It is the first defense line to fight fires. These cannot be used to extinguish any kind of fire; each of them has a label describing the kind of fire against which it can be used. Fires vary by distance, spreading speed and size in regards to which a person can approach to without danger.
Every kind of extinguisher is designed to fulfill determined functions. These are:
C_ Flammable liquids
K_ Commercial cooker
Fire extingwisher put out fires by:
1_ cooling the burning material
2_ reducing the oxigen quantity up to unable combustion
3_ for the chain reaction of combustion
Water extinguishers mainly put out fire by refrigeration action. The steam that is produced when the water gets in contact with the burning material also helps to prevent more oxygen arrival. When it is applied as a shower on a flammable liquid the extinction effect is achieved thanks to the following factors: oxygen cooling and exclusion.
It is not suitable to extinguish fire in flammable liquids by means of gushes and it is not recommended for electrical installations fire extinction.
Foam extinguishers: fire extinction by oxygen exclusion, suppression of combustible steaming and by refrigeration.
On flammable liquids fire the foam acts as a barrier preventing oxygen to come in and simultaneously it builds a wet layer to unable the liquid vapourization.
Chemical dust extinguishers put out fire by combination of several actions.
Thrown away dust stratifies interrupting the molecular vapour-oxygen combustion: it reduces the oxygen available for combustion and it directly absorbs past of the heat by means of its fine solid particles.