After heptafluoropropane fire extinguishing, the concentration of HF decomposition products is too high, corroding data center servers and precision electronic equipment.
Heptafluoropropane gas fire extinguishing systems are widely used in important locations such as data center power distribution rooms. The HF hydrogen fluoride produced by the decomposition of its extinguishing agent at high temperatures is highly corrosive and requires special attention in design and use. Section 3.1 of GB 50370-2005 provides comprehensive provisions for system design requirements. GB 18614-2012 requires the extinguishing agent purity to be no less than 99.6%.
Heptafluoropropane design concentration 8% to 10% for computer rooms and other electronic equipment rooms 8% to 9% for libraries and archives 9% to 10%. Discharge time more than 95% discharged within 10 seconds. Soaking time more than 10 minutes for solid fires and more than 5 minutes for electrical fires. The agent weight is calculated based on the protected zone volume, design concentration and temperature correction factor. HF is produced by decomposition above 350 degrees Celsius and is positively correlated with the fire source temperature.
HF concentration safety limit short-term exposure 5-minute limit 5 ppm. Measures to reduce HF include ensuring rapid fire extinguishing within a 10-second discharge time to lower the fire scene temperature, reasonably designing the concentration to avoid overfilling, and controlling the types of combustibles in the protected zone. After extinguishing, it is recommended to install a forced ventilation system that starts exhaust 10 minutes after extinguishing to discharge HF gas. Precision equipment should undergo HF residue testing after extinguishing.
The system composition includes storage cylinders with specifications of 40 L, 70 L, 100 L, 120 L, activation cylinders driven by nitrogen, selector valves configured for multiple protected zones, nozzles of the total flooding type arranged evenly, and seamless steel pipe DN25 to DN80. The fire resistance rating of the cylinder room shall be no less than Grade II, with explosion venting openings provided, and the venting area calculated at 0.01 to 0.02 square meters per cubic meter. Pipeline airtightness test at 1.15 times the pressure held for 3 minutes.
Check the storage cylinder pressure gauge monthly at approximately 2.5 MPa at 20 degrees Celsius to see whether it is within the green zone. Check pipeline connections and nozzles quarterly. Weigh the heptafluoropropane every six months; if the loss exceeds 5%, replenishment is required. Conduct a full linkage test annually. Conduct hydrostatic tests of storage cylinders every five years. After each activation, the storage cylinder must be replaced or refilled, and the pipeline must be checked for residual matter. Electrical equipment should be provided with waterproof covers to prevent condensation water.
The ceiling in the protected zone should be able to withstand the impact pressure of the extinguishing agent discharge, approximately 10 to 20 Pa. Doors of the protected zone should open outward to facilitate entry after extinguishing. For precision electronic equipment, it is recommended to conduct HF residue testing after extinguishing using the wipe cloth method or ion chromatography. Engineering experience shows that reasonably controlling the design concentration and ensuring rapid discharge are the keys to preventing and controlling HF corrosion.
In the application of heptafluoropropane gas fire extinguishing systems in hotel data centers and power distribution rooms, in addition to routine maintenance and testing, attention should also be paid to the sealing maintenance of the protected zone. Air-conditioning duct wall penetrations, cable tray openings, gaps under doors, etc. are common leakage points; the sealing condition should be checked at least once a year and repaired promptly. The temperature of the cylinder room should be controlled within the specified range; high temperatures will cause the cylinder pressure to rise, and low temperatures will cause the pressure to drop, affecting the discharge effect. The solenoid valve and mechanical activation device of the system activation cylinder should be checked quarterly to avoid sticking due to long-term inactivity. The hotel engineering department should establish an inspection and maintenance ledger for the gas fire extinguishing system, recording the items, data and operators of each inspection to ensure the system is always in a usable state. The periodic hydrostatic testing of system cylinders and extinguishing agent refilling should be entrusted to qualified professional units; after refilling, a sealing test should be conducted and the cylinder weight recorded for subsequent weighing comparison.
Design optimization of gas fire extinguishing systems can reduce the risk of HF generation. Choosing a gas extinguishing agent with a lower decomposition temperature, such as IG541 mixed gas, which does not produce decomposition products during extinguishing, is a more environmentally friendly choice. However, IG541 requires a larger number of cylinders and thus more cylinder room space. For small protected zones, high-pressure water mist fire extinguishing systems can also be considered as an alternative. The gas discharge time should be controlled within 10 seconds, the shorter the better; rapid extinguishing can lower the fire scene temperature and control HF generation at the source. Openings in the protected zone should be fully considered at the design stage; all closable openings should be provided with automatic closing devices that activate simultaneously. Electrical equipment in the protected zone should use non-flammable materials to reduce fire load and lower the fire scene temperature and HF generation. The forced ventilation exhaust air volume after system activation should be no less than 6 air changes per hour, and exhaust outlets should be located at the bottom of the protected zone because HF gas is heavier than air. Recovery operations after extinguishing should be performed by trained professionals who enter the protected zone wearing protective equipment to check equipment status. Through reasonable design and standardized operation, the generation and hazards of HF can be controlled at the lowest level.
