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A flame is a mixture of reacting gases and solids emitting visible, infrared, and sometimes ultraviolet light, the frequency spectrum of which depends on the chemical composition of the burning material and intermediate reaction products.
Fires can be extinguished by water, fuel or oxidant removal, or chemical flame inhibition; though, because fires are classified depending on the elements involved, such as grease, paper, electrical, etcetera, a specific type of fire extinguisher may be required. The classification is based on the type of fires that the extinguisher is more ...
Essential factors in sustaining a fire make up the "fire triangle" Fire control is the practice of reducing the heat output of a fire, reducing the area over which the fire exists, or suppressing or extinguishing the fire by depriving it of fuel, oxygen, or heat (see fire triangle).
This is commonly accomplished by chemical reactions that reduce the flammability of fuels or delay their combustion. [1] [2] Fire retardants may also cool the fuel through physical action or endothermic chemical reactions. Fire retardants are available as powder, to be mixed with water, as fire-fighting foams and fire-retardant gels.
Gaseous fire suppression, also called clean agent fire suppression, is the use of inert gases and chemical agents to extinguish a fire. These agents are governed by the National Fire Protection Association (NFPA) Standard for Clean Agent Fire Extinguishing Systems – NFPA 2001 in the US, with different standards and regulations elsewhere.
Chemical foam is a stable solution of small bubbles containing carbon dioxide with lower density than oil or water, and exhibits persistence for covering flat surfaces. Because it is lighter than the burning liquid, it flows freely over the liquid surface and extinguishes the fire by a smothering (removal/prevention of oxygen) action.
In closed premises, they are effective regardless of the location and height of the fire. This can be contrasted with dry chemical systems, which must be directly aimed at the flame. In open spaces, they are reasonably effective when targeting the top of the fire, unlike gaseous and dry agents which must be directed at the base of the flames.
Whereas dry chemical systems must be directly aimed at the flame, condensed aerosols are flooding agents and therefore effective regardless of the location and height of the fire. Wet chemical systems, such as the kind generally found in foam extinguishers, must, similarly to dry chemical systems, be sprayed directionally, onto the fire.