Explosion proof level, which level is higher between CT and BT？
2016/12/2 view:
Ex d Ⅱ C T5
①②③④ ⑤
①It is the explosion-proof mark of China and the International Electrotechnical Commission.
②D refers to explosion-proof type.
③Simply put, II refers to electrical equipment other than those used in coal mines and underground mines.
Ⅰ——Coal mine and underground electrical equipment
Ⅱ——Factory electrical equipment
④和⑤They'are the key point we're going to talk about here today.
| Working condition | Level | Gas | Minimum ignition spark energy | MESG(mm) | MICR |
| underground coal mine | Ⅰ | methane | 0.280mJ |
|
|
| Factories outside the mine | ⅡA | propane | 0.180mJ | MESG≥0.9 | MICR＞0.8 |
| ⅡB | ethylene | 0.060mJ | 0.9＞MESG＞0.5 | 0.8≥MICR≥0.45 | |
| ⅡC | hydrogen | 0.019mJ | 0.5≥MESG | 0.45＞MICR |
In the table above, Group A is the least explosive, Group C is the most explosive, and Group B is in the middle. The vast majority of common gases belong to Group A or Group B, with only a few gases such as hydrogen belonging to Group C. Equipment adapted to Group C gases can be used for explosion prevention in Groups A, B, and C. Equipment adapted to Group B can be used for explosion prevention in Groups A and B, while equipment adapted to Group A gases can only be used for Group A.
So, the explosion-proof rating of BT is lower than that of CT, for example, the explosion-proof rating of BT4 is equal to CT4
| Temperature group | T（℃） | Common explosive gases | Equipment allows surface temperature（℃） |
| T1 | T≥450 | 46 types of hydrogen, acrylonitrile, etc | 450 |
| T2 | 450＞T≥300 | 47 types of acetylene, ethylene, etc | 300 |
| T3 | 300＞T≥200 | 36 types of gasoline, butenal, etc | 200 |
| T4 | 200＞T≥135 | Six types including acetaldehyde, tetrafluoroethylene, etc | 135 |
| T5 | 135＞T≥100 |
carbon disulfide |
100 |
| T6 | 100＞T≥85 | Ethyl nitrate and ethyl nitrite | 85 |
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