The explosion-proof classification dⅱ bt4 for electrical equipment surpasses dⅱ bt2, differing only in the classification numbers 4 and 2.
| Temperature Classification for Electrical Equipment | Maximum Permissible Surface Temperature of Electrical Equipment (°C) | Gas/Vapor Ignition Temperature (°C) | Applicable Equipment Temperature Class |
|---|---|---|---|
| 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 |
Classification T4 specifies that the gas ignition temperature is under 135°C, whereas T2 allows for temperatures up to 300°C.
Ignition temperatures are divided into six categories, ranging from T1 to T6, with each higher category being suitable for the conditions of all preceding categories.
