propaneair

Propane-air is a gaseous fuel mixture composed of propane (C3H8) dispersed in air. The proportion of propane in the mix largely determines its flammability. In air at room temperature, propane is ignitable over a volume fraction roughly from 2.1% to 9.5%; mixtures below or above these limits are too lean or too rich to ignite. The autoignition temperature of propane in air is about 470–520°C, and the flame temperature depends on the mixture and pressure.

Propane is denser than air, so leaks can accumulate in low-lying areas if not properly ventilated. Commercial propane is often odorized with a sulfur-containing compound (such as mercaptan) to aid leak detection. Inhalation of high concentrations can cause asphyxiation; contact with flames or hot surfaces poses fire and explosion risks.

Common applications include fuel for metalworking torches, brazing and soldering, and various heating and heating-blasting applications that require a portable, clean-burning flame. In industrial settings, propane-air burners are used where gaseous fuels are preferred or where LPG systems are not available. It is also used in some research and industrial processes that require controlled gas-air combustion.

Storage and handling require careful attention to safety and codes: propane is stored as a liquid under pressure in cylinders or tanks, and must be kept away from heat sources, sparks, and open flames. Regulators and proper fittings are used to control delivery. Adequate ventilation is essential to prevent accumulation, and equipment should be designed to manage the risk of leaks and static discharge.

Environmental considerations include the combustion products, primarily carbon dioxide and water, with propane contributing minimal sulfur emissions compared with many other fuels.