14 BRIGGSandSTRATTON.COM
Physical Properties LP Vapor Natural Gas
Normal Atmospheric State Gas Gas
Boiling Point (in °F):
Initial
End -44
-44 -259
-259
Heating Value:
BTU per gallon (Net LHV*)
BTU per gallon (gross**)
Cubic feet (gas)
83,340
91,547
2,500
63,310
1,000
Density*** 36.39 57.75
Weight† 4.24 2.65
Octane Number:
Research
Motor 110+
97 110+
* LHV (Low Heat Value) is the more realistic rating.
** Gross heat value does not consider heat lost in the form of water
during combustion.
*** Density is given in “Cubic Feet of Gas per Gallon of Liquid”.
† Weight is given in “Pounds per Gallon of Liquid”.
Fuel Comparison Chart
Required Propane Tank Size
The required size of the propane tank at various
temperatures when kept at least half full is shown below
in the chart. Given the gas withdrawal rate and the lowest
average winter temperature, an installer can specify the
required LP storage tank size.
Withdrawal Rate 32° F 20° F 10° F 0° F -10° F -30° F -40° F
50 CFH 115 115 115 250 250 400 600
100 CFH 250 250 250 400 500 1000 1500
150 CFH 300 400 500 500 1000 1500 2500
200 CFH 400 500 750 1000 1200 2000 2500
300 CFH 750 1000 1500 2000 2500 4000 5000