The Difference Between Explosion-Proof Levels IIB and IIC

Explosion-proof equipment within Class II is categorized into: Class IIA, Class IIB, and Class IIC. The ratings follow a hierarchy: IIC > IIB > IIA.

Condition Category	Gas Classification	Representative gases	Minimum Ignition Spark Energy
Under The Mine	I	Methane	0.280mJ
Factories Outside The Mine	IIA	Propane	0.180mJ
	IIB	Ethylene	0.060mJ
	IIC	Hydrogen	0.019mJ

Gas detectors rated for IIC explosion-proof conditions are suitable for all flammable gases; however, IIB detectors fail to detect H2 (hydrogen), C2H2 (acetylene), and CS2 (carbon disulfide), which are characteristic of the IIC class.