What Does Explosion-Proof Level ABC Mean

The “abc” represents gas classifications, categorized into three levels—IIA, IIB, and IIC—according to the maximum experimental safe gap (MESG) or the minimum igniting current (MIC).

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

Of these, the IIC classification is deemed the most hazardous, with IIB and IIA following in decreasing order of risk. Gases falling under the IIC classification include hydrogen, acetylene, carbon disulfide, ethyl nitrate, and water gas. Those in the IIB category encompass ethylene, coke oven gas, propyne, and hydrogen sulfide. The IIA classification includes gases such as methane, ethane, benzene, and diesel.