Discussion on the advantages of superfine dry powd

2022-08-02
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Discussion on the advantages of superfine dry powder fire extinguishing agents

summary

most of the fire extinguishing agents used in the last century were Halon 1201 and 1301. At that time, it was considered that Halon 1301 was the best flame inhibitor suitable for various types of fires. However, in the mid-1980s, people gradually realized its impact on the environment, the destruction of the atmospheric ozone layer, and global warming to varying degrees. In 1993, the Montreal agreement was issued in Canada to restrict the production of substances that destroy the ozone layer, and stipulated that the use of such substances would be banned globally by 2005

it has become a top priority to select the extinguishing agent that is quick to react, effective, clean, safe to people, low toxicity and conducive to environmental protection

common substitutes

at present, the known traditional and newly developed Halon Substitutes mainly include ABC dry powder fire extinguishing agent, plant protein aqueous film-forming foam fire extinguishing agent, hot aerosol fire extinguishing agent, heptafluoropropane fire extinguishing agent and fire extinguishing system, carbon dioxide fire extinguishing agent and fire extinguishing system, inert gas fire extinguishing agent (commonly known as "smoke burning out"), water mist fire extinguishing system, etc

according to the fire extinguishing principle, the above fire extinguishing agents and fire extinguishing systems are all physical fire extinguishing agents except heptafluoropropane fire extinguishing agent, hot aerosol fire extinguishing agent and ABC dry powder fire extinguishing agent, which belong to chemical fire extinguishing. In addition to its inherent characteristics, the common characteristics of physical fire extinguishing agents are the problems of slow fire extinguishing speed and low fire extinguishing efficiency

let's focus on the performance comparison between ultra-fine dry powder and other fire extinguishing technologies

comparative advantages

1. Water mist fire extinguishing technology was first developed by a few developed countries, such as Finland, the United States, Canada, etc. The basic principles of fire extinguishing are generally as follows: (1) the gas is cooled to absorb a large amount of heat and quickly reduce the temperature in the flame area (2) asphyxiation: the water mist is injected into the fire site and vaporized into analytical steam, and the gas expands rapidly to remove the air, reducing the oxygen concentration in the combustion area and asphyxiating the fire flame

the environmental protection performance and resource utilization of water mist are very high. As it belongs to physical fire extinguishing, its fire extinguishing speed and efficiency are much worse than that of ultra-fine dry powder fire extinguishing agent. At the same time, water mist has strict requirements on the particle size of water, resulting in higher requirements on the manufacture and use of nozzles. At the same time, As a fire extinguishing agent, it saves the trouble of manual loading and unloading of extensometer and the resulting error. The unique design agent of fully automatic extensometer structure requires absolute stability of water quality and pure water, which brings certain difficulties to the wide promotion

at present, the water mist fire extinguishing system developed at home and abroad requires high system pressure, which correspondingly increases the working pressure of pipeline fittings and water pumps, and also brings corresponding price and technical problems

2. Heptafluoropropane fire extinguishing agent and fire extinguishing system the fire extinguishing principle of heptafluoropropane fire extinguishing agent is similar to halon fire extinguishing agent. It belongs to chemical fire extinguishing and has good fire extinguishing efficiency. Its fire extinguishing efficiency is equivalent to half of halon fire extinguishing agent. However, because the fire extinguishing agent itself contains halogen, it has existed in the air for about 15-20 years. At the same time, a large amount of hydrogen fluoride gas is generated at the fire site, which is combined with gaseous water to form hydrofluoric acid. Hydrofluoric acid is a highly corrosive acid, which has a strong acid corrosion effect on skin, paper, glass and precision instruments

3. Carbon dioxide extinguishing agent and extinguishing system. Fire extinguishing principle of carbon dioxide: it is liquefied under high pressure or low temperature. When it is sprayed, the gas volume expands rapidly and dilutes the protected space. The advantages are: no pollution to the environment during fire extinguishing, no corrosion and damage to the protection area, and it can put out ABC type fires. It can also put out solid deep-seated fires under high concentration. Disadvantages: in practical application, high-pressure system with high-pressure liquefaction storage and low-pressure system with low-temperature storage are usually used. High pressure storage requires a large number of bottle groups, covers a large area, and has strict requirements on the storage environment temperature. The low-pressure system requires external refrigeration equipment, which is expensive and strict with the transportation pipeline

4. The national patented product -------- ultra fine dry powder high efficiency fire extinguishing agent, which was successfully developed by Wuhan green fire fighting equipment Co., Ltd. at the end of 2001, has excellent performance. The excellent fire extinguishing efficiency is reflected in the following three aspects:

1) strong inhibition of flaming combustion

flaming combustion is a chain reaction. Fuel molecules are activated under the high temperature of combustion or the energy formed by them, and free radicals or active genes are generated in the presence of oxygen. These free radicals with high energy propagate reactions to maintain the continuous combustion. When the superfine dry powder is mixed with the flame, the fire extinguishing components quickly capture the combustion free radicals, so that the free radicals are consumed faster than the production speed. The combustion free radicals are quickly exhausted, the chain reaction process is terminated, and the flame is extinguished rapidly

2) strong asphyxiation effect on surface combustion

superfine dry powder has a good rate and efficiency for extinguishing flaming combustion, and has a good extinguishing effect on the surface combustion (smoldering) of general solid substances. When the ultra-fine dry powder crystal powder contacts with the burning surface, a series of chemical reactions will occur, which will melt under the high temperature of the solid surface and form a glass like covering layer to separate the solid surface from the surrounding air and suffocate the combustion

3). Shielding and cooling effect on thermal radiation

when using ultra-fine dry powder to extinguish the fire, the dense cloud like powder is mixed with the flame to decompose the endothermic reaction, which can absorb part of the heat of the flame. Some inactive gases produced by these decomposition reactions, such as carbon dioxide and water vapor, can dilute the oxygen concentration in the combustion area and weaken the combustion reaction of the fire

the fire extinguishing concentration of ultra-fine dry powder fire extinguishing agent has passed the national inspection and can be properly repaired if necessary. The Department inspection is 64.4g/m3. It is one of the fire extinguishing agents that have been invented at home and abroad. The fire extinguishing concentration is the lowest, the fire extinguishing efficiency is the highest and the fire extinguishing speed is the fastest. The fire extinguishing efficiency per unit volume is 2-3 times that of halon fire extinguishing agent, 6-10 times that of ordinary dry powder fire extinguishing agent, more than 10 times that of heptafluoropropane fire extinguishing agent, and 15 times that of carbon dioxide

in addition, the ozone depletion potential (ODP) of ultra-fine dry powder fire extinguishing agent is zero, and the effect potential (GWP) of greenhouse Wiggins and others in hydrogen peroxide and 2 cobalt chloride solution is zero. It has no irritation to human skin and respiratory tract, no corrosion to protectors, non-toxic and harmless. The residue after fire extinguishing is easy to clean, and can be widely used in various production and living places to put out class A, B, C fires and live equipment fires. The fire extinguishing agent is identified by the national science and technology department as the first in China and is currently at the world leading level. (end)

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