Fire Extinguishers

Fire extinguisher types: How to choose the right class

Journalist, Cherry Park

Author Bio ▼

Cherry Park is an experienced freelance journalist and reporter who specializes in features, news, and news analysis, in print and online. She has written extensively in the areas of health and safety, fire safety, employment, HR, recruitment, rewards, pay and benefits, market research, environment, and metallurgy, and she also conducts research.
April 26, 2017

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Choosing fire extinguisher types for the relevant class of fire could literally be the difference between life and death.

No single extinguisher can be used to tackle every fire, and because each type of fire extinguisher has different classes of fire on which it is effective, selection can be a minefield.

The first step is to look at what materials are present in the area to be protected from fire. These can be divided into six categories of fire involving different substances:

  • Class A, combustible carbon-based solids eg paper, wood or textiles
  • Class B, flammable liquids eg paraffin, petrol, diesel or oil (but not cooking oil)
  • Class C, flammable gases, eg butane, propane or methane
  • Class D, burning metals, eg aluminium, lithium or magnesium
  • Fires caused by electrical equipment (indicated by an electric spark symbol and not the letter E)
  • Class F, fats and cooking oils.

In the UK, portable fire extinguishers must conform to BS EN3 Standard, which specifies that their body is coloured red. A small coloured band indicates the type of fire extinguisher – red for water, white and red for water mist, cream for foam, blue for dry powder, yellow for wet chemical, green for clean agent and black for CO2 extinguishers.

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The prices of all extinguishers vary widely according to supplier, so purchasers are advised to shop around. The future cost of servicing will also need to be taken into consideration. Some firms charge for installation and commissioning, but they should be supplied with a 5-year warranty and mounting brackets included. Approximate prices given below include VAT.

Five main types of fire extinguishers

  • Water, water mist or water spray
  • Foam
  • Dry Powder – standard or specialist
  • Carbon Dioxide (‘CO2’)
  • Wet Chemical

Fire extinguisher types chart

This chart visualises the fire extinguisher types and the types of fire for which they are suitable. Credit to Margarita Emmanuelli on Pinterest for this chart.

Fire extinguisher types chart

Fire extinguisher types and uses

Water fire extinguishers

Water extinguishers are only suitable for Class A fires consisting of paper, wood, straw, coal, rubber, solid plastics and soft furnishings. They are the simplest, most common, and least expensive type of extinguisher, costing from around £25 for 3- or 6-litre, to £35 for 9-litre ordinary models, and £50 for freeze-protected extinguishers. Some have an additive to make the water more effective and reduce the required size and weight of the extinguisher – these are a little more expensive.

Water extinguishers are the easiest to maintain variety and the least hazardous, since they only contain water. They cool the fire by soaking it and the materials with water. This extinguishes the flames, absorbing heat from burning objects.

They are often found in shops, offices, retail premises, schools, hotels, warehouses and domestic premises. They may have spray or jet nozzles and are usually able to put out a fire completely. A drawback is that they cannot be used on burning fat or oil (Class F), burning metals (Class D), burning liquids (Class B) or electrical appliance fires.

Water mist extinguishers

The newest type of extinguisher. These very powerful, but smaller, devices exude an ultra-fine mist of microscopic ‘dry’ demineralised water particles. They are safe and effective to use on Class A, B, C and F fires, making it unnecessary to supply more than one type of extinguisher in most premises. Some are also suitable for use on electrical fires on equipment up to 1,000 Volts, such as computers and printers.

They work by cooling the fire and reducing the oxygen supply. These devices are likely to replace wet chemical extinguishers for the extinction of deep fat fryer fires, and leave no residue or collateral damage. Like water extinguishers, they are recyclable and do not contain any chemicals. However, they cannot be used on Class D fires (metals).

Water mist extinguishers are more expensive than water extinguishers, costing from around £50 for 1 litre to £100 for 6 litres.

Water spray fire extinguishers

Available in three and six litres water spray fire extinguishers are suitable to fires involving organic solid materials such as wood, cloth, paper, plastics or coal. Use on burning fat or oil or on electrical appliances is a big no-no.

Use involves pointing the jet at the base of the flames and moving it constantly and steadily across the fire until extinguished.

A jet nozzle is eschewed in favour of a spray nozzle, which creates a fine spray courtesy of the higher pressure. Hitting a broader surface area this extracts heat more rapidly. Surfactants can be added to help the water penetrate further into burning material.

Foam extinguishers

The foam smothers the fire in solids and liquids (Class A and B), but not in burning fats or cooking oils (Class F). They can be used on some electrical fires if they have been tested and if fired from 1 metre away. However, they leave a residue that has to be cleaned up, and they are more expensive than water extinguishers, at around £25 for 1 litre and £55 for 9 litres.

