Explosion-proof box model:

The current national standard for explosion-proof electrical equipment is GB3836. GB3836 divides explosion-proof electrical equipment into ten types: flameproof, increased safety, intrinsically safe, positive pressure, oil-filled, sand-filled, non-sparking, potting, airtight and special.

1. Flameproof electrical equipment: Electrical equipment with a flameproof enclosure is called flameproof electrical equipment. The flameproof shell can not only withstand the explosion pressure generated by the detonation of the internal mixed gas, but also prevent the internal explosion flame and high temperature gas from breaking out of the flameproof gap to ignite the explosive mixture around the shell. This type of equipment is marked with a "d".

2. Increased safety electrical equipment: electrical equipment at high temperature points that will not produce arcs, sparks or may ignite explosive mixtures under normal operation, take measures on its structure to improve safety to avoid occurrences under normal or specified overload conditions. Arcs, sparks or electrical equipment that may ignite explosive mixtures are called increased safety electrical equipment. This type of equipment is marked with an "e".

3. Intrinsically safe electrical equipment: Electrical equipment whose all circuits are intrinsically safe circuits is called intrinsically safe electrical equipment. The so-called intrinsically safe circuit refers to a circuit that can not ignite an explosive mixture under specified conditions, in normal operation or under specified fault conditions. The symbol of this type of equipment is "i" (divided into ia, ib).

4. Positive pressure electrical equipment: Electrical equipment with positive pressure housing is called positive pressure electrical equipment. The so-called positive pressure shell is a shell that injects a protective gas into the shell to keep the pressure of the inner protective gas higher than the pressure of the surrounding explosive environment to prevent the external explosive mixture from entering the shell. This type of equipment is marked with a "P".

5. Encapsulation type: The electrical equipment that encapsulates the conductive parts in the encapsulant and is isolated from the dangerous gas is called the encapsulation type electrical equipment. It is marked with "m".

6. Air-tight type: Electrical equipment that uses a completely sealed metal casing and is isolated from dangerous gases is called air-tight electrical equipment. The device flag is "h".