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Perfluoro vs aerosol, Which is better?

In recent years, the development of fire extinguishing has attracted more and more attention. Among them, Perfluoro fire extinguishing and Condensed aerosol fire suppression system are two widely used products. So what are the advantages and disadvantages of these two products?

1. Combustion mechanism

The essence of combustion is a violent oxidation reaction between combustible materials and oxygen, accompanied by light, heat, and smoke. For flaming combustion, four musts (as shown in the figure) are required, namely the fire tetrahedron. It can be concluded that there are four ways to extinguish fires: removing combustibles, cooling, suffocation and blocking chain reactions.

combustion mechanism

2. Condensed aerosol fire extinguishing technology

a. Condensed aerosol fire extinguishing mechanism

Smoke-like aerosol fire extinguishing media is produced through the oxidation-reduction reaction of the aerosol generating agent. There are metal salts or metal oxides in the generated products, which are condensed into solid particles with a particle size of about 1 μm, which meets the requirement that the particle size for Brownian motion is less than 4 μm. Because it may have good diffusivity and is not easy to settle, it can achieve a full Flood to extinguish fire. The fire suppression by hot aerosol fire extinguishing agents mainly includes two aspects: physical suppression and chemical suppression.

The aerosol fire extinguishing agent absorbs heat to a certain temperature in the fire scene. The aerosol particles will vaporize and decompose, further increasing the heat absorption, thus reducing the temperature of the fire scene. The oxidation-reduction reaction generates inert gases such as water vapor, nitrogen and carbon monoxide, which generates water vapor, nitrogen, carbon monoxide and other inert gases in the fire scene. to suffocation.

Aerosol fire extinguishing agents can effectively inhibit the combustion chain reaction. The cations formed through decomposition will react with hydrogen free radicals and hydroxyl free radicals, and continuously absorb a large amount of hydrogen free radicals, hydroxyl free radicals and oxygen free radicals, and then cause These active free radicals combine into stable molecules, thereby interrupting the combustion chain reaction and extinguishing the flame. Chemical suppression by thermal aerosol fire extinguishing agents is relatively stronger than physical suppression.

aerosol fire extinguisher working principle

b. Application advantages of condensed aerosol fire extinguishing technology

Since aerosol fire extinguishing agents are generated by the reaction of solid generator redox agents, aerosol fire extinguishing devices have a non-pressure storage structure. By rationally configuring fire retardants and coolants, the intrinsic safety issues of the device can be effectively solved. Due to its non-pressure storage structure, aerosol fire suppression system have the advantages of being lightweight, easy to install, and free of pressure maintenance compared to other pressure storage fire extinguishing devices. They are suitable for use in places where daily maintenance is inconvenient and maintenance is difficult and requires a long period of time. Aerosol fire suppression system application.

Although aerosol fire extinguishing agents have high fire extinguishing efficiency, and their ODP and GWP are both zero, aerosol fire extinguishing agents are non-clean fire extinguishing agents. There will be aerosol residues in the space after the fire is extinguished, which will seriously hinder the escape of people in the fire scene. , so it is not recommended to be used in crowded places, and the cations formed by the decomposition of aerosol fire extinguishing agents are generated through combustion, so there is a certain fire risk and it is not suitable for protecting places where flammable and explosive substances are stored.

3. Perfluoro fire extinguishing technology

a. Perfluoro fire extinguishing mechanism

Perfluoro fire extinguishing agent is mainly used to extinguish fire by removing heat from the fire scene through cooling effect.

After the fire extinguishing agent is released, Perfluoro will quickly vaporize at the fire scene. The vaporized Perfluoro forms a gaseous mixture with air. Its heat capacity is much larger than that of air alone, so it has significant heat absorption capacity. In a suitable system At the design concentration, this mixture of extinguishing agent and air will absorb a large amount of heat in the fire scene and destroy the fire tetrahedral balance.

Secondly, Perfluoro will undergo a pyrolysis reaction in which molecular bonds are broken at high temperatures. Compared with its vaporization endotherm, pyrolysis will absorb more heat. The heat value released in the fire environment will decrease rapidly as the amount of fire extinguishing agent increases, directly causing the combustion zone to cool down and reduce it to the temperature at which the flame is extinguished.

The pyrolysis reaction of Perfluoro will generate free radicals that inhibit the combustion chain reaction, thus interrupting the combustion chain reaction and extinguishing the flame. Therefore, Perfluoro ‘s fire suppression mainly includes two aspects: physical suppression and chemical suppression. In low-temperature fire extinguishing (that is, early fire extinguishing), physical suppression is mainly used, while in high-temperature fire extinguishing, physical suppression is mainly combined with chemical suppression and fire extinguishing.

b. Application advantages of Perfluoro fire extinguishing technology

Perfluoro fire extinguishing agent leaves no residue after release and leaves no traces after extinguishing the fire. It is suitable for use in fire extinguishing situations with high cleanliness requirements.

Due to the NOVEL value of the Perfluoro fire extinguishing agent (NOAEL concentration: refers to the maximum concentration of the fire extinguishing agent that cannot observe physiological reactions caused by the toxic effects of the fire extinguishing agent) and the LOAEL value (LOAEL concentration: refers to the physiological effects of the toxic effects of the fire extinguishing agent that can be observed The minimum concentration of the reactive fire extinguishing agent) is greater than 10%, and the fire extinguishing concentration of Perfluoro fire extinguishing agent is 4% to 6%, which is about half of its NOVEL value of 10%. After protection according to the fire extinguishing design concentration, there is still a certain safety margin.

However, Perfluoro will produce harmful substances HF and Perfluoro (COF2) due to thermal decomposition during fire extinguishing. COF2 is unstable and easily reacts with moisture in the air to generate HF and CO2. HF is a highly toxic and corrosive substance recognized worldwide. Extensive contact with it is highly irritating and corrosive to the skin, and can cause severe burns to the human body.

4. Perfluoro vs aerosol

Perfluoro vs aerosol
Perfluoro vs aerosol

Perfluoro vs aerosol, they have their own advantages and disadvantages. Different types of fire extinguishing devices are suitable for different occasions and situations. When selecting a fire extinguishing device, comprehensive consideration and analysis must be conducted based on the actual situation to ensure that the selected fire extinguishing device can achieve the best fire extinguishing effect.