It can be known from several basic conditions of combustion that extinguishing fire is the process of destroying combustion conditions to terminate combustion reaction. Its basic principles are summarized as follows: cooling, asphyxiation, isolation and chemical inhibition.
1. Cooling and extinguishing: For general combustionsone of the conditions for sustained combustion is that they reach their respective ignition temperatures by the action of flame or heat. Therefore, in the case of a general combustible fire, the combustion reaction will be discontinued if the combustible is cooled below its ignition or flash point. The extinguishing mechanism of water is mainly cooling.
2. Extinguishing by suffocation: the combustion of any combustible must be carried out above its minimum oxygen concentration, otherwise the combustion cannot continue. Therefore, by reducing the oxygen concentration around the burning material can play a role in extinguishing the fire. Commonly used carbon dioxide, nitrogen, water vapor and other fire extinguishing mechanism is mainly asphyxiation.
3. Isolation extinguishing: Isolation of the combustible from the ignition source or oxygen causes the combustion reaction to cease. In a fire, close the relevant valves and cut off the flow to the combustible gas and liquid in the ignition area; Opening the relevant valves to pipe liquid combustibles from containers that have already burned or are threatened by the fire to a safe area is an isolating fire-extinguishing measure.
4. Chemical suppression extinguishing: is the use of fire extinguishing agent and chain reaction of intermediate radical reaction, so that the chain reaction of combustion to interrupt the combustion can not continue. The main extinguishing mechanism of the commonly used dry powder extinguishing agent and halogenated alkyl extinguishing agent is chemical suppression.
