Gases are classified according to the ignitability of gas-air mixture.
Refer to EN 60079-20-1 for classification of common gases and vapours.
| Gas Groups |
Representative Test Gas |
| I | Methane (mining only) |
| IIA (least easy to ignite) | Propane |
| IIB | Ethylene |
| IIC (most easy to ignite) | Hydrogen + Acetylene |
