A Guide to Fire Extinguishers

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We get asked all the time – what types are available, and what do I use them on?

First of all, lets look at the how different fires are broken down into different classifications.

Class A Combustible materials such as wood, paper and textiles
Class B Flammable liquids such as petrol and paint
Class C Flammable gases such as methane and propane
Class D Combustible metals such as Lithium, Potassium and Magnesium
Class F Cooking oils and fats

 

Electrical fires no longer have a class, but are a consideration.

There are specific extinguishers available to tackle the fire types above, and here we are going to go through them so that you can educate yourself on the correct one for your property.

What fire extinguishers are available?

  • Water
  • Foam
  • Carbon Dioxide (CO2)
  • Wet Chemical
  • Dry Water Mist
  • Dry Powder

Before we start, it is important that we point out that you should never use a fire extinguisher on a burning fire unless you are confident you are able, and that it is safe for you to do so. If you are in any doubt, please leave the building and call 999 for the fire service.

What type of fire do I use a water extinguisher on?

Although water is probably your first thought when putting out any fire, this type of extinguisher should only actually be used for a Class A fires. This is when you are tackling a fire where the fuel is a combustible material such as paper or woods, and using a water extinguisher is a good option as it drenches the material and eliminates the fuel at the same time.

You should avoid using these types where an electrical fire has started as water does not mix well with electricity and you may put yourself at risk of getting electrocuted. You should also not use this type for flammable gas and liquids.

What type of fire do I use a foam extinguisher on?

A foam extinguisher can be used on a Class A fire too, but they can also be used on flammable liquids, such as petrol – these are known as Class B fires.

This type of extinguisher sprays out an expanding layer of foam, that cools down the burning material and creates a barrier to stop oxygen fuelling the fire.

What type of fire do I use a Carbon Dioxide (CO2) extinguisher on?

This type of extinguisher can also be used on Class B fires and is one of the best fire extinguishers for electrical fires (for example this is the type you would find in a server room). The extinguisher contains pressurised CO2 gas, so when spraying the strong jet of CO2 on a fire, you are depriving the burning fire of any oxygen. It is important to remember that once you have eliminated any fire, check that there are no burning embers as once the CO2 has dissipated and O2 comes back, it could provide enough oxygen for the fire to start up again.

What type of fire do I use a wet chemical extinguisher on? 

These are specifically designed for use on fires caused by cooking fats and oils, for example chip pan fires, which are Class F fires. Using any other type of extinguisher on a Class F fire can have the opposite effect and make it worse.

Wet chemical extinguishers have a specially adapted hose comes with a lance which sprays out a layer of foam on the burning material. create a layer of foam on the surface of the burning oil or fat, preventing oxygen from fuelling the fire any further.

What type of fire do I use a dry water mist extinguisher on?

The unique nature of these water mist extinguishers mean that they can be used safely and effectively on a wide range of fires that include Class A, Class B, Class C and electrical.

Dry mist extinguishers are the first that can tackle general fires as well as deep fat fryer fires which are very difficult to extinguish and currently require specialist wet chemical fire extinguishers to tackle them.

In Summary

If you are in any doubt over the type of extinguisher you need for your business, please get in touch with our team for a chat. There is no obligation to buy from us – your safety is our priority over any sales.

Author

Scott Taylor MIFireE, MIFSM, CFPA E-Dip TC

Scott Taylor has worked as a fire professional for over 15 years working in the public and commercial sector. He likes to work with businesses as a partner, passing on knowledge and information in a pragmatic manner balancing risk, benefit and cost to ensure compliance.

All stories by: Scott Taylor MIFireE, MIFSM, CFPA E-Dip TC