Explosive gas environments are categorized into three levels—A, B, and C—based on the maximum experimental safe gap or the minimum ignition current required.
| Gas Classification | Temperature Group | |||||
|---|---|---|---|---|---|---|
| - | T1 | T2 | T3 | T4 | T5 | T6 |
| - | T＞450 | 450≥T＞300 | 300≥T＞200 | 200≥T＞135 | 135≥T＞100 | 100≥T＞85 |
| I | Methane | |||||
| IIA | Ethane, Propane, Acetone, Phenethyl, Ene, Aminobenzene, Toluene, Benzene, Ammonia, Carbon Monoxide, Ethyl Acetate, Acetic Acid | Butane, Ethanol, Propylene, Butanol, Acetic Acid, Butyl Ester, Amyl Acetate Acetic Anhydride | Pentane, Hexane, Heptane, Decane, Octane, Gasoline, Hydrogen Sulfide, Cyclohexane, Gasoline, Kerosene, Diesel, Petroleum | Ether, Acetaldehyde, Trimethylamine | Ethyl Nitrite | |
| IIB | Propylene, Acetylene, Cyclopropane, Coke Oven Gas | Epoxy Z-Alkane, Epoxy Propane, Butadiene, Ethylene | Dimethyl Ether, Isoprene, Hydrogen Sulfide | Diethylether, Dibutyl Ether | ||
| IIC | Water Gas, Hydrogen | Acetylene | Carbon Disulfide | Ethyl Nitrate | ||
Devices are organized into six temperature classifications, ranging from T1 to T6, determined by the maximum allowable surface temperature.
