Fire extinguishers are an active fire protection device used to help control small fires. Do not try to use them for fires that are already out of control. Nitrogen is used in most dry chemical fires, and water or foam types are pressurized with air.

A fire extinguisher will always list the types of fires it is designed for; for instance, chemical or electrical fires. Always read your fire extinguishers instructions to ensure that it’s the right type for the fire you’re dealing with. There are different classifications for types of fires and fire extinguisher in each country. These specifications however are largely the same across the board. The UK uses a five-category system. There are Class A fires (wood and/or paper), Class B (liquefied solids and/or flammable liquids), Class C (gases), Class D (metals) and Class F (cooking fires). UK fire extinguishers will be coded by letter and number; eg – 13A.

Fire Extinguishers are posted with the types of fires that it is made for, such as an electric fire or a chemical fire. Read the instructions on the fire extinguisher before using it to ensure that you are not going to use the wrong type. There is a sign on every fire extinguisher. Every country has its own specifications for certain classes of fires. In many countries these specification are the same and only have a few differences.

CO2 fire extinguishers are powder-based. These work by stopping the chemical reactions which allow the fuel to oxidize, suffocating the fire quickly.

For an electrical fire, the UK uses either CO2 or a powder, and there will be an electrical pictogram signifying that this fire extinguisher is for electrical purposes only. Some fire extinguishers use foam. There are different types of foam for different types of fires. Aqueous Film Forming Foam is used to suppress vapors on both Class A and Class B fires. Alcohol resistant Aqueous Film Forming Foam is used on chemical fires that contain alcohol. This type of foam forms a membrane between the fuel and the foam, which prevents the alcohol from breaking down the blanket of the foam. Film Forming Fluoroprotein is more heat resistant and is used more in the racing industry. Compressed Air Foam System fire extinguishers are charged with foam and pressurized with compressed air. They are used mainly for wooded areas, which are classed as A, or B. Arctic Fire is a liquid extinguisher that cools heated materials faster than the ordinary foam and is used on Class A, B, and D fires in the steel industry. The use of Co2 fire extinguishers is necessary for sensitive electronic and even important documents. The reason Co2 is used is that it does not leave any type of residue on the fragile parts of the electronics.

In forestry, Compressed Air Foam Systems are helpful in containing Class A and B fires in wooded areas. There are also Arctic Fire extinguishers. These quickly cool superheated materials and are used extensively in the steel industry to put out Class A-D fires. When there are electronics or documents to be protected, CO2 fire extinguishers are employed; these are suitable for use around these delicate materials since they do not leave residues behind.

A CO2 fire extinguisher uses powder to halt the chemical reaction which cause the fuel to oxidize; this cuts off the flames from the fuel to quickly extinguish fires. Grease and electrical fires call for specialized fire extinguishers. Water can present a hazard with grease or electrical fires (and in the case of electrical fires, can be fatal).

Everyone should be informed of the types of fire extinguishers that are being used around their work areas. If you do not know or are not sure, ask one of your supervisors to explain them to you.