1.Why need explosion-proof?
Many production sites produce flammable substances. About two-thirds of coal mines contain explosive substances. In the chemical industry, more than 80% of production workshop areas contain explosive substances. The oxygen required for explosions is everywhere.
Electrical instruments used in large quantities in the production process, various friction sparks, mechanical wear sparks, static sparks, high temperatures, etc. are inevitable and are equivalent to ignition sources.
Therefore, in many industrial sites, when the mixed concentration of explosive substances and oxygen reaches the explosion limit, if there is an ignition source, an explosion will occur.
2.Explosion proof certificate signs like EXDIICT6
① "Ex": explosion-proof product mark, domestic explosion-proof marks all start with Ex;
② "d": explosion-proof form of the product;
③ "ⅡC": refers to the dangerous places where the product can be used;
④"T6": temperature group;
⑤"Gb": The equipment protection level of the product;
3.Ex ia IIC T1..T6
IIC is an explosion category determined according to different materials according to EN60079-0.
Group I: Coal mines prone to producing gas, which is methane gas.
Group II: Explosive gas atmosphere
IIA: Gas environment represented by propane.
IIB: Gas environment represented by ethylene.
IIC: Gas environment represented by hydrogen.
Group III: Explosive dust atmosphere
IIIA: Dust environment represented by flammable flying debris.
IIIB: Dust environment represented by non-conductive dust.
IIIC: Dust environment represented by conductive dust.
4.Equipment category
Category I: electrical equipment for underground coal mines;
Category II: Electrical equipment for explosive gas environments other than coal mines.
Class II explosion-proof "d" and intrinsically safe "i" electrical equipment are further divided into classes IIA, IIB, and IIC.
5.Temperature group
According to the maximum surface temperature of the equipment, it is divided into six groups from T1 to T6, as shown in the figure below.
6.Area definition
Zone 0, 1 and 2, gas, vapor and mist environments
Zone 0: Explosive environment where flammable substances are mixed with air in the form of gas, vapor or mist continuously or for a long time or frequently.
Zone 1: Flammable substances may occur or occasionally form during normal operation in the form of gas, vapor or mist mixed with air.
explosive environment.
Zone 2: Where flammable substances are unlikely to occur or form during normal operation in the form of gases, vapors or mist mixed with air.
Explosive atmospheres, or those which, if present, only exist for a short period of time.
Zones 20, 21, 22: Dust environment:
Zone 20: Explosive environments with continuous or long-term or frequent presence of combustible dust in the air;
Zone 21: Explosive atmosphere where combustible dust may or occasionally form in the air during normal operation;
Zone 22: During normal operation, an explosive environment is unlikely to occur or form combustible dust in the air, or even if it occurs
It is also an explosive environment that only exists for a short period of time.
7.Specific categories:
The EPL of Class I equipment in explosive environments with methane in coal mines is divided into two levels: Ma and Mb.
The EPL of Class II equipment in explosive gas environments is divided into three levels: Ga, Gb, and Gc.
The EPL of Class III equipment in explosive dust environments is divided into three levels: Da, Db and Dc.