According to national standards for electrical explosion protection, both BT4 and BT6 fall under Class IIB.
| Класифікація електричного обладнання за температурним режимом | Максимально допустима температура поверхні електричного обладнання (°C) | Температура займання газу/парів (°C) | Клас температури, на який розраховане обладнання |
|---|---|---|---|
| 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.