Dry powder extinguishers

These are suitable for fighting burning solids, liquids and gases (Class A, B and C fires). Specialist powder extinguishers are designed to tackle type D fires involving combustible metals such as lithium, magnesium, or aluminium.

They work by the powder forming a crust which smothers the fire and stops it from spreading.

Disadvantages are that the powder does not soak into materials and does not have an effective cooling effect on the fire, which can result in the fire reigniting. The powder is hazardous if inhaled, so they should be used in well-ventilated areas and are not suitable for offices and domestic premises. The powder damages soft furnishings, machinery, etc, and needs a lot of cleaning up after use. They cannot be used on chip pan fires (Class F).

They are generally inexpensive and powerful and come in 1, 2, 4, 6 and 9-kg sizes. A 1kg model can cost as little as £15, while 9kg will cost around £35.

CO2 extinguishers

These contain only pressurised carbon dioxide gas and therefore leave no residue. They are suitable for use on fires involving burning liquids (Class B), and electrical fires, such as of large computer equipment, so are practical in offices. CO2 works by suffocating the fire and does not cause damage to the electrical items or cause the system to short circuit.

However, CO2 extinguishers get very cold during discharge, and those that are not fitted with double-lined, frost-free swivel horns may cause fingers to freeze to the horn during deployment. They can asphyxiate in confined spaces, and they are not suitable for deep fat fryers, as the strong jet from the extinguisher can carry the burning fat out of the fryer. Fires can quickly re-ignite once the CO2 has dissipated into the atmosphere, so they do not offer post-fire security.

CO2 extinguishers are quite expensive. A 2kg model costs around £33, while a 5kg model, suitable for server rooms and factories, costs from £65.

Wet chemical extinguishers

These are the only extinguishers apart from water mist suitable for Class F fires (fats and cooking oils) and are mainly used in kitchens with deep fat fryers. They can also be used on Class A and some can be used on Class B fires. They consist of a pressurised solution of alkali salts in water, which, when operated, creates a fine mist, cooling the flames and preventing splashing. More expensive than some others, they cost around £35 for 2-litre, £70 for 3-litre and £110 for 6-litre sizes.

Which fire extinguisher types to use

  • Class A fires – water, water mist, foam, dry powder, wet chemical
  • Class B – water mist, foam, dry powder, CO2, some wet chemical
  • Class C – water mist, dry powder
  • Class D – specialist dry powder
  • Electrical – water mist, foam, CO2
  • Class F – water mist, wet chemical.

Fire extinguisher use

Fire extinguishers should ideally only be used by someone who has been trained to do so – and the following text does not count as training. Moreover, a fire extinguisher should only be activated once the fire alarm has been triggered and you have identified a safe evacuation route. Evacuate the building immediately if you still feel unsure about using a fire extinguisher or if doing so is clearly the safest option.

Nevertheless, the following technique can serve as a refresher for those who have undertaken training or if someone without training ever needs to use one in order to improve the chances that everyone escapes unharmed.

The following four-step technique can be memorized more easily with the acronym PASS:

  1. Pull: Pull the pin to break the tamper seal.
  2. Aim: Aim low, pointing the nozzle or hose at the base of the fire. (Do not touch the horn on a CO2 extinguisher since it becomes very cold and can damage skin.
  3. Squeeze: Squeeze the handle to release the extinguishing agent.
  4. Sweep: Sweep from side to side at the base of the fire – the fuel source – until the fire is extinguished.

Read more on how to use a fire extinguisher safely and effectively.

Fire blankets, hoses and buckets

These methods of fire extinction are useful additions to extinguishers.

Fire buckets can be used filled with water on Class A fires, or with sand to use as an absorbing agent on spilled flammable liquids (Class B). They must not be used with water on burning fat or oil or on electrical appliances. However, they’re sometimes left empty or misused and have a limited effect as they can’t used on large fires. Plastic fire buckets with lids cost around £15, while metal ones can be bought for around £23.

Fire hoses let out water at high pressure. They can be effective on Class A fires, but are very heavy. Prices of hose reels start at around £100 and vary widely depending on size and mounting.

Fire blankets are effective in smothering small, contained fires in kitchens or boats, if a good seal is made, and for wrapping round people whose clothing is on fire. Made of fibreglass, they can withstand temperatures of up to 500° C and are compact and portable. They don’t need any maintenance but can only be used once. They are cheap, and can be purchased for as little as £7 for a one-metre square blanket. Larger sizes cost around £15.

Automatic fire extinguishers

Automatic fire extinguishers are designed to combat fires in transport, such as in the engine compartments of boats or large vehicles, or in industrial use, such as in generator or computer rooms. Advantages include easy recharging and lack of constant monitoring, and removal of the need for manual operation in unmanned areas.

These extinguishers are designed to spring into action when they detect heat. On the downside, their placing is crucial, since they could be set off erroneously when the ambient temperature reaches the trigger level.

