Combustion must meet three conditions at the same time: combustible material, combustion-supporting material and fire source. Put the fire out is to destroy the existing burning conditions. As long as one burning condition can be removed, the fire can be extinguished. People have summarized the following basic methods in fire fighting practice.
1. Cooling
Spray the fire extinguishing agent directly on the combustible material to reduce the temperature of the combustible material below the self-ignition point, thereby stopping the combustion, the prevention method of cooling the unburned combustible material with water to prevent it from reaching the ignition point and catching fire.
Use water to extinguish a fire. Its main function is to cool and extinguish a fire. If a fire occurs, water can be used to cool and extinguish a fire.
2. Suffocation
Combustible substances can not burn in the absence of air or the oxygen content in the air is below 14%. The so-called suffocation method is to cut off the air supply of burning materials.
Take appropriate measures to prevent air from entering the combustion zone, or dilute the oxygen content in the air with inert gas, so that the burning material lacks or cuts off oxygen and goes out. It is suitable for extinguishing fires in enclosed spaces, production equipment and containers. When using the suffocation method to fight the fire on the fire scene, use the asbestos quilt, wet sack, wet quilt, sand, foam and other non-combustible or incombustible materials to cover the burning or close the hole, fill with water vapor, inert gas (such as carbon dioxide, nitrogen, etc.) Combustion area, use the original doors on the building and the parts on the production, storage and transportation equipment to close the combustion area to prevent air from entering.
3. Isolation
The combustible matter is one of the most important conditions in combustion conditions. If the combustible matter is isolated from the ignition source or air, the combustion reaction will automatically stop. For example, the method of spraying fire extinguishing agent to isolate combustibles from air and heat, using foam fire extinguishing agent to cover the surface of burning liquid or solid, and separating combustibles from flame and air are all isolations Fire fighting method.
There are many specific measures to isolate and extinguish fires. For example, transfer flammable and explosive materials near the fire source to a safe place; close valves on equipment or pipelines to prevent combustible gas and liquid from flowing into the combustion zone, demolish flammable building structures adjacent to the fire source to prevent the spread of fire Space zone and so on.
4. Suppressing
Inject chemical fire extinguishing agent into the combustion zone to participate in the combustion reaction, so that the chain reaction of free radicals (combustion chain) is stopped, so that the combustion reaction stops or cannot continue. The fire extinguishing agents that can be used in this way are dry powder and halogenated alkane fire extinguishing agents. When extinguishing a fire, a sufficient amount of extinguishing agent should be accurately injected into the combustion zone to prevent the extinguishing agent from blocking the combustion reaction. At the same time, cooling measures should be taken to prevent re-ignition.
