Explosion-proof equipment is designed on the principle that the equipment itself will not become a source of ignition in an explosive atmosphere, nor will it produce sparks or overheat the surface.
Class I: electrical equipment underground in coal mines;
Class II: electrical equipment for all other explosive gas atmospheres except coal mines and underground mines.
Class II can be further divided into classes IIA, IIB and IIC. The equipment marked with IIB can be applied to the operating conditions of IIA equipment; IIC can be applied to the operating conditions of IIA and IIB.
Class III: Electrical equipment in explosive dust atmospheres other than coal mines.
Class IIIA: flammable flying flocs; Class IIIB: non-conductive dust; Class IIIC: conductive dust.
Explosion-proof form
1. Intrinsically safe "i" (intrinsically safe electrical equipment and associated equipment) Intrinsically safe circuits:
2. Flameproof type "d" Electrical equipment with flameproof enclosure.
3. Increased safety e
4. Oil-filled o
5. Sand filled type q
6. Encapsulation type m
7. Compound
