Propane The lowest flammability range of any of the commonly available fuel gases.

Propane (C₃H₈) is a colourless and highly flammable liquefied gas – although it has the lowest flammability range of any of the commonly available fuel gases. As a constituent of natural gas, it is obtained by refining and processing natural gas. Propane is heavier than air, with both a primary and secondary flash temperature. It is one of the main components in liquid petroleum gas (LPG) along with butane. As the ratios of these LPG gases vary from one supplier to another, the flame properties can also differ.

Also known as autogas, propane is widely used as a car fuel, although it is also popular for industrial and domestic heating. Clean burning characteristics make propane ideal for a wide range of industrial and agricultural applications. These include oxy-propane cutting and brazing, soldering, preheating, heat treatment, shrink-wrapping, drying crops, heating greenhouses and livestock sheds as well as for flame-weeding and pest control. It is also employed in its pure form as the fuel gas in flame photometers.

As a specialty gas, it is used in mixtures to calibrate process control analyzers in the petrochemical industry. It is also employed as a refrigerant and in refrigerant blends and as an aerosol propellant. Other applications include controlled atmospheres in metallurgy, the production of various chemicals, efficiency testing of gas burners and engines and calibration gas mixtures.