Propane Pressure Guidelines

October 29, 2015 by  
Filed under Pressure Guidlines

Data Provided by the Ontario Propane Association (OPA) – More Facts & Guidelines

Facts: Propane (C3H8)is a colorless, odorless, easily liquefied, gaseous hydrocarbon (compound of carbon and hydrogen), and the third member of the paraffin series following methane and ethane. It is separated from light crude oil, natural gas, and is a by-product of petroleum refining. Propane is commercially available as liquefied propane or as a major constituent of liquefied petroleum gas (LPG).

Although a gas at atmospheric pressure, propane has a boiling point of -42.1 C (-43.8 F) and thus is liquefied under elevated pressures. It therefore is transported and handled as a liquid in cylinders and tanks. In this form, alone or mixed with liquid butane, it has great importance as a fuel for domestic and industrial/commercial uses and for internal-combustion engines.

The following properties and combustion data have been taken from various sources and the values shown are for an average commercial grade of propane. It should be kept in mind that the commercial grades can vary and, therefore, the values in the tables will also vary.

Extracted from CAN/CGA-B149.2-M95 Propane Installation Code.

Chemical Formula C3H8
Molecular Weight 44.06
Freezing Point (F) -310
Freezing Point (C) -190
Boiling Point (F) -44
Boiling Point (C) -42
State at atmospheric pressure (60 f, 15 c) Vapour
Relative Density (gas) 1.52
Relative Density (water) 0.51
Mass per gallon of liquid at 60 F 5.1 lbs
Mass per liter of liquid at 15.5 C 0.51
BTU/cu.ft. Vaporized 2520
kJ/cubic meter Vaporized 93,800
BTU/lb. Vaporized 21,622
kJ/kg. Vaporized 49,700
Cubic ft. of vapor from 1 lb. of liquid at 60 F. 8.5
Cubic meters of vapor from 1 kg of liquid at 15 C 0.53
Cubic ft. of vapor from 1 gal. of liquid at 60 F. 44
Cubic meters of vapor from 1 liter of liquid at 15 C 0.265
Latent heat of vaporization at boiling point, BTU/gal. 944
Specific enthalpy, kJ/L 219
Cubic feet (meters) of air required to burn 1 cubic ft. (meter) of gas 23.5
Cubic feet (meters) of oxygen required to burn 1 cubic ft. (meter) of gas 5
Cubic feet of air required to burn 1 lb. of gas. 200
Cubic meters of air required to burn 1 kg. of gas. 12.3
Ignition temperature F. (C) 920-1020 (493-549)
Maximum flame temperature F (C) 3600 (1982)
Percentage of gas in air for maximum flame temperature 4.4
Lower and upper limits of flammability (percentage of gas in air) 2.4 to 9.5
Octane number (iso-octane 100) 97 to 125

Heating propane cylinders to increase pressure can be done safely and economically by utilizing a heated propane jacket or wrap often referred to as a GCW – Gas Cylinder Warmer.  See Powerblanket for more details: LINK: