News Center
Your current location：Home > News CenterNews Center
Introduction to the Fire Protection System of Cleanrooms
2025/10/29
1）. Design Principles of Fire Protection Systems in Cleanrooms
1. Safety first: It is necessary to respond quickly to fires (early detection), effectively extinguish them, and ensure the safety of personnel evacuation at the same time.
2. Compatibility principle: The fire protection system must not disrupt the air cleanliness of the clean room (such as avoiding residual fire extinguishing agents and dust accumulation in pipelines), temperature, humidity and pressure difference control.
3. Targeted adaptation: Select the fire extinguishing medium and detection method based on the process characteristics of the clean room (such as whether there are flammable solvents or precision equipment);
4. Interlocking coordination: It needs to be interlocked with the air conditioning and ventilation system of the clean room and the process equipment system (such as cutting off the air conditioning and stopping the equipment operation in case of fire).
2）. Core System Composition
Fire detection system: Emphasizing "early detection and accuracy"
Most fires in cleanrooms are caused by electrical faults (such as short circuits in equipment) or the combustion of flammable materials (such as organic solvents). In the early stage, the fire is concealed and spreads rapidly, which requires a highly sensitive detection system.
Air-sampling smoke detectors (air sampling type) : They are the preferred detection equipment for clean rooms. Air samples are actively drawn through pipelines and sent to the analysis unit for smoke particle detection. The sensitivity can reach 0.001% obs/m (100 to 1000 times that of ordinary smoke detectors), and it can alarm in the early stage of fire (smollowing period), making it suitable for early intervention.
Installation points: The sampling points should cover the key areas of the clean room (such as areas with dense equipment, inside the ceiling, and in the mezzanine under the floor). The sampling tubes should be made of smooth stainless steel (to avoid dust accumulation), and the opening direction should avoid strong air currents (such as air conditioning supply outlets) to prevent interference with sampling.
Auxiliary detection equipment
Temperature detector: When used as a supplement near high-temperature equipment (such as ovens and heating furnaces), explosion-proof type (if there are flammable materials) should be selected, and the casing should be seamless (to prevent dust accumulation).
Flame detector: It is designed for open flames caused by flammable liquids (such as ethanol and acetone) or gas leaks. It has a fast response speed (in milliseconds) and is suitable for open areas (such as wafer storage areas).
2. Fire extinguishing system: "Clean, efficient, and low-damage
It is necessary to avoid using fire extinguishing agents that can pollute the environment and damage equipment (such as water-based and dry powder), and give priority to clean gas or local precise fire extinguishing methods.
Clean gas fire extinguishing system (mainstream choice) : It is suitable for core clean areas (such as production workshops and equipment rooms). The fire extinguishing agent is colorless, odorless, non-conductive and leaves no residue. Production can be resumed quickly after fire extinguishing. Common type: FME-200 (heptafluoropropane) : High fire extinguishing efficiency (fire extinguishing concentration 7-10%), no damage to the ozone layer, suitable for places with people (low toxicity), but it should be noted that the storage cylinders should be placed in non-clean areas (such as equipment interlayers), and the pipelines should be made of stainless steel (anti-corrosion and reduce dust accumulation).
IG-541 (inert gas, composed of nitrogen, argon and carbon dioxide) : Pure natural components, completely volatilize after extinguishing, leaving no residue. It is suitable for scenarios sensitive to chemical residues (such as biomedical clean rooms), but the extinguishing concentration is relatively high (37-43%), requiring a larger gas storage capacity.
CO₂ fire extinguishing system (use with caution) : It has a high fire extinguishing efficiency, but high concentrations (>9%) can cause suffocation. It is only suitable for unattended enclosed areas (such as gas cylinder rooms and waste material rooms), and must be equipped with strict personnel evacuation linkage (such as sound and light alarm + delayed start).
Local fire extinguishing system: For high-risk equipment (such as coating machines, organic solvent storage tanks), "point-to-point" fire extinguishing is adopted:
Small clean gas fire extinguishers (such as portable FM-200 fire extinguishers) facilitate rapid manual response;
Automatic spray-foam combined system (for auxiliary areas only) : If there are areas in the clean room where water is allowed to enter (such as corridors, changing areas), it can be used, but closed nozzles must be adopted (to avoid dust accumulation), and the pipelines need to be treated for anti-corrosion (such as stainless steel).
