The Difference Between Explosion-Proof Level AT BT CT

Firstly, all three devices are designed for dust explosion protection and fall under the category of secondary explosion-proof equipment. The explosion-proof ratings are as follows: AT < BT < CT.

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

CT devices feature a superior dust-proof rating and may be utilized in areas designated for AT and BT. However, AT and BT devices are not suitable for areas that require CT standards.

In other words, CT devices can substitute for AT and BT, but AT and BT devices cannot substitute for CT.