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Propane Cylinder Capacities and Estimating Propane Consumption

Propane Cylinder Capacities

Nominal Size Gallon Capacity BTU Capacity
10# 2.36 215,807
20# 4.72 431,613
30# 7.08 647,420
40# 9.43 863,226

The above capacities allow for the 20% vapor space that must be left in a full cylinder.

Estimating propane consumption

To estimate roughly how long your propane gas supply will last, divide the storage capacity of your supply tank or cylinder(s) in BTU by the gas consumption of your appliance(s). An appliance's rated consumption should be in its manual or on its nameplate.

Properties of LP-Gas

Pounds per gallon 4.24
Specific gravity of gas 1.50
Specific gravity of liquid 0.504
Cu. ft. gas per gallon liquid 36.38
Cu. ft. gas per pound 8.66
BTU per gallon 91,502
BTU per pound 21,548
Boiling point in deg F at 14.7 psia -44
Vapor pressure at 0 deg F 31
Vapor pressure at 70 deg F 127
Vapor pressure at 100 deg F 196
Vapor pressure at 115 deg F 230

Unit Conversions

1 gallon = 3.785 liters

11 in. Water Column = 6-1/4 ozs. per sq. in. pressure

27.7 in. Water Column = 1 pound per sq. in. pressure

Here is a link to Manchester Tank's Helpful Hints page where I found these useful tables. Manchester Tank is a leading manufacturer of Propane Cylinders and Tanks used in the RV industry.

Tags: Propane