【 Weak current College 】 gas extinguishing system selection

Summary: adoption of various gas fire extinguishing systems and fire extinguishing agents and chemical characteristics of the analysis of the gas fire extinguishing systems for the workplace and reasonable selection configuration.

Keywords: gas fire extinguishing systems; alternatives; selection; engineering applications

1. Overview

Gas extinguishing system refers to the usual extinguishing agent to liquid, liquefied or gaseous state stored in pressure vessels, fire-fighting with gas (including steam, mist) injection as a fire extinguishing system for the media. And in the protection zone space formation in all directions are a gas concentration, but at least be able to keep the fire extinguishing concentration reaches specification requirements of immersion time, fight the protection area of the space, 3D fire.

In the early 1980s experts study shows, including halon fire extinguishing agent, CFC substances in atmospheric emissions that would lead to the atmospheric ozone layer destruction, the living environment of mankind, in June 1990 in the United Kingdom London from 57 countries jointly signed the Montreal Protocol (Amendment), decided to phase out the production and the progressive restriction of the use of freon, halon fire extinguishing agent.

Our June 1991 joined the Montreal Protocol (Amendment), the States parties undertook to cease production of halon 2005 1211 fire extinguishing agent, 2010 to stop production of halon 1301 fire extinguishing agent. And in 1996 promulgating the Chinese fire industry halon phase-out plan as a whole.

Since 1996, alternatives and the rapid development of alternative technologies, just a few years, heptafluoropropane, inert gas mixture (hereinafter IG-541), Chlorotrifluoromethane and other fire extinguishing systems have appeared, the 2003 People's Republic of China Ministry of public security issued the gas fire extinguishing system and component performance requirements and test methods "(GA400-2002), on heptafluoropropane, Chlorotrifluoromethane, IG-541, IG-55, IG-01, such as fire suppression system IG-100 production, inspection made clear.

This article on a variety of gas fire extinguishing systems and fire extinguishing agents and chemical characteristics of the analysis of the gas fire extinguishing system of the Shi

-Use the site and its reasonable selection configuration.

2. performance comparison

At present, in the engineering application of technology is more mature gas extinguishing system: high pressure CO2, heptafluoropropane, Chlorotrifluoromethane, IG-541 four fire extinguishing system, following on the four fire extinguishing system from fire effects, environmental performance, to protect the objects of the destructive, personnel security, safe concentration calculation, project cost and technical maturity analysis.

1. fire effect

Fire extinguishing concentration should result, extinguishant, fire extinguishing speed measured in three aspects.

Table 1 comparison of fire-extinguishing system performance indicators Chlorotrifluoromethane heptafluoropropane high-pressure carbon dioxide IG-541 atmospheric pressure boiling point (° c)-82.1-16.4-56.6-320.0 fire suppression mechanism of physically (reduce the oxygen concentration, cooling) physically part of the chemical way physically (reduce the oxygen concentration, cooling) physically (reduce the oxygen concentration) injection time (s) A class of fire extinguishing concentration 10106060 hazardous surface fire 15% 5.8% 36.47% 28.1% n-heptane 12% 6.6% 20.6% 29.1% design fire extinguishing concentration range 15.6% ~ 19.5% 8 ~ 10% 34 ~ 75% 36.5 ~ 43.9% extinguishant (kg/m3) 0.542 ~ 0.7110.634 ~ 0.811.0 ~ 3.30.47 ~ 0.56m3/m3 fabulous fire up the most comprehensive assessment of the best good slowly worst poor


Chlorotrifluoromethane physically fire, heptafluoropropane physically fire main, the way some chemical fire extinguishing, Chlorotrifluoromethane is liquefied gases, liquid heptafluoropropane genera (nitrogen booster), spray on the protective zone of a cooling effect, but Chlorotrifluoromethane due to low boiling point, its own vapour pressure spray, spray on faster, the dilution effect of the concentration of oxygen is also noticeable.

High-pressure carbon dioxide, IG-541 are physically fire, high-pressure carbon dioxide injection on time on protection zones with reduced oxygen concentration and obvious cooling effect, dilution protection only to IG-541 district of oxygen concentration in the implementation of fire extinguishing suffocation.

2. environmental performance

International measurement of environmental protection is the key indicators on atmospheric ozone depletion potential (ODP), the greenhouse effect (GWP), fire extinguishing agent in the atmosphere of life (ALT). From the perspective of the protection of the ozone layer, first requires the use of extinguishing agent ODP value is less than 0, or 0.05 second request GWP and ALT values as small as possible.

