The categorisation of Gas Groups for Electrical Apparatus which includes all potentially explosive gas, vapour, or chemical would normally be found in the appropriate National or International Code of Practice related to the users location.

A selection of typical gas groups is shown below. Users may refer to PD IEC 60079-20, "Electrical apparatus for explosive gas atmospheres : Data for flammable gases and vapours, relating to the use of electrical apparatus", for a comprehensive collection of reference characteristics.

Gas Group Typical Gas Name
IA Methane (Firedamp) - Mining
IIA Industrial Methane, Propane, Petroleum & Hydrocarbons
IIB Ethylene & Town Gas, Coke Oven Gas
IIC Hydrogen, Acetylene, Carbon Di-Sulphide