Extinguishing a Fire

Combustion and Flame I - Concepts
Class - 8th ISO Subjects
Concept Explanation

Extinguishing a Fire

Fire can be controlled by removing any one or more of these conditions. A fire extinguisher cuts off the supply of air or brings down the temperature of the fuel or both and controls the fire.

Fire can be controlled and extinguished by :-

1.  Removing any combustible materials near the region of fire.

2.  Cutting off the supply of air by using sand or blanket.

3.  Bringing down the ignition temperature by using water.

Fuel in most cases cannot be eliminated. If for instance, a building catches fire, then the whole building is the fuel.

Fire can be extinguished using water :-

Water evaporates, taking away heat from the fire, which in turn cools down the burning materials below its ignition temperature. However, water is dangerous in most of the cases:

  • When used over electrical fires, as it conducts electricity and can cause danger to the people trying to extinguish the fire.
  • Pouring over burning petrol, kerosene, or diesel: these substances are lighter than water and do not mix with water. As a result, water forms a layer beneath them and the substance continues burning.
  • Carbon dioxide fire extinguisher consist of carbon dioxide filled under high pressure in cylinders. It is not a supporter of combustion .Being heavier than air; carbon dioxide settles down and cut off the supply of oxygen which extinguishes the fire.

    When released from cylinders, CO_2  expands enormously in volume and cools down. So, it not only forms a blanket around the fire, it also brings down the temperature of the fuel.

    Soda Acid Fire Extinguisher :  It contain concentrated solution of sodium hydrogen carbonate and sulphuric acid and in separate compartments.

    .... (More Text Available, Login?)
    Sample Questions
    (More Questions for each concept available in Login)
    Question : 1

    When water is poured over burning wood, the fire goes off. This is because ___________________________

    Right Option : A
    View Explanation
    Question : 2
    Column IColumn II
    A. Spontaneous combustionP. Sulphur dioxide
    B. Supporter of combustionQ. Carbon dioxide
    C. Fire extinguisher  R. Oxygen
    D. Incomplete combustionS. Sodium bicarbonate + concentrated Sulphuric acid
    E. Combustion of coal and diesel    T. Carbon monoxide
     U. Phosphorus



    Right Option : D
    View Explanation
    Question : 3

    Fire extinguishers cannot be used to put out electrical fires, due to the presence of ________________________

    Right Option : C
    View Explanation

    Students / Parents Reviews [10]