In both gas and temperature categories, BT4 exceeds AT3, therefore providing a higher explosion-proof rating.
| III | C | T 135°C | Db | IP65 |
|---|---|---|---|---|
| III Surface dust | T1 450°C | Ma | IP65 | |
| T2 300°C | Mb | |||
| T3 200°C | ||||
| A Flammable flying flocs | Da | |||
| T4 135°C | ||||
| Db | ||||
| B Non conductive dust | T2 100°C | Dc | ||
| C Conductive dust | T6 85°C |
Class A includes gases such as ethane, methanol, ethanol, and gasoline; Class B comprises gases like residential gas, ethylene, and ethylene oxide.
The T3 temperature classification applies to environments up to 200°C and includes 36 common gases such as gasoline and butyraldehyde. The T4 classification limits temperatures to 135°C, also for 36 gases including acetaldehyde and tetrafluoroethylene.
