Classification of explosion-proof electrical equipment

Explosion-proof electrical equipment refers to electrical equipment that can be used in hazardous places, explosive gases, and combustible dust environments to prevent sparks, arcs, or dangerous high temperatures. Prevent the explosion of surrounding gas mixtures. It is usually used in coal mining, chemical industry, petroleum, metallurgy, pharmaceuticals, environmental protection, liquor and other industries. Understanding the classification of explosion-proof electrical equipment will help users purchase suitable explosion-proof electrical equipment.

1. Classification by explosion-proof places:

Class I: Electrical equipment underground in coal mines

Class II: Electrical equipment used in all other explosion-proof places except waste mines and underground

2. According to the purpose, it can be divided into:

Explosion-proof lamps, explosion-proof boxes, explosion-proof switches, explosion-proof pipe fittings, explosion-proof buttons, explosion-proof instruments, explosion-proof fans, explosion-proof air conditioners, explosion-proof analysis huts, explosion-proof transformers, explosion-proof cameras, explosion-proof telephones, etc.

3. According to the different test safety gap and ignition current ratio, explosion-proof electrical appliances can be divided into:

Class I: explosion-proof electrical appliances used in methane-mines

Class II, explosion-proof electrical appliances used in explosive gases other than mines

Class IIA: ethane, propane, methanol, propanol, aniline, benzene, gasoline, petroleum, etc.

Class IIB: coke oven gas, ethylene, butadiene, diformaldehyde, etc.

Class IIC: hydrogen, carbon disulfide, etc.

Class IIC has the highest explosion-proof grade and can be applied to Class IIC, IIB and IIA. Class IIB can be applied to Class IIB and IIA.

4. According to the explosion-proof type, it can be divided into:

1. Flameproof type d

Flameproof explosion-proof electrical equipment focuses on flame retardancy. Its shell can withstand the pressure of the internal mixed gas explosion product. The flameproof shell must have good mechanical strength to prevent the explosion inside the shell from breaking through the shell or escaping from the shell. It must be both flameproof and explosion-resistant. The gap in the flameproof shell structure can cool the flame, reduce the flame propagation speed or terminate the acceleration chain, and prevent sparks from escaping from the shell into the surrounding explosive environment. Flameproof explosion-proof electrical is a more classic explosion-proof type with mature technology and long service life. The flameproof type must turn off the power during the maintenance of the explosion-proof shell.

2. Increased safety type e

Increased safety explosion-proof electrical focuses on enhancing the safety of internal electrical equipment. Under normal conditions, sparks, arcs, and dangerous temperatures will not be generated, and further mechanical, electrical, and thermal protection measures will be taken to prevent it from becoming a source of ignition for flammable gases. The heating element must not exceed the temperature, and the use parameters of electrical components must leave room. It is required to increase the electrical clearance and creepage distance, select materials with high insulation grade, reliable electrical connection, eliminate inappropriate mechanical stress, reduce contact resistance, and thus reduce temperature. Improve the protection level, waterproof, dustproof, at least IP54.

3. Intrinsically safe type i

Any sparks, arcs, and thermal effects generated under normal conditions cannot ignite the circuit in the specified explosive gas environment. The electrical parameters of the control circuit must meet the explosion-proof requirements. Reduce voltage, current, and reduce inductance and capacitance parameters. Intrinsically safe can be repaired, but intrinsically safe must be low power, less than 1.3W, and is mostly used for industrial instruments, such as portable combustible gas detectors.

4. Positive pressure type p

Positive pressure explosion-proof cabinet, there is a protective gas in the shell, such as clean air or inert gas nitrogen, to ensure that the internal air pressure is slightly higher than the external air pressure, prevent external explosive gas from entering the shell, and at the same time take away the heat generated by electrical components through sweeping, such as the heat of inverter products, so as to achieve the purpose of ventilation and cooling, and extend the service life of electrical appliances.

5. Sand-filled type q

Filled with sand, quartz or glass particles, the ignition source and the combustible environment are isolated, so that under the specified conditions of use, the arc or high temperature generated in the shell cannot ignite the surrounding explosive gas environment. .

6. Oil-filled type o

The oil-filled explosion-proof type is to immerse the entire equipment or parts of the equipment in oil (protective liquid) so that it cannot ignite the explosive gas environment above the oil surface or outside the shell.

7. Casting type m

Electrical equipment or components are sealed in a sealant so that they cannot ignite the surrounding explosive mixture.

8. Airtight type h

Explosion-proof equipment with a good airtight shell.

9. Spark-free type n

Under normal operation, no arc or spark is generated, and the overheating temperature will not ignite the surrounding explosive mixture. It belongs to Class II electrical equipment and is not suitable for underground coal mines.

10. Dust explosion-proof type DIP

Prevents combustible dust from entering the shell, divided into dustproof shell and dust-tight shell.