Fire Extinguisher

         In the last blog, I explained in detail what fire is and what different classes of fire are. Now I explained how to control fire, the type of fire extinguisher, and how it works.

    There is no single method to extinguish the fire. It largely depends on the class of fire, fuel involved, the site, and the size of the fire. Based on these criteria different firefighting techniques will be required.

    As we already know in the fire triangle 3 elements are required for occurring fire Oxygen fuel and heat. To extinguish a fire is largely a matter of depriving the fire of one or more of these factors, so methods of extinguishing the fire can be classified in terms of removing these factors.

All fires can be extinguished by,        

1.          Smothering
2.          Starving
3.          Cooling  

        1. Smothering:- 

            If the oxygen supply to the burning material can be sufficiently reduced, burning will cease. 

        The general procedure is to help fresh air from reaching the seat of the fire, allowing the combustion to reduce the oxygen content in the confined atmosphere until it extinguishes itself, for example by

•Smelling out candles

• Smothering a visage with a fire mask
• Belting a person in a fire mask

 Smothering can also be achieved by removing the oxygen in the atmosphere, therefore extinguishing the fire by carbon dioxide and inert gas.

2. Starvation:-

         In some cases, a fire can be extinguished simply by removing the energy source. This may be fulfilled in several ways, similar to stopping the inflow of liquid or gassy energy,

removing solid energy in the path of the fire, or allowing the fire to burn until all of the energy is consumed. 

3. Cooling:-

         One of the most common ways of extinguishing a fire is by cooling it with water. This process depends on cooling the fuel to a point where it doesn't have sufficient vapor to burn, with the reduction in temperature-dependent on the application of an adequate flow of water to establish a negative heat balance.                                                      To extinguish a fire by cooling, the rate at which heat energy is lost from the burning material must be increased by removing some of the heat energy. This reduces the temperature of the burning mass, reducing the heat release rate. Ultimately, the fire will die down.
      Water is a good cooling agent because of its high thermal capacity and idle heat of vaporization. This, combined with the fact it's available in large amounts, makes it by far the most extensively useful fire extinguishing agent.

Type of fire extinguisher

Water Extinguishers:-

        Suitable to be used on class A solid combustible fires (wood, paper, fabrics, coal) water fire extinguishers penetrate burning materials, creating a cooling effect and stopping re-ignition.

       It shouldn't be used for kitchen fires, fires caused by flammable gas and liquids as well as fires that involve electrical equipment. 

        Water fire extinguishers have a red label and a class A rating. 

Foam extinguishers:-

       Foam fire extinguishers are often used on Class A and B fires. They're most suited to extinguishing liquid fires like petrol or diesel and are more versatile than water extinguishers because they will even be used on solids like wood and paper. The foam extinguishes liquid fires by sealing the surface of the liquid, creating a cooling effect, preventing flammable vapor from reaching the air, and starving the fire of fuel. They're not suitable for use on free-flowing liquid fires. 

        Foam extinguishers have a cream label. Foam extinguishers are needed by businesses and premises where the building is created from various organic materials or in buildings where such organic materials are likely to be found including warehouses, residential properties, hospitals, schools, offices, and buildings storing flammable liquids.

Carbon dioxide extinguishers:-

          CO₂ extinguishers are ideal for places with lots of electrical equipment like offices or server rooms because they're safe to use on fires involving electrical apparatus. CO₂ extinguishers don't leave any residue, unlike foam extinguishers. They'll even be used on Class B fires, those involving flammable liquids such paraffin or petrol. CO₂ extinguishers work by smothering the fireplace and setting apart the availability of air. 

        Carbon Dioxide Extinguishers (CO₂) has a black label. 

Dry Powder extinguishers:- 

        Dry Powder extinguishers are good multi-purpose fire extinguishers because they'll be used on Class A, B, and C fires. They will even be used on fires involving electrical equipment however, they are doing not cooling the fireplace so it can re-ignite. Powder extinguishers also can create a loss of visibility and should create breathing problems. They're not generally recommended to be used inside buildings unless there's absolutely no alternative. 

        Powder extinguishers have a blue label.

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