Fire classes
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The fire and fire classes
The decisive element of the fire is the flame that develops in an uncontrolled way in time and in space.
Combustion is a chemical reaction between a body fuel and a combustive agent.
The fuel
È la sostanza in grado di bruciare, in condizioni ambientali normali esso può essere allo stato solido (legno, carta, carbone, ecc. ) , liquido ( petrolio, benzina, alcool, ecc) gassoso
(acetylene, fuel gas, hydrogen, etc.)
The combustive agent
che interviene in un incendio è l’ossigeno presente nell’aria.
Il rischio d’incendio, quindi esiste in tutti i locali.
Flash temperature
È la minima temperatura alla quale il combustibile sviluppa vapori in quantità sufficienti a formare con l’aria una miscela infiammabile.
The range and the flammability limits
The fuel must be present in fixed proportions so that the fuel mixture combustive agent result flammable gaseous state. For every combustible substance exists a range of values, expressed in % by volume of flammable substance in air or in grams of the substance in 1 m3 of air. This field is defined flammable range. Below or above these limits the flammable gas present in the mixture with the combustion gases can not give rise to a combustion.
The ignition temperature
It is the minimum temperature at which the flammable mixture starts to burn spontaneously and continues in combustion without supply heat.
The trigger
It is the element which, in contact with the flammable mixture, starts the combustion reaction. It may be formed from any source of heat:
The fire
it can be represented with a triangle whose three sides are made up of fuel, comburent, heat source. In the absence of one of the three elements, fire does not exist.
Hazard
The greatest danger to people in case of fire may be:
Fire classes
It is necessary to ensure the protection of people:
CLASS A - Fires of combustible solids, flammable and incandescent
Material to be protected - ordinary combustibles such as wood, paper, fabric, plastic, and most kinds of trash
Extinguishing agent - ABC powder; Water; Foam
CLASS B - Fires of liquid materials for which you need a hedge effect and choking
Material to be protected - Alcohols, ethers, paints and solvents, mineral oils and fuels, vehicles
Extinguishing agent - ABC powder; Foam;Carbon dioxide(CO2)2)
CLASS D - chemicals spontaneously combustible in the presence of air, inactive in the presence of water or foam with the formation of hydrogen and explosion hazard
Material to be protected - Alkylated aluminum, barium peroxide, sodium, magnesium, and manganese, potassium, aluminum powder, potassium peroxide
Extinguishing agent - D powder, Carbon dioxide
CLASS E - Fire of electrical equipment under voltage
Material to be protected - ransformers, alternators, panels and switches, electric motors, telephone systems
Extinguishing agent - Carbon dioxide2)
CLASS F - Fires involving cooking hobs
Material to be protected - Kitchens, canteens, restaurants and working with presence of animal and vegetable fats
Extinguishing agent - Foam class F