Design optimization of gas fire extinguishing systems can reduce the risk of HF generation. Choosing a gas extinguishing agent with a lower decomposition temperature, such as IG541 mixed gas, which does not produce decomposition products during extinguishing, is a more environmentally friendly choice. However, IG541 requires a larger number of cylinders and thus more cylinder room space. For small protected zones, high-pressure water mist fire extinguishing systems can also be considered as an alternative. The gas discharge time should be controlled within 10 seconds, the shorter the better; rapid extinguishing can lower the fire scene temperature and control HF generation at the source. Openings in the protected zone should be fully considered at the design stage; all closable openings should be provided with automatic closing devices that activate simultaneously. Electrical equipment in the protected zone should use non-flammable materials to reduce fire load and lower the fire scene temperature and HF generation. The forced ventilation exhaust air volume after system activation should be no less than 6 air changes per hour, and exhaust outlets should be located at the bottom of the protected zone because HF gas is heavier than air. Recovery operations after extinguishing should be performed by trained professionals who enter the protected zone wearing protective equipment to check equipment status. Through reasonable design and standardized operation, the generation and hazards of HF can be controlled at the lowest level. The interface integration of the gas fire extinguishing system with the hotel intelligent systems requires standardized design. The system should provide standard RS485 or TCP/IP communication interfaces to connect with the hotel's building automation system. The interface data transmission should include basic information such as system operating status, alarm signals, fault signals and discharge signals. When the gas fire extinguishing system activates, the building automation system should automatically shut down the air-conditioning and ventilation systems of the protected zone to prevent loss of extinguishing agent. The access control system of the protected zone should automatically unlock before the discharge countdown begins to ensure the personnel evacuation route is unobstructed. The exhaust linkage of the gas fire extinguishing system should start automatically after extinguishing is confirmed, and the exhaust duration should be determined based on the volume of the protected zone and the extinguishing agent concentration. The interface integration scheme of the gas fire extinguishing system should be determined at the design stage and confirmed by the relevant system suppliers through joint sign-off. The commissioning and acceptance of system integration should include three stages: communication protocol testing, data transmission testing and linkage logic testing, to ensure that the collaborative work among systems is normal and reliable.
The interface integration between the gas fire suppression system and the hotel intelligent systems requires standardized design. The system should provide standard RS485 or TCP/IP communication interfaces to connect with the hotel's building automation system. Interface data transmission should include basic information such as system operating status, alarm signals, fault signals, and discharge signals. When the gas fire suppression system activates, the building automation system should automatically shut down the air-conditioning and ventilation systems in the protected zone to prevent suppression agent loss. The access control system of the protected zone should automatically unlock before the discharge countdown begins to ensure unobstructed evacuation routes. The exhaust linkage of the gas fire suppression system should start automatically after fire extinguishment is confirmed. The commissioning and acceptance of system integration should include three stages: communication protocol testing, data transmission testing, and linkage logic testing. Drill management of the gas fire suppression system is an important means of enhancing emergency response capability. An emergency operation drill of the gas fire suppression system should be conducted at least once per year, covering stages such as fire alarm signal reception, protected zone confirmation, personnel evacuation, equipment shutdown linkage, system activation signal confirmation, and post-extinguishment restoration operations. Before the drill, a detailed drill plan should be prepared, specifying the drill objectives, drill procedures, and the division of roles among participants. During the drill, the time and effectiveness of each operation should be recorded to verify whether all functions operate normally. After the drill, a summary evaluation should be conducted to analyze the problems and deficiencies identified during the drill. Operation training for the gas fire suppression system should be combined with drills, deepening operators' understanding of system functions and operating procedures through hands-on practice. Linkage drills of the gas fire suppression system can verify whether the linkage functions with other systems such as air-conditioning, ventilation, and access control are correct. Through regular drills and training, the emergency response capability of operators and the overall reliability of the system are continuously improved.
Drill management of the gas fire suppression system is an important means of enhancing emergency response capability. An emergency operation drill of the gas fire suppression system should be conducted at least once per year, covering stages such as fire alarm signal reception, protected zone confirmation, personnel evacuation, equipment shutdown linkage, system activation signal confirmation, and post-extinguishment restoration operations. Before the drill, a detailed drill plan should be prepared, specifying the drill objectives, drill procedures, and the division of roles among participants. During the drill, the time and effectiveness of each operation should be recorded to verify whether all functions operate normally. After the drill, a summary evaluation should be conducted to analyze the problems and deficiencies identified during the drill and formulate improvement measures. Operation training for the gas fire suppression system should be combined with drills, deepening operators' understanding of system functions and operating procedures through hands-on practice. Linkage drills of the gas fire suppression system can verify whether the linkage functions with other systems such as air-conditioning, ventilation, and access control are correct. The annual maintenance cost of the gas fire suppression system accounts for approximately 3% to 5% of the system cost. The maintenance contract should specify the content, frequency, and standards of maintenance, as well as the time limits and responsibilities for fault response. Through regular drills and training, the emergency response capability of operators and the overall reliability of the system are continuously improved.
Drills and training for the gas fire suppression system are key measures to ensure emergency response capability. An emergency operation drill should be conducted at least once per year, covering fire alarm signal reception, protected zone confirmation, personnel evacuation, equipment shutdown linkage, system activation signal confirmation, and post-extinguishment restoration operations. Drill records should be archived for reference and serve as a basis for improvement and optimization. Operation training for the gas fire suppression system should cover relevant personnel from the hotel engineering department and security department, with training conducted at least once per year. Through regular drills and training, the emergency response capability of operators and the overall reliability of the system are continuously improved, ensuring that the gas fire suppression system can be operated correctly in emergency situations to protect personnel safety and property safety.