LPG stands for "Liquefied Petroleum Gas" and is a fuel gas that contains a flammable mixture of hydrocarbon gases, specifically propane, propylene, butylene, isobutane, and n-butane. It is primarily obtained from natural gas and oil production but is also produced increasingly from renewable sources. LPG is used as a fuel gas in heating appliances, cooking equipment, and vehicles. It is increasingly used as an aerosol propellant and a refrigerant, replacing chlorofluorocarbons in an effort to reduce damage to the ozone layer. When specifically used as a vehicle fuel, it is often referred to as autogas or even just as gas.
Propane is the most common type of LPG, followed by butane, and mixes of both. It is stored under pressure inside a tank as a colorless, odorless liquid. As pressure is released, the liquid propane vaporizes and turns into gas that is used in combustion. An odorant, ethyl mercaptan, is added for leak detection. Propane has a high octane rating, making it an excellent choice for spark-ignited internal combustion engines. LPG-fueled vehicles can also emit lower amounts of some air pollutants and greenhouse gases, depending on vehicle type, calibration, and drive cycle.
