1. It is applicable to the places in Zone 1 and Zone 2 of explosive gas environment; 2. It is applicable to the places in Zone 21 and 22 of combustible dust environment; 3. Suitable for IIA, IIB and IIC explosive gas environment; 4. Applicable to T1~T6 temperature groups; 5. It is applicable to hazardous environments such as oil exploitation, oil refining, chemical industry, gas station, offshore oil platforms, oil tankers, and metal processing.