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