Combustion is a REDOX reaction of luminescence, heat, flame and smoke, and the combustion of substances must meet three necessary conditions,
that is, combustible, accelerant and fire source. Modern science has found that for some complex combustion, there is a fourth condition - the chain reaction.
Once these conditions are destroyed, the combustion will stop, which is the basic starting point of the fire extinguishing agent.
Basic methods of fire suppression:
Isolation method: the combustibles and combustibles and fire sources are separated;
Asphyxiation method: dilute the concentration of oxidant;
Cooling method: reduce the temperature of the fuel, so that it is reduced to below the ignition point;
Chemical suppression method: Break the chain reaction.
Classification of fire extinguishers:
Classified according to fire extinguishing principle
Physical extinguishing agent: water, foam, carbon dioxide
Chemical extinguishing agent: dry powder, alkyl halide
According to the material form
Gas extinguishing agent: carbon dioxide, alkyl halide
Liquid extinguishing agent: water, foam, 7150
Solid fire extinguishing agent: dry powder, G-1 powder
The foaming properties of surfactants can be used to make fire extinguishing agents. The main functions of surfactants in foam extinguishing agents are foaming and extinguishing. Due to the cooling effect of the water contained in the foam, as well as the foam layer, micellar film or gel layer covered on the surface of the flame,
the fire and oxygen isolation, and play a fire-fighting role. Generally high carbon fatty acids or high carbon alcohols anionic, non-ionic and amphoteric active agents
with high foaming power.
The type of foam extinguishing agent is different, and the surfactant used is also different.
Fluoroprotein foam fire extinguishing agent is based on ordinary egg self-foam fire extinguishing agent, adding fluorocarbon surfactant, hydrocarbon surfactant, etc.,
to improve its performance. Compared with the common egg self-foam extinguishing agent, the fluidity, oleophobic, fire resistance and compatibility of fluoroprotein
foam are better than that of ordinary protein foam, and the fire extinguishing performance is significantly improved, and the price is similar to that of ordinary protein
foam extinguishing agent.
Water foam fire extinguishing agent is made of fluorocarbon surfactant, hydrocarbon surfactant, foam stabilizer, antifreeze agent, etc., also known as light water foam fire extinguishing agent, foam fluidity is good, fire extinguishing speed is fast, and fire extinguishing efficiency is high. The fluoroprotein type and silicone surfactant type in
the anti-soluble foam extinguishing agent can resist the dissolution and destruction of water-soluble A, B and C liquids by using fluorocarbon surfactants and
Hydrocarbon-hydrocarbon surfactant and fluorocarbon surfactant are added into the gel type anti-soluble foam fire extinguishing agent. The formed foam forms a
film which is neither soluble in water nor solvent on the surface of hydrophilic solvent, and the foam has good stability.
High expansion foam fire extinguishing agent is a synthetic surfactant based foam fire extinguishing agent, its main components are fatty alcohol sodium sulfate, dodecyl alcohol plus antifreeze agent, stabilizer and other additives, foaming times can be up to 1000 times. In addition to foaming, some of the surfactants in the fire extinguishing agent also have foaming stabilization. Good foaming performance is called foaming agent, foaming agent can only have a good foaming ability under stirring, blowing and other conditions. If the foaming performance is good and the foam stability is not good, the resulting foam will not last long. Such as soap and sodium alkyl benzene sulfonate have good foaming properties, but the stability of sodium alkyl benzene sulfonate after foaming is poor. In order to make the generated foam durable and stable, the foam stabilizer must be added. The surfactants that can be used as foam stabilizers include long-chain alkylammonium chloride, fatty acid condensates of non-ionic surfactants, alkyl aryl sulfonates, etc.
Low expansion foam extinguishing agents also need to add surfactants to reduce surface tension to stabilize the foam. This class of surfactants currently specifically uses hydrolyzed protein crosslinked derivative water absorbers. The protein decomposition is dispersed in aqueous solution in the form of spherical microgels, and the hydrophilic groups on the surface are exposed in water. When foam is produced, the hydrophilic microgels are adsorped to a certain extent on the surface to stabilize the foam. Moreover, due to cross-linking and hardening, the foam retains its original shape and achieves isolation. In addition, the water-absorbing agent has the effect of water absorption and humidification, and the water loss in the fire consumes a lot of heat, which increases the fire-fighting effect.