الوصف

Liquified petroleum gas or liquid petroleum gas (LPG or LP gas), also referred to as simply propane or butane, are flammable mixtures of hydrocarbon gases used as fuel in heating appliances, cooking equipment, and vehicles.
It is increasingly used as an aerosol propellant and a refrigerant[citation needed], 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.
Propylene, butylenes and various other hydrocarbons are usually also present in small concentrations. HD*5 limits the amount of propylene that can be placed in LPG to 5%, and is utilized as an autogas specification. A powerful odorant, ethanethiol, is added so that leaks can be detected easily. The internationally recognized European Standard is EN **9. In the United States, tetrahydrothiophene (thiophane) or amyl mercaptan are also approved odorants,[5] although neither is currently being utilized.
LPG is prepared by refining petroleum or "wet" natural gas, and is almost entirely derived from fossil fuel sources, being manufactured during the refining of petroleum (crude oil), or extracted from petroleum or natural gas streams as they emerge from the ground. It was first produced in ***0 by Dr. Walter Snelling, and the first commercial products appeared in ***2. It currently provides about 3% of all energy consumed, and burns relatively cleanly with no soot and very few sulfur emissions. As it is a gas, it does not pose ground or water pollution hazards, but it can cause air pollution. LPG has a typical specific calorific value of *6.1 MJ/kg compared with *2.5 MJ/kg for fuel oil and *3.5 MJ/kg for premium grade petrol (gasoline).[6] However, its energy density per volume unit of *6 MJ/L is lower than either that of petrol or fuel oil, as its relative density is lower (about 0.*0.*8 kg/L, compared to 0.**0.*7 kg/L for gasoline).