You'd be forgiven for thinking that all fire extinguishers were born equal but this really isn't the case. Different fire extinguishers use different materials to extinguish fires and there are also different sizes. There are certain regulations that need to be met but otherwise it's a case of choosing the most appropriate type of fire extinguisher for its proposed use. Fire extinguishers for the home or car would typically be quite different to those required in industrial units or in laboratories for example.
* The most common and all round extinguishers are considered class A extinguishers and are most effective against solid combustible materials like wood, fabric, and rubber. The numerical component of the classification, for example the 2 in a 2-A extinguisher, is the size of fire in cubic metres that can be put out with that extinguisher.
* Class B are designed for liquid fires such as those involving petrol. The numeric component of the class offers guidance on how many litres of burning fluid the content of extinguisher can put out. For example, a 2-B fire extinguisher should be able to extinguish 2 litres of petrol or other flammable liquid.
* Class C are gas fire extinguishers. These do not offer a numerical value purely because it is virtually impossible to measure gas in cubic metres as it will depend on the ratio of gas to air in the local atmosphere.
* Class D are for extinguishing metal fires and the numerical value once again determines the size of fire that can be extinguished measured in cubic metres.
* Class E or Electrical are for electrical fires and there is no numerical value applied to the fire extinguisher for electrical fires.
Electrical fires are difficult to extinguish because once the source of the electric is shut down, if the fire continues then it will have changed class.
* Class F is specifically for cooking oil fires. These are more specific than class B but the numerical value represents the same volume of flammable liquid that can be extinguished with the contents.
In reality, some fires may start as one type but then progress to include others especially if they are not combated early and quickly. It can prove difficult to legislate for such fires, but you should take care to consider the combustible materials that are present as well as the likely causes of fire when choosing the most suitable type of fire extinguisher.