IIC designations are used in environments containing hazardous gases like hydrogen, acetylene, and carbon disulfide, while IIIC designations apply to areas with conductive dust.
| 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 | ||
The ‘T’ classification indicates the maximum surface temperature of equipment: T1 up to 450°C, T2 up to 300°C, T3 up to 200°C, T4 up to 135°C, T5 up to 100°C, and T6 up to 85°C.
The T6 classification is the highest, signifying the lowest permissible surface temperature.
