Liquefied Petroleum Gase (LPG) is a general abbreviated name of a certain number of mixtures of hydrocarbons such as butane, propane, iso-propane, butane-propane mixture in the liquid state. In normal conditions and under certain pressure which is greater than atmospheric pressure, LPG isstorable, transportable as a liquid, but at atmospheric pressure it is vaporized and used as a gas. LPG is a sub-product of refinery and natural gas separation plant. It is a burning gas which is convenient for transportation due to liquefaction at not too high pressure and at normal temperature. LPG is used as fuel and widely used in industry, commerce, tourism, power generation, transportation, civil using (heating, cooking, heating, lighting,...). The composition of a sample of LPG is obtained by using Test Method ASTM D 2163 or other acceptable method. From, the analysis (expressed in liquid volume percent), the certain physical properties of LPG (vapor pressure, relative density, molecular weight and pro/bu fraction) may be determined.