Fire Extinguisher Categories

Fire extinguishers come in different types, not all types are suitable for all categories of fires, and in fact most have only one or two applications.  Many people find that when trying to specify types of extinguisher they run into problems.  We often find that without some advice money is wasted on inappropriate fire extinguishers. To help overcome this we have created a short guidance that should help

Firstly let’s have a look at the types of fire.

Class A: Wood, Paper and Textiles

These are substances that will burn to a carbonaceous ash.  The class A risk is usually the first to be considered when installing extinguishers, as this type of risk is the most common.  These fuels might include waste paper, furnishings, and the fabric of a building, for instance doors, floorboards etc.

Class B: Flammable Fluids

Normally hydrocarbons, these include petrol, oil and many types of paints, thinners and solvents.

Class C: Gas

Fires caused by leaking gas, these should never be extinguished by anyone other than a trained fire-fighter.

Class D: Metals

Various metals will burn; these include magnesium, titanium, lithium and aluminium.  If you have these risks you should take advice from your local fire service.

Class E

There is actually no class E, when this is used it normally refers to fires with an electrical complication.  However electricity itself does not burn.

Class F: Cooking Fats and Oils

Essentially commercial deep fat fryers.

Range of Fire Extinguishers

Now we know what we are dealing with, we have a range of extinguishers that can deal with various types of fire.

Water

Water fie extinguishers are only type rated for class A fires and presents risks when used in the vicinity of electrical equipment or on burning oils.

AFFF (Aqueous Film Forming Foam)

AFFF foam fire extinguisher sare suitable for Class A fires and Class B fires.  It should however be noted that specialist foams are required to deal with alcohols such as ethanol.

CO2

CO2 fire extinguishers are suitable for use on Class B fires and fires with an electrical complication.  Its most typical application is for use on office machinery and IT equipment.  In most cases they are not appropriate as the principle extinguisher type in a building as they are unable to achieve an A class rating.

Powder

Powder fire extinguisher are suitable for use on Classes A B C and electrical fires.  It is a highly effective extinguishant but does present other problems.  It drastically reduces visibility, it can cause choking and respiratory distress in confined spaces.  It causes a great deal of mess and on exposure to atmospheric moisture can become corrosive.

Wet Chemical

This is a type of extinguisher designed specifically for use on deep fat fryers. They are also usually rated for class A and B fires.  An essential piece of equipment where deep fat fryers are used.

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