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The explosion-proof sign is a string of letters and numbers, and it will be more confused if you don't understand. In fact, the explosion-proof sign can be divided into several parts, each part has its own meaning.
Explosion-proof signs, such as Exd IIC T6 Gb, are composed of explosion-proof type + equipment category (gas category) + temperature group + equipment protection level.
The symbol Ex, the mark of electrical equipment for explosion-proof gas atmospheres.
Explosion-proof type:
In the fire protection industry, flameproof type "d" and intrinsically safe type "ib" are common (see the red box of equipment protection level Gb in the table below).
Explosive gas category:
1. Class I: coal mine gas gas;
2. II.I A, IIB and IIC: Other explosive gases other than coal mine gas atmosphere, see the following table.
Class II.B: representative gas is ethylene;
Class II.C: The representative gas is hydrogen.
Explosive gas mixtures shall be classified according to their maximum test safety clearance (MESG) or minimum ignition current ratio (MICR). The classification of explosive gas mixtures shall comply with the provisions of the following table.
Temperature group:
Explosive gas mixtures shall be grouped according to the ignition temperature, and the ignition temperature grouping shall comply with the provisions of the following table.
Device Protection Level (EPL) :(sometimes omitted)
Choice of protection levels for electrical equipment in explosive atmospheres
The protection level of equipment in gas/vapor environment is Ga, Gb, Gc, and the protection level of equipment in dust environment should reach Da, Db, Dc.
"EPL Gb" equipment for explosive gas atmospheres has a "high" protection rating and will not become a source of ignition during normal operation and under expected fault conditions.