Butane is liquefied gas that comes from petrol, the same as propane. It is a hydrocarbon, composed of four atoms of carbon and ten of hydrogen (C4HI0), it is gaseous and inflammable, and it liquefies at an atmospheric pressure of -0.5�C.

In addition it is colourless and odourless: when sold sulphur salts called mercaptans are added to give it an unpleasant odour so that a leak can be detected. If it does catch fire, carbon anhidride (CO2), chemical dust or water mist must be used to extinguish it by cooling it and dispersing vapours.

History
In 1957 the company Butano, S.A., now Repsol Butano, S.A., was created. The company had a monopoly on the purchase of butane and propane gas in Spain. The popular butane canister with its wide distribution ensured that Spanish homes in many small and medium-sized towns had access to this form of energy for the first time.

A large number of homes still have household apparatus that run on butane gas.

Commercial use
Due to transport and distribution limitations, butane gas is not usually supplied in large quantities. In Spain it is transported in the typical orange-coloured canister, a cylindrical container made of steel containing 12.5 kilograms of butane gas. There are also smaller canisters, such as those of 6 kilograms, and lighter ones, made from other materials such as aluminium.

Each butane canister weighs 35 kilos and is mainly used for domestic appliances such as hobs and ovens, hot water heaters and portable heaters.