As we all know, the substances that can effectively destroy the combustion conditions in the combustion zone, to achieve suppression of combustion or suspend combustion, are called fire extinguishing agents. Generally, we have some basic requirements for fire extinguishing agents, such as high efficiency, easy access, basically harmless to humans and objects, and low cost. At present, the commonly used fire extinguishing agents are water, foam, carbon dioxide, dry powder, haloalkane fire extinguishing agents and so on.
The performance of different types and different types of fire extinguishing agents is different, and if used blindly, it may cause counterproductive results and greater losses. Therefore, firefighters will make correct choices according to the nature, state, burning time, wind direction and wind of the material burning in the fire field, and ensure the supply intensity to ensure that the effectiveness of the extinguishing agent can be fully exerted. So, what are the differences between different fire extinguishing agents on fire extinguishing?
The fire extinguishing principle of foam fire extinguishing agent is much more complicated than that of water fire extinguishing agent. Because the specific gravity of foam is much smaller than that of general flammable liquids (commonly used fire extinguishing foam, the foaming multiple ranges from 2 to 1,000, and the specific gravity is from 0.001 to 0.5), so it can float on the surface of the liquid to form a foam cover. The foam itself has a certain viscosity, which can adhere to the surface of general combustible solids, so as to achieve the corresponding fire extinguishing effects such as blocking, cooling and dilution.
Compared with the principle of fire extinguishing, the classification of foam fire extinguishing agents is more complicated! Because foam extinguishing agents can be classified in different forms according to a variety of situations, such as chemical foam extinguishing agents and air foam extinguishing agents according to the formation mechanism of foam.
Chemical foam is generated by the chemical reaction between two aqueous solutions of two agents, and the gas contained in the foam is carbon dioxide;
Air foam is generated by stirring, and the gas contained in the foam is generally air;
The air foam fire extinguishing agent can be divided into three types of low expansion foam, medium expansion foam and high expansion foam according to their foaming multiples.
Among them, according to the type and use of the foaming agent, the low-expansion foam fire extinguishing agent can be further divided into five types: protein foam, fluoroprotein foam, water-forming foam, solvent-resistant foam and synthetic foam fire extinguishing agent.
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