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Lock Dragon Fire Digital Science Museum-"Foam Fire Extinguishing Technology" (II
Release time:
2021-08-05
The basic composition of foam fire extinguishing agent and its function The foam fire extinguishing agent is usually composed of foaming agent, foam stabilizer, liquid resistant additive, cosolvent and antifreeze, other additives, etc. Fluoroprotein and film-forming foam extinguishing agent also add fluorocarbon surfactant. Foaming agent is the basic composition of foam fire extinguishing agent. The foaming agent of protein foam is hydrolyzed protein of animal hair (mainly pig) and hoof grain (mainly cow). Synthetic foam is various types of hydrocarbon surface active substances, which are commonly used in daily chemicals. Its function is to make the aqueous solution of foam fire extinguishing agent easy to foam. Aqueous film-forming foam fire extinguishing agent foaming agent useful cocoamidopropyl betaine
The Basic Composition and Function of Foam Fire Extinguishing Agent
Foam fire extinguishing agent is usually composed of foaming agent, foam stabilizer, liquid resistant additive, cosolvent and antifreeze, and other additives. Fluoroprotein and film-forming foam extinguishing agent also add fluorocarbon surfactant.
Foaming agent
Foaming agent is the basic composition of foam fire extinguishing agent. The foaming agent of protein foam is hydrolyzed protein of animal hair (mainly pig) and hoof grain (mainly cow). Synthetic foam is various types of hydrocarbon surface active substances, which are commonly used in daily chemicals. Its function is to make the aqueous solution of foam fire extinguishing agent easy to foam. The foaming agent of water film forming foam extinguishing agent useful cocoamidopropyl betaine and alkyl glycoside.
Protein foam stabilizer
Protein foam foam stabilizer is mostly ferrous sulfate (FeSO4), aqueous film foam and high multiple foam foam stabilizer useful ethylene glycol butyl ether. The role of the foam stabilizer is to increase the water holding time of the foam and enhance the stability of the foam.
Fluorocarbon surfactant is a kind of modifier for fluoroprotein foam, which can reduce the surface and interfacial tension of foam, enhance foam fluidity and improve foam oleophobicity. The molecular structure of the "6201" pentamer used in our country in advance is:
The molecular structure of sodium perfluorononyl oxybenzene sulfonate (OBS) is:
Because of its molecular structure, the foam fire extinguishing agent added with the above two fluorocarbon surfactants does not have the conditions for film formation on the surface of oil (hydrocarbon).
The fluorocarbon surfactant in the aqueous film-forming foam is mainly used for fire extinguishing. To determine whether the film-forming foam is film-forming, the surface tension, interfacial tension and diffusion coefficient are used in the national standard "foam fire extinguishing agent" GB15308.
liquid-resistant additive
Liquid-resistant additives are mainly used in anti-dissolving foam (Alcohol-Resistant Foams), generally anti-alcohol polymer compounds (xanthan gum). Its function is to kill water-soluble liquid fires, and the polymer biological polysaccharides in the foam solution can form a film on the surface of the water-soluble liquid to protect the above foam from dehydration and defoaming.
cosolvent and antifreeze
The cosolvent and antifreeze are generally ethylene glycol, ethylene glycol butyl ether, isopropyl alcohol and other alcohols or alcohol ethers, so that the foam extinguishing agent system is stable, the foam is uniform, and the frost resistance is good.
There are also foam improvers, anti-corruption agents, anti-corrosion agents and other additives in the foam fire extinguishing agent.
After all the foam extinguishing agent is mixed into a premixed liquid, the validity period will be greatly shortened, especially the protein foam extinguishing agent, which will soon rot, so it should usually be stored in the original liquid state.
Protein, fluorine protein foam
Protein and fluorine protein foam mainly isolate the combustion liquid from the air through the covering effect of the foam to achieve fire extinguishing. In addition to the covering effect of the foam, the aqueous film foam extinguishing agent can form a protective film with air isolation and cooling effect on the surface of the protected hydrocarbon liquid (oil) due to the low surface tension of the fluorocarbon surfactant used. Its fire extinguishing effect also depends on the firmness of the protective film. Anti-dissolving foam (anti-alcohol foam) is through the anti-alcohol polymer polysaccharide compound (xanthan gum) in the foam to form a layer of polymer film on the surface of the water-soluble liquid to protect the foam from the water-soluble liquid Dehydration caused by defoaming, so as to achieve fire extinguishing.
high multiple foam
High-expansion foam is mainly used to close the fire area through a large number of high-expansion foam in a dense state to block the inflow of new air to suffocate and extinguish the fire. The fire extinguishing mechanism of medium-multiple foam depends on its foaming multiple and its use mode. When a lower multiple is used to extinguish a fire, the fire extinguishing mechanism is the same as that of low-multiple foam; when a higher multiple is used to extinguish a fire in a full-submerged manner, the fire extinguishing mechanism is the same as that of high-multiple foam.
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