The hottest and most efficient of all fuel gases, acetylene (C2H2) provides high levels of productivity thanks to good localised heating with a minimum of thermal waste. It also requires the least amount of oxygen to ensure complete combustion. This flammable, colourless gas is lighter than air so does not accumulate at low levels, where it could cause a potential hazard. It is generally supplied dissolved in acetone or DMF (dimethylformamide) in specially designed cylinders to prevent decomposition.
A low flame moisture content makes this fuel gas a good choice for many critical heating processes. Typical applications include flame heating, flame gouging, welding, flame hardening, flame cleaning, flame straightening, thermal spraying, spot-heating, brazing, texturing, profile-cutting, branding wooden pallets, wood-ageing and carbon coating.
Acetylene is the only fuel gas recommended for underground working conditions because it is lighter than air. It is also the only fuel gas, for instance, which can be used to weld steel.
In cutting, oxy-acetylene gives the fastest preheating and piercing times of any fuel gas combination.
In atomic absorption flame spectroscopy, acetylene is combined with high-purity synthetic air or nitrous oxide as a fuel for the flame.
Beyond its obvious value as a fuel gas, acetylene has many other less-well-known applications. It is used to produce certain plastics and chemicals for instance. It also plays a role in organic synthesis (laboratory work) and chemical synthesis. In plant cultivation, it improves the forming of new flowers. It is also used as a carbon source in molecular manufacturing, in calibration gases for the gas, oil and chemical industries and in lung testing gases.
Acetylene is manufactured commercially by reacting calcium carbide and water. It is also a by-product of ethylene production.