Types of Fire Extinguisher
A fire extinguisher is a fire protection device that is used to extinguish or control fire often in emergency situations. There are different types of fire extinguishers available in the market but choosing the right kind of fire extinguisher is based upon the types of fires the extinguisher will be expected to put off. These fire extinguishers are rated for certain types of fires and this rating helps to determine where in the home, office, or car it will be best utilized. There are four types of fires:
- Fire due to any "ordinary combustibles"
- Fire due to flammable liquids such as gasoline etc.
- Electrical fires.
- Fire due to burning of reactive materials such as sodium, magnesium.
There are commonly six types of fire extinguishers that are available and each one is based on the above mentioned types of fires. The most common type of fire extinguisher is of Type A which is a Pressurized Water Extinguisher. Water has a great effect on cooling the fuel surfaces and thereby reducing the pyrolysis rate of the fuel. Most of the water based extinguishers also conatin traces of other chemicals to prevent the extinguisher rusting. This type of fire extinguisher is not suitable for for type C fires because of the risk of electrical shock. It may or may not extinguish class B fires as it depends upon whether the liquid molecules are poar or non-polar. If it is polar then its ok otherwise the water will merely spread the flames around. Type A extinguishers are normally silver.
Another type of fire extinguisher that is generally used is a carbon dioxide extinguisher. This high pressure fire extinguisher removes oxygen and works by suffocating the fire. This type of fire extinguisher can also be used on electrical wires as being a gas it does not leave any residues which might further damage the equipments. It is not suitable for type D fires because carbon dioxide will support the combustion of type D materials. Due to the extreme cold of the carbon dioxide that is expelled from an extinguisher, it should not be touched. CO2 extinguishers are normally red and have large nozzles. Similarly there is another type of fire extinguisher known as the Halon fire extinguisher containing a gas much heavier than carbon dioxide. This fire extinguisher is widely used in vehicles and computer suites. But they are not generally used as they are very expensive and secondly thye conatin choloroflourocarbons that cause damage to the ozone layer.
For types B and C, dry powder is used and are known as Dry Chemical Extinguishers. These powders act as extinguishing agents and they cool the chemical reactions to continue. The powders that are used in this type of fire extinguisher are often used in conjunction with foam for attacking large class B fires. They can be used on electrical fires but provide a significant cleanup. They should not be used for type A or D fires. Dry-chemical extinguishers are normally red, with small nozzles. The different types of fire extinguishers should also be maintained properly and there have to be regular checks for it that should be done to keep them in proper working conditions.