Heptafluoropropane, Chlorotrifluoromethane although the ODP value is 0, the GWP values higher, atmospheric live life long, greenhouse effect, and together with the carbon dioxide is the Kyoto Conference resolution on the framework Convention on climate change (d.c.m) into a controlled area, but due to its very few extinguishant, the overall environmental impact is not big, not too many people. Carbon dioxide is a global environment, the greenhouse effect, the biggest culprit as greenhouse gas fire extinguishing agent's own environmental performance is poor. IG-541 extinguishing agent from nitrogen, argon and small amounts of carbon dioxide gas composition, thermal decomposition will not occur, the extinguishing agent from the atmosphere, with no impact on the environment, in the case of the "green" environmental products. But after a high temperature, nitrogen component is involved in a chemical reaction that produces NO, NO2, and other harmful substances.

Table 2 comparison of the environmental performance of fire-extinguishing system performance indicators Chlorotrifluoromethane high-pressure carbon dioxide heptafluoropropane IG-541ODP value 0000GWP value evaluation 1.3210.40ALT value 267120310 good better best

3. to protect the objects of destructive

Communications room, computerThe room is the conductance of precision equipment, and cleaning of all require very high, the extinguishing agent in fire generated by high temperature decomposition of substances, as well as the impact of the high pressure gas and liquefied gas evaporation induced "dew" and "cold" and "cold hardening" phenomenon, on the protection of the metal surface, circuit boards, chips, etc. can produce different degrees of harm, in protection of precision equipment and precious belongings should pay special attention.

Three fluorine methane, heptafluoro are fluorinated compounds, flame produced by heat decomposition of hydrofluoric acid (HF), protection of objects of metal, glass surface will produce corrosion, the number of generated hydrofluoric acid and pharmaceutical itself, the size of the fire, the fire duration.

High-pressure carbon dioxide injection-and-drop process, because the liquid and solid "dry ice" rapid vaporization, protective zone temperature drops dramatically, to protect the objects have a certain degree of "cold" and "cold hardening effect".

IG-541 extinguishing agent are inert gas, heating does not react, but pressure orifice plate and pipe design should be strictly used by national authorities to conduct an audit of calculation software and radial or bezel nozzle, otherwise will result in a high pressure air flow, a threat to the protection of the object. In the current calculation software for foreign monopoly situations, should not be blindly rely on subjective imagination design promotion.


Table 3 on protected objects of the destructive fire extinguishing system performance indicators Chlorotrifluoromethane high-pressure carbon dioxide heptafluoropropane IG-541 acid decomposition (ppm) 3001000 ~ 30000 residues influences 0000 other slightly chilled cold stress, cold hardening slightly chilled exists the risk of high pressure air flow impact evaluation best poor poor

4. personnel security

Fire spews threat personnel safety after comes mainly from three aspects: the effects of hypoxia, poisoning,.

Whether caused a major decision to fire extinguishing suffocation concentration, the concentration of carbon dioxide and oxygen concentration, fire extinguishing concentration higher, fire extinguishing agent release, the protection zone, the lower the oxygen concentration (less than 12%), the more prone to personnel hypoxia, carbon dioxide concentration is too high (more than 5%) will affect the person's breath, dangerous, carbon dioxide concentrations exceeding 20%, will soon cause poisoning reaction, resulting in hypoxic apnoea. Pharmaceutical toxicity from toxic chemical itself and decomposition of toxicity. Influence escape mainly reflected in the extent reduce fogging protection area of visibility.

Table 4 comparison of fire-extinguishing system for personnel safety performance indicators Chlorotrifluoromethane high-pressure carbon dioxide heptafluoropropane IG-541NOAEL (%) 504943LOAEL (%) > 50510.552LC50 (%) > > 8062ALC 6520 (%) 6530 > > > 80 62 toxic micro virus asphyxia poisoning comprehensive evaluation of low toxicity and non-toxic best worst than good NOAEL — refers to the physiological effects of no adverse reactions the most high. LOAEL — refers to the physiological effects of adverse reaction of minimum concentration. LC50 — refers to rodents exposed 4 hours during half of the deaths of extinguishing agent concentration. ALC — refers to rodents exposed 4 hours during the approximate concentration of about death.

High-pressure carbon dioxide fire extinguishing concentration due to fire suppression system, easily lead to staff; and hypoxia asphyxia on carbon dioxide injection due to the heat absorption when, rapid gasification resulting from frostbite, have the effect of the "white fog" evacuation, the prohibition of the use in some places.

IG-541 pharmaceutical itself non-toxic, does not produce toxic decomposition, according to the United States scientists "low oxygen conditions of life sustaining theory" has proved that the air contains 3% to 5% of the carbon dioxide can stimulate the body's respiratory rate of speed. IG-541 extinguishing join 8% carbon dioxide, which can be played in anoxic conditions that stimulate breathing acceleration, meet the human body in hypoxic conditions of oxygen demand, on the human body is relatively safe, but when IG-541 concentration exceeding 52%, according to the provisions prohibiting ISO14520 NFPA-2001 and use in some places. At the same time as the system pressure is high, the spray-and-drop will produce some noise and dust generation high-speed air flow, lightweight materials, effects of auditory and Visual.

