LPG

Liquefied 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.
The butane and propane gases obtained during the distillation of crude oil are the two main petroleum gases. After liquefying these gases, they are mixed at certain rates or offered for sale in pure form and become commercially important.
Liquefied Petroleum Gas is also produced when Natural Gas (Methane) is extracted from the gas fields and ‘dried’ before being piped to homes and industry. LPG has one unique and very special property, If mildly compressed it easily changes to a liquid state. This allows a large amount of gas (stored energy) to be contained in a relatively small space.

The reverse process is just as fortunate – If decompressed (allowed to escape the pressure vessel) the liquid gas will quickly revert to its gaseous state (vapourise).
In other words, store LPG in a pressurized tank and it will remain liquid, occupying only a small space. Release some of the liquid and it will immediately revert to its gaseous state, expanding as it does so.

The most common uses of LPG (liquefied petroleum gas), in industry, is to fuel boilers to generate steam and hot water. LPG can be used with either fire-tube or water-tube boilers.