Available as dry powder (blue) or clean, inert extinguishing gas, which replaces the now illegal halon, banned in the UK because of its effect on the ozone layer (green), they protect against Class A, B, C and electrical fires.

They cost from £30 to £85 for smaller models; complete systems can cost from £500 to £1,750.

Vehicle fire extinguishers

Generally containing dry powder for tackling Class A, B and C fires, their size should be selected according to the size and type of vehicle. They can be bought for around £11 for a 600g model to £70 for 12kg for larger vehicles. Their use is advisable, but is not a legal requirement in ordinary cars.

Fire extinguisher covers

Cost between £8-£25 depending on size and are used to protect extinguishers in harsh environments. Hose reel covers are also available.

Further reading: Fire extinguishers: your legal obligations

Read more fire safety news, features and guides.

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Bernard Clyde
Bernard Clyde
May 16, 2017 4:25 pm

I appreciate you explaining the different classes of items as well as fire extinguishers, Cherry, and how both need to be considered before tackling a fire. It’s important people understand this so that they can adequately put a fire out before things get out of hand. Plus, I think it can instill a lot of confidence in individuals when a fire does happen which can help them to take action and fix the problem.

Violette Lebrac
Violette Lebrac
August 15, 2017 3:54 am

Cherry, I didn’t know that water extinguishers are the easiest to maintain and the most likely to be found around in schools and shops. I am looking to get a fire extinguisher to put in my home in case of kitchen fires, and I want to find the kind that would be the most effective. A water extinguisher might not put out oil fires in the kitchen, so I’ll probably consult a professional to help me decide.

Nishant sharma
Nishant sharma
November 17, 2019 7:44 pm

You have to used water -mist type fire extinguisher ,it is the best or if it is not available so u try DCP ( dry chemical powder type extinguisher ,it is also know as brahmastr because it extinguisher all type of fires.

Venkatesh Chekuri
Venkatesh Chekuri
February 7, 2020 8:51 am

class k (purple class) fire extinguisher is the only thing which is proffered for kitchen fires.

Fayez Ahmed
Fayez Ahmed
February 18, 2020 4:21 am

It ids better to have Dry Powder fire extinguisher at home

ajay keni
ajay keni
May 2, 2021 11:28 am

class k (purple class) fire extinguisher is the only thing which is proffered for kitchen fires.

Last edited 1 year ago by ajay keni
Alexandria Martinez
Alexandria Martinez
September 12, 2017 3:05 am

As my fiance and I looked into getting a fire extinguisher for our home, I was shocked to find out there are different kinds of extinguishers. We will be keeping it in our kitchen. This means we’ll need one that can put out grease fires. Thanks for the post! This was very helpful.

Adam Bannister
September 13, 2017 5:27 pm

Glad we could be of help!

extintores secom
extintores secom
October 2, 2017 7:03 pm

is there any difference between F and K class? De pends of the country or region?

Hilary Birungi
Hilary Birungi
January 15, 2019 3:04 pm

what is the best recomended fire extinguisher to be used in a super market?

May 11, 2019 1:24 am
Reply to  Hilary Birungi

Maybe a few months old, but posting nonetheless 🙂 Fire Tech for last 11 years. In this situation there is no ‘Best’ type to use as such. The exact area and types of devices or products need to be considered. If it is in the food prep area for example and it is to cover the small switch board, then you would use an CO2 3.5kg in size. NOT a powder of any type or water. Keep in mind, the powder inside of ‘dry powder extinguishers’ is very similar in behavior to talcum powder. Meaning, it goes everywhere!! And it… Read more »

Eli Richardson
Eli Richardson
October 1, 2019 8:42 pm

Thanks for providing a diagram of the different extinguishers and where to use them. My uncle recently opened a restaurant and needs to buy some fire extinguishers. I’ll recommend him the Class F and C for his commercial kitchen.

Last edited 1 year ago by James Moore
Eileen Benson
Eileen Benson
January 8, 2020 6:11 pm

It was helpful when you said that CO2 extinguishers are a good option for office buildings because they’re capable of handling electrical fires without leaving any residue. My brother needs to figure out the fire suppression system for the new office building his company will be moving to later this year. The info you share here should help him as he starts talking with a fire suppression equipment provider.

Jenna Hunter
Jenna Hunter
February 5, 2020 10:29 pm

I can see how it could be really useful for a business to make sure that they have the right fire extinguisher to help prevent fires. It could be really nice for them to get a recharging station for them so that it is more helpful. It was interesting to learn about how water mist can help get rid of fire that is from wood, textiles, liquids, gases, and cooking oils.

Last edited 1 year ago by James Moore
Shaylee Packer
Shaylee Packer
February 20, 2020 1:16 pm

You mentioned that the most common fire extinguisher is the water fire extinguisher. It seems like there are a lot of things that this one does not put out. In order to be covered on all fronts, is it best to have multiple different kinds on hand?


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