Heptafluoropropane, Chlorotrifluoromethane toxic chemical itself, but the resulting hydrofluoric acid decomposition of some toxicity, with strong pungent odour, stimulating human respiratory and eye, in contrast, Chlorotrifluoromethane pharmaceutical toxicity far below heptafluoropropane, amount of hydrofluoric acid is less than seven perfluoropropane, personnel security.

Ministry of public security and public energy (2001) 217, man made clear: carbon dioxide fire extinguishing system cannot be used to protect the often someone places, three fluorine methane, IG-541 heptafluoropropane, often it can be used to protect.

Any kind of gas fire extinguishing agent on human life has some kind of threat, just a different level of risk, security is relative. Therefore, in some places, even if the choice of three fluorine methane, IG-541, heptafluoropropane these can be used to protect the often someone places gas fire extinguishing systems, system design must also be on each protection area to carry out the necessary concentration calculation (especially IG-541, heptafluoropropane design fire extinguishing concentration and the LOAEL value very close to), ensures the practical spray on the extinguishing agent after the protective area of concentration in the LOAEL value following allowed, the system is running you should set the system status in manual start, avoid system mistakenly spraying causing personnel's injury, at the same time, should be based on the actual situation at the scene, leaving enough of not less than 30s delay startup time, makes it easy for people to flee the scene of the fire.

5, secure checking concentration

In peacetime it was the duty of using gas fire extinguishing system, the actual design concentration should not be longer than the NOAEL value, if the actual design of the concentration between NOAEL value and the LOAEL value, in accordance with the provisions and ISO14520 NFPA-2001 should provide certain measures (such as the number of configured enough escape masks), limited staff and extinguishing agent contact time not exceeding 5min.

7-1)Perfluoropropane, Chlorotrifluoromethane's actual design concentration (C%) use the following calculation formula.

C%=WS/(V+WS）

Heptafluoropropane: S = 0.1269 0.000513 × T (T = 20 ° c)

Chlorotrifluoromethane: S = 0.3164 0.0012 × T (T = 20 ° c)

2) actual design concentration IG-541 (C%) use the following calculation formula.

ln(100/100-C)=WS/VS，C%=1－10－WS/VS

IG-541：S=0.65799+0.00239×T(T=20℃)

VS = 0.706 (20 ° c)

Special attention should be paid to the distribution system in combination in between multiple protection area, individual protection area is not extinguishant systems single cylinder storage medium of multiples, and actual fire extinguishing time is based on the entire amount of extinguishing agent storaged, which spews would create individual protection area of the actual design concentration significantly exceed the NOAEL value, especially the NOAEL heptafluoropropane (9%) and the LOAEL value (10.5%), the NOAEL value IG-541 (43%) and the LOAEL value (52%) is very close to, if not attention, will exist when you accidentally sprayed causing casualties of danger.

6. project cost

Gas extinguishing systems engineering cost includes extinguishant, equipment costs, network costs, storage bottles between the four most space occupied, measure a system's cost should be considered.

High-pressure carbon dioxide, more storage bottle IG-541, bottle footprint with large among area; heptafluoropropane and trifluoromethane storage bottle quantity less storage bottle footprint small area between the different parts of the country, consumption levels, cost per square metre between the bottle in the $ 5000 ~ 20000. The following table 4.1, table 4.2 10000 Yuan/㎡.

Different types of protected objects, gas fire fighting systems engineering construction costs are also different, of the following press 1000m3 archives, libraries and the communications, computer 1000m3 room as an example for cost comparison. The gas fire extinguishing systems engineering cost as described in the table 4.1, table 4.2.

Table 4.1 gas extinguishing system of project cost

(Protected objects as archives, library and repository) cost index Chlorotrifluoromethane high-pressure carbon dioxide heptafluoropropane IG-541 extinguishant (kg) 7102250851450m3 storage cylinders (a) 13541543 storage bottles between area（㎡） 7.224819.2 equipment cost ($) 27.331.635.231.0 network cost ($) 2.01.52.01.5 engineering investment (million yuan) costs between 29.333.137.232.5 storage bottles ($) 7.224.08.019.2 early total investment (million) investment evaluation most 36.557.145.251.7 minimum or low high

