Fire extinguishers play a key role at the beginning of a fire. The different types of fire and the fire extinguishers used to fight them are broken down into four categories:

• Paper, wood, textiles and other easily ignited materials.
  
• Gases and fluids such as oil, solvents and lubricants.
  
• Electrical fires.
  
• Metals such as magnesium and sodium.

Fire as a general rule is caused by a chemical reaction between oxygen in the atmosphere and some sort of fuel. The sequence of events in a typical wood fire is as follows:

1. Wood is heated to a very high temperature.
   
2. The heat decomposes some of the cellulose material that makes up the wood when it reaches about 150 degrees Celsius.
   
3. Some of the decomposed material is released as volatile gases.

Fire extinguishers and hoses can be used to put out a small blaze, but their chief function is to help people make their way out of a burning building. Fire extinguishers in the workplace should be modern pieces of equipment that meet the terms of the BS EN 3 Standard. The first kind of cover that is required would be from extinguishers that contain water or foam.

Extinguishers should be placed a maximum of 30m apart, and you need one extinguisher for every 200m² of floor area, according to current recommended practice. Some fires can be made even worse with water or foam extinguishers, and it is common practice to put additional extinguishers of different types next to specific hazards like cookers and boilers.

Since not all fires can be put out with a fire extinguisher, a fire blanket should be fitted in kitchens. Extinguishers should be fixed to the wall with the supplied clips; where this is not possible, small plastic or metal stands are readily available to take the extinguisher with a sign. It is acceptable to use multipurpose extinguishers, such as the 2kg dry powder type, in smaller buildings.

Fire extinguishers are a very important safety item. They should be mounted in an easily accessible place. Make sure to check them monthly to ensure that they are properly stored, charged and undamaged. Check the gauge to make sure the extinguisher is still charged, and the seals to make sure they have not been tampered with. You should have rechargeable extinguishers recharged, and disposable ones replaced once you use them.

You can use the red water extinguisher on Class A fires, i.e. fires that involve wood, paper and textiles. Do not use this type of extinguisher on live electrical equipment, due to the risk of electrical shock. You should also avoid using it on flammable liquids, since water causes this type of fire to spread. You can use it in all areas of the building for general fire protection, with a minimum of two per floor.

Foam extinguishers can be used as an alternative to the water type extinguisher. These extinguishers are sometimes cream in colour, and are good for Class A and Class B (flammable liquids) fires. Foam should not be used on live electrical equipment. You can place them in all areas of the building, especially where flammable liquids may be present.

Blue powder type extinguishers can be used for Class A and Class B fires, and also for Class C (gas) and Class E (electric hazards). They can be placed in all locations, in addition to water or foam extinguishers, where Class C and Class E hazards exist. Note that not all powder extinguishers may be used on Class A fires. However, they provide good backup for other kinds of fire extinguishers.

Handling the Extinguisher

The classic steps for operating fire extinguishers (described by the acronym PASS) are the following:

P – Pull the safety pin
A – Aim the nozzle at the base of the fire, from a safe distance
S – Squeeze the handle
S – Sweep the extinguisher from side to side while aiming at the base of the fire.