Basic principles of fire fighting
According to the basic conditions of combustion, any combustible produce combustion or continuous combustion must have the necessary and sufficient conditions for combustion. Therefore, after the occurrence of a fire, extinguishing the fire is the process of destroying the burning conditions and stopping the combustion reaction.
Water extinguishing agent.
Water is the most commonly used extinguishing agent. Water can absorb a lot of heat from the burning material, causing the temperature of the burning material to drop rapidly, resulting in the termination of combustion. When water is vaporized under heat, its volume increases by more than 1,700 times. When a large amount of water vapor is enveloped around the combustion object, it can prevent air from entering the combustion area, thus greatly reducing the oxygen content and smothering the combustion due to lack of oxygen.
Gas extinguishing agent
The use of gas extinguishers began at the end of the 19th century. Since the gas extinguisher has the advantages of no pollution and no damage to the protection equipment after being released, its protection objects have gradually expanded to various fields. Due to the wide sources of CARBON dioxide, the use of air isolation after the asphyxiation can be successfully suppressed fire, so the early gas extinguishing agent mainly used carbon dioxide.
Foam extinguishing agent
It is a developing trend that high expansion foam extinguishing system replaces low expansion foam extinguishing system. High-expansion foam extinguishing agent has a high foaming ratio (201-1000 times), which can quickly fill the fire space within a short time. It is especially suitable for extinguishing large-space fires and has the advantages of fast extinguishing speed. Low-expansion foam extinguishing agent mainly covers the surface of the object of fire by foam, isolating the air and extinguishing the fire with water damage loss, so it is powerless to extinguish the fire of liquefied hydrocarbon flowing, underground engineering, ships, valuable instruments and equipment and articles.
Dry powder extinguishing agent.
Dry powder fire extinguishing agent is composed of one or more kinds of small inorganic powder with fire-extinguishing ability, mainly including active fire-extinguishing component, hydrophobic component and inert filler. Particle size and distribution of powder have great influence on fire-extinguishing effect. Asphyxiation, cooling, radiation and chemical inhibition of flame combustion are the concentrated manifestations of the fire-extinguishing efficiency of dry powder. The extinguishing component of dry powder extinguishing agent is the inactive substance of combustion reaction.
