School of Science and Technology

312 Fuels, storage and handlingTable 11.10 Properties of natural and liquefied petroleum gasCommercial LPGItem Natural gas Butane PropaneSpecific massas gas at 15 C (kg/m 3 ) 0.78 2.45 1.85as gas at 15 C(re air ˆ 1) 0.60 2.0 1.5as liquid (kg/litre) ± 0.575 0.512Volume of gasper volume of liquid (m 3 /m 3 ) ± 233 274per mass of liquid (m 3 /kg) ± 0.41 0.54Calorific value (gross)re mass (MJ/kg) 53.3 49.2 50as gas (MJ/m 3 ) 41.6 121.5 95as liquid (MJ/litre) ± 28.2 25.5Ignition temperature 650 510 510Operating pressure (kPa) 2 3.7 3.7Toxicity Nil Nil NilTable 11.11 Storage of liquefied petroleum gases (LPG)Cylinder Capacity Size (mm)GasColourPressure(kPa)kgLiquid a(litre) Gas (m 3 )Height orlengthDiameterNormal offtake(litre/s)Butane Blue 172 4.5 7.8 1.8 340 240 0.047 12.2 2.8 495 256 0.0615 26.1 6.1 580 318 0.08Propane Red 690 13 25.4 7.0 580 318 0.1619 37.2 10.2 810 318 0.247 92 25.2 1290 375 0.35White 690 615 1200 330 2000 1000 1.6or 1020 2000 550 3000 1000 2.0Green 1735 3400 930 3800 1200 3.7White 690 715 1400 380 Sphere 1500 1.82040 4000 1100 3800 1200 4.4a Notional capacity 87% fill at 15 C.Note: larger bulk storage tanks of 24 m 3 are available but no standard sizes exist.Storage pressure for propane is 690 kPa and this is reduced to about 75 kPa at a firststage regulator which supplies the primary distribution main running up to the outside ofa building. A second stage regulator fitted there will have an output at 3.7 kPa to suit thestandard low pressure input rating for which most utilisation equipment is designed.PipeworkFrom the second stage regulator, pipework for LPG should be sized using the sameprinciples as have been set out previously for natural gas but using the data in Table 11.12.