Table 4.2 gas extinguishing system of project cost

(Protected object for communication, computer room) cost index Chlorotrifluoromethane high-pressure carbon dioxide heptafluoropropane IG-541 extinguishant (kg) 5421500666400m3 storage cylinders (a) 10361239 storage bottles between area（㎡） 6176.817.6 equipment cost ($) 21.020.233.128.3 network cost ($) 2.01.52.01.5 engineering investment (million yuan) costs between 23.021.735.129.8 storage bottles ($) 6.017.06.817.6 early total investment (million) investment evaluation lowest low 29.038.741.947.4 high maximum

Note: fire extinguishing agent storage cylinder press 70 liter high pressure seamless cylinders, in accordance with the relevant national rules of high pressure vessels, high pressure seamless cylinders service life is 30 years, welded steel cylinder service life of 15 years. Provided by: GB5099 heptafluoropropane fire extinguishing systems at 50 ℃, the extinguishing agent storage cylinder pressure of work for 5.3MPa, welded cylinders should not be adopted. But the manufacturers for interest-driven, almost all with welded cylinders for accuracy, all by seamless cylinders. Equipment, pipeline cost at the current average market prices.

7. technical maturity

Currently, high-pressure carbon dioxide extinguishing systems from fire extinguishing agent, product, design, construction and acceptance have national standards or specifications, technology is more mature. 1929 United States enacted the world's first carbon dioxide extinguishing systems standards, CO2 fire-extinguishing system in the Western countries rapidly, quickly became second only to water fire suppression system's second-largest fire extinguishing system.

Have been enacted and the formal establishment of the national carbon dioxide fire extinguishing system specifications are as follows:

The CO2 extinguishing agent "— GB4396-84

The carbon dioxide fire suppression systems and components of General technical conditions "— GB16669-1996

The CO2 fire-extinguishing system design code — GB50193-93 (1999 revised edition)

The gas fire extinguishing system construction and acceptance of law — GB50263-1997

Heptafluoropropane, IG-541, Chlorotrifluoromethane fire extinguishing system is only in recent years of the new product, the domestic technology relatively immature. The current state of this only a portion of product standards, design specification is not yet mature, system design elementary basis in some parts of the standard and enterprise standard, design of normative, correctness, reliability improvement.

Especially IG-541 fire extinguishing system, owing to compressible gas-phase flow, network computing more complex system design error may be caused by pipe rupture, protective zone of high pressure, request design precision moreHigh, manual calculation almost impossible, system design must be a dedicated computer design software, foreign enterprises for technology blockade of domestic this product is greatly restricted.

Already enacted on halon alternative extinguishing systems for international or foreign standards are as follows:

The gas fire extinguishing system – physical performance and system design (ISO14520: 2000)

The extinguishing fire extinguishing system standards "(NFPA2001: 2000)

Have been enacted and are based on halon alternative extinguishing system of the country, industry or geographical specifications are as follows:

The gas fire extinguishing system and component performance requirements and test methods "— GA400-2002

The heptafluoropropane (HFC-227ea) clean gas fire-extinguishing system design code — DBJ15-23-1999

The inert gases IG-541 extinguishing system technical specification for "— DG/TJ08-306-2001

The chlorotrifluoromethane (HFC-23) clean gas fire-extinguishing system design and construction and acceptance of law — DB45/T88-2003

The halon alternative extinguishing system design and construction and acceptance of law — DB45/T ※ ※-2004

3. a project application

To sum up, when the protection object to archives, library and repository, choose heptafluoropropane, Chlorotrifluoromethane fire extinguishing system is more economic and reasonable; when the protection object to the communication, computer room, a choice of three heptafluoropropane, methane, IG-541 fire extinguishing system is more economic and reasonable; when the protection object to the generator room, transformation and distribution Chamber, choose Chlorotrifluoromethane, high-pressure carbon dioxide extinguishing systems are more economic and reasonable; from the perspective of economic, security, protection of objects for the generator room, transformation and distribution Chamber, choose Chlorotrifluoromethane extinguishing system more economic and reasonable.

Chlorotrifluoromethane fire extinguishing system has not destroyed the atmospheric ozone layer, fire extinguishant is fast, small, micro, low system cost, stable performance, cannot be used in some places, etc., there is a better value, is the most ideal halon substitutes.

Reference documents:

(1) the gas fire extinguishing system – physical performance and system design "— ISO14520: 2000.

(2) the extinguishing fire extinguishing system standards "— NFPA-2001: 2000.

(3) the CO2 equipment specifications · design and installation of — Vds2093-1983.

(4) the heptafluoropropane (HFC-227ea) clean gas fire-extinguishing system design code — DBJ15-23-1999.

(5) the inert gas IG-541 extinguishing system technical specification for "— DG/TJ08-306-2001.

(6) the chlorotrifluoromethane (HFC-23) clean gas fire-extinguishing system design and construction and acceptance of law — DB45/T88-2003

(7) the further enhancement of halon substitutes and alternative technology management: notice of public energy (2001) 217, man.