Liquid Petroleum Gas or LPG is a general naming that refers to liquefied gaseous fuels mainly consisted of saturated hydrocarbons (CvH2v+2) with three or four atoms of carbon (v=3 και v=4).


Such hydrocarbons are products of petroleum refining and under usual temperatures and pressures of environment exist in a gas phase. With a small though pressure increase or light cooling they got liquefied and occupy a very small volume (just 1/250 of the volume of the gas phase). Therefore, the LPG, in its various forms, is storied and delivered mainly in a liquid and not gas phase.

The LPG storage is made in suitable containers (tanks, bottles) either under a mean pressure in environmental temperature or a lower pressure but in a lower though temperature. The liquefaction and storage of LPG is indeed possible even under an atmospheric pressure but in a sufficiently lower temperature.

In a gas phase, LPG bears characteristics that look like those of natural gas. In a liquid phase it looks like benzene as to transfer mode, storage and measuring with a basic though difference that in order to be preserved in a liquid condition it must be under pressure.  In a usual however utility the container that contains LPG, viz. the phial or tank contains gas too.

The special gravity of LPG is approximately the half of water, and LPG’s vapours (gas phase) are heavier that air’s and therefore, in a free condition, they run into ground and drainages, accumulated to lower points.

LPG, besides the other fuels, get burned in a gas phase, in temperatures higher than the flash point, viz. in that temperature that the fuel has to reach to evaporate plenty quantity and have an ignition in the presence of a flame. In an environmental temperature however that is higher than the flash point, enough quantity of LPG is gasificated for the initial feeding of the flame, and with a temperature from a combustion, additional gas or vapour is produced from the liquid fuel.