Prohibited systems: Dry powder fire extinguishing (residual pollution equipment), ordinary water spray (damaging cleanliness, short-circuiting equipment), halogenated alkanes (obsolete, damaging the ozone layer).
3. Smoke exhaust and evacuation system: Suitable for confined environments
Due to the pressure difference control (usually positive pressure) and high sealing performance of clean rooms, smoke is prone to accumulate. Therefore, it is necessary to design smoke exhaust and evacuation plans in conjunction with the air conditioning system.
Smoke exhaust system
Linkage with the air conditioning system: In case of fire, immediately turn off the air conditioning supply/exhaust fans (to prevent the airflow from fanning the fire), start the dedicated smoke exhaust fan, and expel the smoke through the smoke exhaust outlet (the location should avoid the core production area, such as the top of the corridor or the mezzanine). Pressure difference coordination: During smoke exhaust, it is necessary to maintain a positive pressure in the evacuation passage (to prevent smoke from entering). The pressure difference between the clean area and the evacuation passage can be adjusted through the pressure relief valve. Evacuation system
Emergency lighting: Use dust-proof, water-proof and seamless clean type lamps (such as IP65 grade), with illuminance ≥5lux (for evacuation passages) and ≥30lux (for safety exits). Evacuation indication: The signs should be resistant to cleaning (can be wiped with alcohol), and ground fluorescent indications should be added in areas with dense equipment (to avoid being blocked by equipment). Passage design: Evacuation passages should avoid equipment clusters, with a width of no less than 1.1m, and the distance from the entrance of the clean room should comply with the regulations (for example, the distance from the farthest point to the safety exit should be ≤30m).
3）. Special Design Requirements
1. Clean compatibility of pipelines and equipment
Fire protection piping: Prioritize the use of 304/316 stainless steel (anti-corrosion and dust-free), with welded joints (to prevent dust accumulation in the gaps of threaded connections), and the pipe slope should be ≥0.002 (to prevent water accumulation). The equipment casing: Detectors, nozzles, lamps, etc. should adopt seamless design (such as integrated molding), with smooth surfaces (Ra≤0.8μm), which is convenient for regular cleaning (such as alcohol wiping). 2. Interlocking logic with the air conditioning system
When a fire occurs, the system needs to be linked in the sequence of "detection and alarm → cutting off the air conditioning damper → turning off the supply/exhaust fan → starting the fire extinguishing system → opening the smoke exhaust" to avoid the air conditioning airflow interfering with the fire extinguishing or spreading the smoke. 3. Cleanliness standards for maintenance and inspection:
Detector cleaning: Blow the sampling tube with compressed air (Class 5 clean air), and avoid using a wet cloth (which may introduce microorganisms). Gas fire extinguishing system inspection: When conducting leakage inspections annually, operations should be carried out during non-production periods to prevent residual fire extinguishing agents from affecting the products. Simulation test: Prioritize the use of "chemical-free linkage test" (such as only triggering alarms and starting and stopping equipment) to minimize interference with the clean environment.
4）. Typical Scenario Examples
Electronic cleanrooms (such as chip workshops) : In the core area, air-aspirating smoke detectors and IG-541 gas fire suppression are used, while in the auxiliary area (corridors), closed nozzles are employed. The pipes are all made of stainless steel and are shut down in conjunction with the FFU (Fan Filter Unit).
Biomedical cleanroom (such as vaccine workshop) : FM-200 fire extinguishing (no chemical residue) is adopted. Detectors need to be protected from microbial contamination (with an antibacterial coating on the surface). The exhaust system is linked with the pressure difference of the clean area (to ensure that smoke does not invade the production area).
In conclusion, the core of a cleanroom fire protection system is to "achieve the greatest safety at the lowest cost" - it must not only meet fire protection standards but also adapt to the special requirements of clean processes. It is necessary to balance the compatibility between safety and production through the combination of precise detection, clean fire extinguishing, and coordinated linkage.
