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Comparison between IG-541 and heptafluoropropane gas fire extinguishing system: environmental protection, safety and adaptability


2015-11-12


Gas fire extinguishing system is one of the four traditional fixed fire extinguishing systems (water, gas, foam, dry powder) and is widely used. In recent years, in order to protect the atmospheric ozone layer and maintain the human ecological environment, the Montreal Convention agreement has been signed, and the most traditional and commonly used Halon gas fire extinguishing system has been banned. At this stage, heptafluoropropane fire extinguishing system, IG-541 gas fire extinguishing system and carbon dioxide fire extinguishing system can be selected for the communication room.
Due to the suffocating effect of carbon dioxide, while spraying, it often causes serious damage or even death to the personnel staying in the protection area, and also produces a huge greenhouse effect. Therefore, from the perspective of "people-oriented" and environmental protection, the use of carbon dioxide fire extinguishing system is not recommended in the newly-built communication room.
Nowadays, many kinds of gas fire extinguishing agents have been developed to replace Halon, such as chemical synthesis and inert gas. Among them, heptafluoropropane and IG541 mixed gas fire extinguishing agent are widely used in Halon alternative gas fire extinguishing system in China, and have been used for many years, with good results and accumulated some experience.
The advantages and disadvantages of heptafluoropropane fire extinguishing system and IG541 gas fire extinguishing system are briefly introduced below.
1. From the perspective of environmental protection
The impact of fire extinguishing agents on the environment mainly has the following three index requirements: ① the ozone layer destruction potential ODP is zero; ② The greenhouse effect potential GWP is zero or very low; ③ The survival life ALT in the atmosphere is smaller.
Comparison of environmental impact of fire extinguishing agents
Name of extinguishing agent ODP GWP ALT / A
Heptafluoropropane (FM200) 0.6 31
IG-541 (cigarette burning out) 0
According to the figures in the left table, the environmental protection of heptafluoropropane and IG-541 meet the existing environmental protection requirements, and the three values of IG-541 are zero, so IG-541 is slightly better in environmental protection.
2 safety considerations
Safety comparison to human body (Toxicity Comparison):
Toxicity comparison table
project
Name cup combustion method concentration (% v / V) design concentration (% v / V) NOAEL (% v / V) LOAEL (% v / V)
Heptafluoropropane (FM200) 5.8 9.0 10.5
IG-541 (burning out) / 37.5 43.0 52.0
NOAEL: the highest concentration without observed adverse reactions.
LOAEL: is the lowest concentration at which harmful effects can be observed.
It can be seen from the above table that the maximum concentration of non-toxic reaction of heptafluoropropane system is 9%, the minimum concentration of toxic reaction is 10.5%, and the design concentration is 8%. The three values are very close, so once there is a slight error in design and construction, the concentration during fire extinguishing may reach the concentration range of toxic reaction. Therefore, the design concentration of heptafluoropropane system should be strictly controlled. The three values in the above table of IG-541 system differ greatly, so the control of concentration is relatively inaccurate, so it is relatively easy in design and calculation. In addition, the heptafluoropropane fire extinguishing system produces severe poisons under high temperature conditions, has pungent smell and is corrosive to the equipment, which is also the reason why it must be released in 10 seconds.
3. Adaptability to the size of protection area:
According to the Guangdong provincial standard code for design of heptafluoropropane (HFC-227ea) clean gas fire extinguishing system (dbj15-23-1999), it is stipulated that "when using pipe network fire extinguishing system, the area of a protection area shall not be greater than 500m2 and the volume shall not be greater than 2000m3". Due to the high working pressure of IG-541 system, the Shanghai local standard "technical specification for inert gas IG-541 fire extinguishing system" dg / tj08-306-2001 cancels the control of the size of the protection area. Therefore, when the protected area is large space, large span and more than 800m2, IG-541 fire extinguishing system is more suitable for buildings. The working pressure of heptafluoropropane is low, and the nozzle pressure at the most unfavorable point is not less than 0.8MPa, and the length of pipe network is strictly controlled. Therefore, the adaptability of IG-541 fire extinguishing system is much wider than that of heptafluoropropane.
4 Summary
IG-541 fire extinguishing system and heptafluoropropane fire extinguishing system can have good performance and can meet the uninterrupted operation in the protected area. Through the comparison and demonstration of the above aspects, IG-541 fire extinguishing system has certain advantages in transmission distance. However, IG-541 must be stored at 15MPa high pressure, which has high requirements for the pressure and safety of steel pipes and pipelines and valves before decompression. The pressurization pressure of the storage container of heptafluoropropane system is 4.2mpa, which is much smaller than that of IG-541 system. Therefore, heptafluoropropane system has certain advantages in the safety of steel cylinders and pipelines. Therefore, no matter which system is finally selected, it should be determined after comprehensive comparison. It can only be used with the consent of the competent department of public security and fire control.