subota, 26. travnja 2008.

fire in the city


Chemical reaction

The fire tetrahedron
Fires start when a flammable and/or a combustible material with an adequate supply of oxygen or another oxidizer is subjected to enough heat and is able to sustain a chain reaction. This is commonly called the fire tetrahedron. No fire can exist without all of these elements being in place.
Once ignited, a chain reaction must take place whereby fires can sustain their own heat by the further release of heat energy in the process of combustion and may propagate, provided there is a continuous supply of an oxidizer and fuel.
Fire can be extinguished by removing any one of the elements of the fire tetrahedron. Fire extinguishing by the application of water acts by cooling the fuel to stop the reaction whilst also starving the fire of oxygen. Whereas application of carbon dioxide is intended primarily to starve the fire of oxygen. Other gaseous fire suppression agents, such as halon or HFC-227, interfere with the chemical

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