ICOM Propane Conversions »Physical Properties of Propane

The Molecular Makeup of Propane | Cusson AutomotiveThe molecular makeup of propane consists of 3 Carbon molecules and 8 Hydrogen molecules.

Propane is a hydrocarbon fuel (C3H8) sometimes referred to as Liquefied Petroleum Gas, LP-gas, or LPG. Propaneis produced from both natural gas processing and crude oil refining, in roughly equal amounts from each source. Nearly 97 percent of propane consumed in the United States is produced in North America. It is nontoxic, colorless, and virtually odorless. As with natural gas, an identifying odor is added so the gas can be readily detected.

Propane is an approved, clean fuel listed in the 1990 Clean Air Act and the Energy Policy Act of 1992 and is one of the cleanest burning of all fossil fuels. Tests conducted by the U.S. Environmental Protection Agency show that propane-fueled vehicles produce 30 percent to 90 percent less carbon monoxide and about 50 percent fewer toxins and other smog-producing emissions than gasoline engines. Propane also is nontoxic, so it’s not harmful to soil or water.

Propane is used by millions of Americans each day. People use propane in and around their homes for furnaces, water heaters, air conditioners, outdoor grills, fireplaces, and appliances.

On farms, propane-fueled equipment and technologies control pests, dry crops, and power irrigation pumps. Industrial uses include propane-driven forklifts and fleet vehicles and millions of commercial establishments, including restaurants and hotels, depend on propane for heating, cooking, and other uses. Up to 56,000 miles of pipeline and more than 6,000 retail dealer locations make propane readily available throughout the United States. And because propane is stored in portable tanks, it can be used in areas beyond gas mains.

Refueling a propane vehicle takes about the same time as refueling a gasoline vehicle. And propane is the only alternative fuel with fueling stations located in every state. Propane is a safe and environmentally friendly fuel that is available now and widely used throughout the United States in homes, on farms, on the road, and in industrial and commercial operations.

Property Natural Gas Propane Butane
Chemical Formula CH4 C3H8 C4H10
Boiling Point of Liquid @ Atmospheric Pressure -258.7ºF -43.7ºF 31.1ºF
Vapor Pressure PSIG @ -20ºF Approx 1800 10 ---
Vapor Pressure PSIG @ 0ºF --- 24 ---
Vapor Pressure PSIG @ 20ºF --- 41 ---
Vapor Pressure PSIG @ 40ºF --- 63 3
Vapor Pressure PSIG @ 70ºF --- 109 17
Vapor Pressure PSIG @ 100ºF --- 172 40
Calorific Value: BTU/CF @ 60ºF 1012 2520 3350
Calorific Value: BTU/Gallon @ 60ºF --- 91500 103000
Latent Heat of Vaporization: BTU/Gallon 712 774 808
Liquid Weight: Lbs./Gallon 2.5 4.23 4.86
Vapor Specific Gravity 0.6 1.52 2
C.F. of Vapor Formed from 1 Gallon of Liquid at 60ºF 59 36.38 31.26
Combustible Limits % of Gas in Air 5-15 2.15–9.6 1.9-8.4
C.F. of Air Required to Burn 1 C.F. of Gas 9.53 23.82 30.97