Does coal mine air compressor require explosion-proof

Coal mine air compressor must require explosion-proof the reasons and specific requirements are as follows:

1. explosion-proof necessity: the particularity of coal mine environment

there are a large number of inflammable and explosive substances such as gas and coal dust in coal mine. When the concentration reaches the explosion limit, it is easy to cause explosion accidents when encountering ignition sources such as electrical sparks, high temperature or static electricity. As the key power equipment in the well, the following risks may occur during the operation of the air compressor:

1. electrical spark: If no explosion-proof measures are taken for the motor, electric control device and other components, electric spark may be generated due to short circuit, overload or poor contact.
2. high temperature surface: If the heat generated during compression is not effectively controlled, the surface temperature of the equipment may exceed the ignition point of flammable substances.
3. Mechanical friction: Friction of moving parts (e. g. bearings, gears) may generate high temperatures or sparks.

Therefore, the coal mine air compressor must pass the explosion-proof design, put an end to the ignition source, to ensure the safe operation in the dangerous environment.

2. explosion-proof requirements: standards and specifications

the explosion-proof requirements of coal mine air compressor shall comply with the following national standards and industry norms:

1. explosion-proof marking and certification
   • must be labeled ExdIMb explosion-proof signs, where:
     • “d” represents flameproof type (equipment shell can withstand internal explosion pressure and prevent flame propagation);
     • “I” special for coal mine;
     • “Mb” for explosion-proof grade, suitable for gas environment.
   • Need to provide within the validity period MA coal safety certification(Safety signs for coal mine products), imported equipment must also pass the type inspection of domestic explosion-proof institutions.
2. Equipment structure and performance
   • flameproof Enclosure: The shell clearance shall be ≤ 0.3mm to ensure that the explosion energy does not leak out. The surface roughness is ≤ 6.3 μm to prevent corrosion from damaging the flameproof structure.
   • oil-free lubrication technology: Adopt oil-free lubrication or water lubrication design to avoid oil mist mixed with combustible gas to form an explosive mixture.
   • Explosion-proof, dustproof and waterproof performance: Adapt to the wet and dusty environment underground to prevent the combination of coal dust and oil mist from causing explosion.
   • Temperature control exhaust temperature shall be strictly controlled (such as single screw air compressor exhaust temperature ≤ 100 ℃) to avoid high temperature ignition of gas.
3. Safety accessories and protection devices
   • pressure relief valve A pressure relief valve is installed on the outlet pipeline of the air bag (gas storage tank) to quickly release excess gas when the pressure reaches 1.2 times of the rated value to prevent explosion.
   • Safety valve and drain valve: The air bag must be equipped with reliable safety valve and drain valve, and the pressure data must be checked regularly and recorded.
   • Interlocking device: Equipped with pressure, temperature, oil pressure and other alarm interlocking devices to ensure that the equipment automatically stops when it is abnormal.

3. application scenarios and cases

1. downhole operation power supply
   • provide power for pneumatic rock drills and anchor drilling rigs, and drive the ventilation system to dilute the gas concentration.
   • Case A coal mine adopts explosion-proof screw air compressor, through oil-free lubrication technology, to achieve continuous 24 hours of safe operation, no gas explosion accident.
2. Open-pit mine blasting operation
   • air supply for pneumatic breaking hammers and loaders to avoid operational risks.
   • Case an open-pit coal mine uses an explosion-proof mobile air compressor, equipped with an explosion-proof motor and a sealed cable lead-in device to meet the needs of operations in high-risk areas.
3. Chemical and Pharmaceutical Industry
   • drive pneumatic agitators, valve actuators, or pneumatic conveying systems for aseptic workshops.
   • Case an explosion-proof air compressor is selected in a chemical enterprise to ensure that the compressed air quality meets the process requirements and avoid the risk of explosion through a high-efficiency filtration system.

4. Management and Maintenance Requirements

1. inspection before entering the well
   • the full-time explosion-proof inspector shall check the "explosion-proof certificate MA coal safety certification" and issue the well entry certificate before going into the well.
   • After overhaul, it is necessary to pass the air tightness test (no leakage for 10 minutes under the pressure of 0.2MPa) and the insulation resistance measurement (≥ 1MΩ).
2. Daily inspection and record
   • check the state of flameproof surface, grounding resistance (≤ 2Ω) and action data of protection device in each shift.
   • The detection cycle of high-risk areas (such as coal mining face) is shortened to once a month, and the pressure, temperature and other parameters are recorded in detail.
3. Tools and qualifications
   • use explosion-proof testing tools (such as megohmmeter with Ex certification) in accordance with the new national standard.
   • Inspectors shall pass GB 3836.16-2024 special training and obtain corresponding qualification certificates.