LPG is mainly a mixture of propane and butane molecules with a few additives. A strong odorant is added to the otherwise odourless and colourless liquid to allow the slightest leak to be distinguished by olfactory means.
At normal temperature, LPG is in a gaseous state. As pressure increases or temperature decreases, it again reverts to a liquid state. Transporting and storing LPG in steel storage tanks makes this energy source mobile and easy to use.