Firstly, all three devices are designed for dust explosion protection and fall under the category of secondary explosion-proof equipment. The explosion-proof ratings are as follows: AT < BT < CT.
| Usage Area | Gas Classification | Representative Gas | Minimum Ignition Spark Energy |
|---|---|---|---|
| Under The Mine | I | Methane | 0.280mJ |
| Factories Outside The Mine | IIA | Propane | 0.180mJ |
| IIB | Ethylene | 0.060mJ | |
| IIC | Hydrogen | 0.019mJ |
CT devices feature a superior dust-proof rating and may be utilized in areas designated for AT and BT. However, AT and BT devices are not suitable for areas that require CT standards.
In other words, CT devices can substitute for AT and BT, but AT and BT devices cannot substitute for CT.
