Are there explosion-proof requirements for ventilation in the air compressor room

Code for explosion-proof management of ventilation system in air compressor room

As the core area of industrial power, the air compressor room must be designed to strictly follow safety regulations. According to the current safety production standards and equipment operating characteristics, enterprises should implement explosion-proof management of ventilation systems in accordance with the following requirements:

1. Judgment basis for explosion-proof requirements

1. Media risk assessment
   • If the air compressor is lubricated with mineral oil and there is a possibility of oil mist accumulating in the machine room, it is necessary to design protection in accordance with explosive dust environments (Area 21).
   • When using oil-free air compressors, the risk of hydrogen accumulation caused by compressed air condensate emissions still needs to be evaluated.
2. Environmental classification standards
   • According to the “Code for the Design of Electrical Installations in Explosive Hazardous Environments”(GB50058), the level of release sources of combustible substances in the machine room determines the protection requirements:
     • Continuous-level release source: An overall explosion-proof ventilation system needs to be set up, with air changes ≥12 times/hour.
     • Primary release source: The local exhaust device covers the release area, and the fresh air volume is replenished ≥3 times/hour.

2. Core parameters of ventilation system

1. Ventilation efficiency requirements
   • Main ventilation system: Adopt mechanical air supply and exhaust method to maintain a slight indoor negative pressure (-5 to-10Pa) to prevent combustible gases from escaping.
   • Accident exhaust device: Linkage with the combustible gas detector, full-volume ventilation can be completed within 10 minutes. The motor needs to be explosion-proof type.
2. air distribution design
   • The air supply outlet should be arranged in the lower part of the room, and the exhaust outlet should be arranged at the top to form a directional air flow to prevent harmful substances from staying.
   • When the ventilation pipe passes through the firewall, a fire damper and pressure monitoring device need to be set up, and it will be automatically closed under abnormal conditions.

3. Explosion-proof technical measures

1. Equipment selection specifications
   • Electrical equipment such as ventilators and motors should be of Exd IIBT4 and above explosion-proof grade, and the cable threading tube should be sealed.
   • The flange connections of metal air pipes need to be bridged to ground, and the electrostatic grounding resistance is ≤100Ω.
2. Daily monitoring requirements
   • Check the air volume and pressure of the ventilation system every month to ensure that the ventilation efficiency meets the design value.
   • The combustible gas detector is verified quarterly, the detection response time is ≤30 seconds, and the alarm value is set to 25% of the lower explosion limit.

4. Emergency management mechanism

1. Accident handling plan
   • Formulate the “Emergency Plan for Explosion in the Air Compressor Room” to clarify evacuation routes and initial fire rescue procedures.
   • It is equipped with explosion-proof axial flow fans as emergency exhaust equipment and stored in a special cabinet outside the machine room.
2. maintenance system
   • Clean up dust on ventilation louvers and filter screens every month, and check the dynamic balance of fan blades.
   • Conduct ventilation system interlock function tests every six months to verify the reliability of emergency exhaust devices.

5. Key points of compliance review

1. Design stage: Ventilation system drawings must be reviewed by an institution with pressure piping design qualifications and stamped with a special GC2 design seal.
2. Acceptance stage: Entrust a CMA certification testing agency to implement the acceptance test of the explosion-proof ventilation system and issue a qualified test report.
3. Operation stage: Establish a ventilation equipment maintenance ledger and keep maintenance records and test reports for at least 5 years.

Enterprises should establish a full-process management and control system of “risk assessment-system design-acceptance test-operation and maintenance” to ensure the intrinsic safety of the ventilation system in the air compressor room through professional and institutionalized management. It is recommended to entrust a professional organization to implement an evaluation of the current situation of explosion-proof safety every three years and dynamically update risk management and control measures.