Explosion-proof requirements for compressed air room

The explosion-proof requirements for compressed air rooms need to be comprehensively constructed from multiple dimensions such as environmental assessment, equipment selection, system configuration, and operation management. The following is an analysis of the technical points:

1. Environmental risk assessment and layout specifications

1. hazardous area classification: The explosion risk area classification of the machine room needs to be carried out in accordance with GB50029 -2003 “Code for Design of Compressed Air Stations”. If there are combustible dust, volatile gases or high-temperature working areas around the machine room, they should be designated as key explosion-proof areas and explosion-proof isolation belts should be set up.
2. Building structural requirements: The wall of the machine room shall be equipped with a firewall with a fire resistance limit of not less than 2 hours, and the floor shall be paved with an anti-static and non-ignition floor. Doors and windows must have explosion relief functions, and the explosion relief area is calculated according to the standard of 0.05m²/m³ to ensure that the pressure can be released in a directional manner when an explosion occurs.
3. ventilation system design: Explosion-proof axial flow fans should be used for forced ventilation, and the number of air changes should not be less than 12 times/hour. The air inlet needs to be equipped with a three-stage filter device, including primary filter, medium filter bag and high efficiency filter, to ensure that the cleanliness of the incoming air meets the ISO 8573-1 Class 2 standard.

2. Selection standards for explosion-proof equipment

1. Host equipment requirements: The air compressor must be oil-free screw type or centrifugal type to avoid lubricating oil participating in the three elements of explosion. The motor needs to be flameproof type (Exd IIB T4), and a safety factor of 1.2 times needs to be considered for power matching.
2. Auxiliary equipment configuration: The air storage tank should be made of special steel for pressure vessels, and the design pressure should be at least 30% higher than the working pressure. The piping system needs to use seamless stainless steel pipes (304 and above material), and the radius of curvature of the elbow is not less than 3DN to reduce turbulence.
3. Security accessory configuration: Explosion-proof pressure transmitters, temperature sensors and gas concentration monitors must be installed. When it is detected that the concentration of combustible gas reaches 25% of the lower explosive limit, the system shall automatically activate the sound and light alarm and cut off the power supply.

3. Construction of electrical explosion-proof system

1. Distribution system requirements: Power cables need to be copper conductor crosslinked polyethylene insulated cables, and the cross-section current carrying capacity is selected according to 1.5 times the rated current. Cable trays shall be stepped explosion-proof trays, and the grounding resistance shall not exceed 4Ω.
2. Lighting System Specifications: Explosion-proof LED lamps should be used for machine room lighting, with an illumination of no less than 200lx. Emergency lighting needs to be of self-contained battery type, and the continuous power supply time is not less than 90 minutes.
3. Lightning protection and grounding measures: An independent lightning protection grounding grid needs to be set up, and the spacing between grounding electrodes shall not be less than 5 meters. All metal equipment casings and pipe flanges need to be connected at equal potential through jumper wires.

4. Operation and maintenance management system

1. Daily inspection procedures: Each shift needs to check the equipment operating temperature (not exceeding 180℃), pressure fluctuation (±0.05MPa) and vibration value (≤7.1mm/s). Drain condensate from the air storage tank every day and test the efficiency of the oil-water separator.
2. Regular maintenance plan: Clean the air filter every 2000 hours of operation and check the tightness of the air valve. The main engine needs to be overhauled every 8000 hours of operation, focusing on testing key parameters such as bearing clearance and rotor clearance.
3. emergency response plan: It is necessary to formulate a special emergency plan for explosion accidents, clarify evacuation routes and initial fire rescue procedures. Organize no less than 2 special explosion-proof drills every year to ensure that personnel master 100% emergency response skills.

5. Response plan for special working conditions

1. Response to high temperature environment: When the ambient temperature exceeds 40℃, the backup cooling system needs to be activated to ensure that the compressor inlet temperature does not exceed 45℃.
2. Dust environmental protection: In dusty places, it is necessary to add a cyclone separation device to the air inlet and shorten the air filter element replacement cycle to 500 hours.
3. Corrosive gas treatment: If corrosive gases are detected, immediately switch to nitrogen protection mode and passivate the piping system.

Through the implementation of the above technical measures, a complete explosion-proof system for the compressed air machine room can be built. In actual projects, risk assessment needs to be carried out based on specific process conditions. It is recommended to entrust a professional organization to conduct an evaluation of the current situation of explosion-proof safety every three years and continuously improve protective measures.