Shenhai Explosion-Proof
According to national standards for electrical explosion protection, both BT4 and BT6 fall under Class IIB.
| Temperature group of electrical equipment | Maximum allowable surface temperature of electrical equipment (℃) | Gas/vapor ignition temperature (℃) | Applicable device temperature levels |
|---|---|---|---|
| T1 | 450 | ＞450 | T1~T6 |
| T2 | 300 | ＞300 | T2~T6 |
| T3 | 200 | ＞200 | T3~T6 |
| T4 | 135 | ＞135 | T4~T6 |
| T5 | 100 | ＞100 | T5~T6 |
| T6 | 85 | ＞85 | T6 |
However, the ‘T’ classification pertains to the temperature rating of explosion-proof electrical devices. Devices classified as T6 must maintain a surface temperature no higher than 85°C, T5 must not exceed 100°C, and T4 must not surpass 135°C.
The lower a device’s maximum surface temperature, the less likely it is to ignite atmospheric gases, thereby enhancing safety. Consequently, the explosion-proof rating of BT6 exceeds that of BT4.