As a form of fire extinguishing, gas fire extinguishing is widely used in the market because of its excellent performance and fire extinguishing efficiency. However, as a chemical product, gas fire extinguishing system also has its dangers, which is normal. And we cannot ignore the two major hazard sources. Today, we will explain the two major hazard sources that gas fire extinguishing equipment needs to pay attention to. When we use gas fire extinguishing later, we also need to pay attention to it. However, we start from the understanding of the equipment. Gas fire extinguishing equipment produced by regular manufacturers do not need to worry about the safety of the equipment.
These two major sources of danger, one is the risk of gas overpressure; The second is the risk of asphyxiation and toxicity.
The fire resistance rating of the building shall not be lower than grade II, and the relevant regulations and the storage regulations of pressure vessels shall have an exit directly leading to the outdoor or evacuation walkway. The ambient temperature of the storage room and the protection area equipped with the prefabricated fire extinguishing system is -10 to 50 ℃, and the ambient temperature of the storage device of the high-pressure carbon dioxide fire extinguishing system is 0 ℃ to 49 ℃.
1、 Risk of gas overpressure and preventive measures:
1. During the use of gas cylinders, the pressure resistance of the cylinder may be affected by external pollution and internal media.
2. Gas cylinders must be inspected in strict accordance with relevant standards. Steel cylinders that have reached the retirement age must be scrapped, which should comply with the provisions of the regulations on safety and technical supervision of gas cylinders (tsgr0006-2014). There are strict regulations on cylinder marks (steel seal marks), scrap life, periodic inspection cycle, inspection marks and qualification requirements, "supervision regulations on cylinder safety technology".
3. For the safety regulations on handling, loading, unloading, storage and use of gas cylinders, please refer to the relevant regulations of the safety regulations on handling, loading, unloading, storage and use of gas cylinders (gb/t34525-2017).
4. The charging pressure of the prefabricated fire extinguishing system set in the protection area shall not be greater than 2.5 MPa.
5. For IG541 mixed gas fire extinguishing system and other similar systems, the storage device is in a long-term high-pressure state, and the requirements for the storage room are more strict. In addition to meeting the requirements of general storage room, it also meets the relevant national regulations on the storage of high-pressure containers.
6. When the combined distribution system is started, the selector valve should be opened before or at the same time as the container valve.
7. The storage device of the pipe network fire extinguishing system should be set in the special bottle storage room. The bottle storage room is close to the protection area.
8. The storage device is arranged to facilitate operation, maintenance and avoid sunlight. The distance between the operation surface and the wall or between the two operation surfaces shall not be less than 1.0m and 1.5 times of the outer diameter of the storage container.
Second, asphyxiation and toxicity risks and corresponding preventive measures:
1. Among all gaseous fire extinguishing agents, the safety risk of carbon dioxide is relatively large, mainly the risk of suffocation. When the concentration of carbon dioxide exceeds 10%, it will lead to coma, but the design concentration of carbon dioxide fire extinguishing equipment is at least 34%. Therefore, the carbon dioxide total flooding fire extinguishing system is not recommended to be used in places where there are people. In particular, places such as basements do not use carbon dioxide. Carbon dioxide is heavier than air, which will increase the difficulty of ventilation after spraying.
2. Under normal circumstances, the fire extinguishing design concentration of heptafluoropropane and IG541 will not be higher than the NOAEL concentration. At a reasonable concentration, heptafluoropropane and IG541 are non-toxic and suffocating risk.
The design and construction personnel must master the requirements of non-toxic reaction concentration and toxic reaction concentration of gas fire extinguishing agent. The actual use concentration of fire extinguishing design concentration in the manned protection area is not greater than the toxic reaction concentration.
3. The protection area shall have passages and exits to ensure the evacuation of personnel within 30s.
4. The evacuation passages and exits in the protection area shall be provided with emergency lighting and evacuation indication signs. Fire audible alarm shall be designed in the protection area, and flash alarm can be added when necessary. The entrance of the protection area is equipped with fire audible and visual alarms, fire extinguishing agent spray indicator lights and signs of the corresponding gas fire extinguishing system in the protection area. The fire extinguishing agent discharge indicator signal is maintained until the protection area is ventilated, and then it is released manually.
5. The door of the protection area should be opened in the direction of evacuation and can be closed automatically; It is mainly used for evacuation. The door must be able to be opened from the protection area.
6. The protection area after fire fighting shall be ventilated. The underground protection area and the above ground protection area without windows or fixed window sashes shall be equipped with mechanical exhaust devices, and the exhaust outlet shall be set at the lower part of the protection area and directly lead to the outside. The ventilation rate of communication machine room, electronic computer room and other places shall not be less than 5 times per hour.
7. The manual control and emergency operation of the fire extinguishing system shall have warning displays and measures to prevent misoperation.
8. Air respirators should be equipped in places with gas fire extinguishing systems.
9. For the total submerged carbon dioxide fire extinguishing system, other gas fire extinguishing protection areas with fire extinguishing design concentration or actual use concentration greater than the concentration of non-toxic reaction shall be equipped with manual and automatic control conversion devices. When personnel enter the protection area, the fire extinguishing system can be switched to manual control mode; The automatic control mode can be restored when the personnel leave. Display devices for manual and automatic control status shall be set inside and outside the protection area.
10. When the automatic control startup mode is adopted, there is a controllable delay injection of no more than 30s according to the needs of personnel safely evacuating the protection area; For the protection area where no one works at ordinary times, it is set to spray without delay.
11. The door of the bottle storage room should be opened outward, and emergency lighting should be set in the bottle storage room; The bottle storage room should have good ventilation conditions. The underground bottle storage room should be equipped with mechanical exhaust devices, and the exhaust outlet should be set at the lower part, which can be discharged outdoors through the exhaust pipe.
12. For the storage containers where the carbon dioxide fire extinguishing system does not have natural ventilation conditions, a mechanical exhaust device is set between the storage containers. If the height of the exhaust outlet from the ground between the storage containers is not more than 0.5m, the exhaust outlet should be directly led to the outside. The normal exhaust air volume should be determined by the number of air changes of not less than 4 times /h, and the accident exhaust air volume should be determined by the number of air changes of not less than 8 times /h.
