Fire extinguishers have a key function at the start 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. According to current recommended practice, extinguishers should be placed a maximum of 30m apart, and you need one extinguisher for every 200m² of floor area.

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. A fire blanket should be fitted in kitchens, since not all fires can be put out with an extinguisher. 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.

Fire extinguishers are a very important safety item. You can use the red water extinguisher on Class A fires, i.e. fires that involve wood, paper and textiles. Foam extinguishers can be used as an alternative to the water type extinguisher. 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).

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

P – Pull the safety pin. Hold the extinguisher with the nozzle pointing away from you, and free the locking mechanism.
A – Aim the nozzle at the base of the fire, from a safe distance.
S – Squeeze the handle slowly and evenly.
S – Sweep the extinguisher from side to side while aiming at the base of the fire.

Fire Extinguisher Use and Safety Tips

• Use portable fire extinguishers when the fire is limited to a small area, such as a wastebasket, and is not growing; everyone has left the building, the fire brigade has been called, and the room is not filled with smoke.
  
• For a small office or workplace, you can choose multi-use fire extinguishers that are big enough to douse small fires, but not so heavy as to be hard to control.
  
• Select a fire extinguisher that bears the label of an independent testing laboratory.
  
• Read the instructions that come with the fire extinguisher and get the hang of its parts and operation before a fire breaks out.
  
• Mount fire extinguishers close to an exit and keep your back near the exit when you use the apparatus so you can make a quick escape if the fire cannot be controlled.
  
• Know when to go.

At regular intervals examine your fire extinguishers to verify if they need to be recharged or replaced. Check the manufacturer’s instructions for operating guidelines, including proper distance between the extinguisher and the fire.