In general usage, LPG (Liquefied Petroleum Gas) refers to propane, butane and their mixtures which remain liquid at room temperature under relatively low pressure. It occurs as a by-product in crude oil refining and as an associated gas in the exploitation of crude oil and natural gas. Apart from heating and domestic cooking, it also serves as a fuel for vehicles with an Otto engine. Therefore, the mixed gas is also called "propellant gas".
Liquefied gas, in contrast to crude oil, is not transported via pipelines but in large sea-going vessels, small barges, railway tank wagons and road tank vehicles to dealers or also directly to the liquefied gas tanks or vehicle gas stations of final consumers. The low pressure of propane and butane make this flexible transport of liquefied gas possible.
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