Shenhai Explosion-Ubungqina
Exd IIC T4 and Exd IIC T5 share similar explosion-proof ratings, with the sole distinction being the maximum temperature each can reach during operation.
| 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 |
The maximum permissible surface temperatures differ: for Exd IIC T4, it is 135 degrees Celsius, whereas for Exd IIC T5, it is capped at 100 degrees Celsius.
Given that lower operating temperatures enhance safety, the explosion-proof classification CT5 is considered superior to CT4.