Unsplash Licence – Tak-Kei Wong

In the UK, fire extinguishers are painted signal red so they can be seen easily in an emergency. However, they also have a coloured box near the top. This colour corresponds to the class of fire that the extinguisher can fight, so it’s essential an individual uses the correct type. Here’s a simple guide explaining the fire extinguisher colours and uses so you can put out fires safely.

Why Are Fire Extinguishers Colour Coded?

The colours on fire extinguishers dictate which types of fire they can fight. This key is crucial, as using the wrong fire extinguisher can be ineffective and put the user at risk. 

Until 1997, the whole body of the fire extinguisher canister was colour-coded, so powder fire extinguishers had previously been entirely blue. However, this system changed. Now, most of the extinguisher is red with a small colour-coded section near the top. The extinguisher is now more obvious, as a red fire extinguisher is easily visible in an emergency, and the colour is synonymous with danger and fire. 

Fire Classifications

A fire is classified by the materials that are involved in it. There are six variations:

    • Class A – fires involving combustible materials, such as paper or timber
    • Class B – fires involving flammable liquids, like paint or petrol
    • Class C – fires involving flammable gases, such as propane or butane
    • Class D – fires involving flammable metals such as lithium or potassium
    • Electrical – fires involving electrical equipment
    • Class F – fires involving fats, like chip pan fires

The Different Fire Extinguisher Colours

There are five colours used on fire extinguishers that identify what they spray to fires:

    • Red – Water/ Mist
    • Cream – Foam
    • Blue – Powder/ABC
    • Black – Carbon Dioxide (CO2)
    • Yellow – Wet Chemical

Fire Extinguisher Types

There are five different types of extinguishers. Each uses a different method to fight fires, so extinguishers are available to put out every possible class. 

Clip art water fire extinguisher

Water/ Mist Extinguishers

Colour: Red

How They Work: These extinguishers spray water on a fire to cool it down and put out the flame.

What They Fight: Fires involving combustible materials like wood, cardboard, paper and coal.

Avoid Using Them On: Electrical fires, cooking oil fires, flammable liquids or gases.

Where They Are Used: Buildings with organic materials like offices, schools, hospitals, warehouses, barns.

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Foam Extinguishers

Colour: Cream

How They Work: By spraying foam on a fire, these extinguishers are able to separate the flames from the fuel, so they cannot sustain themselves.

What They Fight: Fires involving combustible materials and flammable liquids.

Avoid Using Them On: Flammable metals fires, electrical fires, cooking oil fires.

Where They Are Used: Buildings with organic materials like offices, schools, hospitals, warehouses.

 

Most buildings will need both water and foam extinguishers.

Clip art foam fire extinguisher

CC0 1.0 Universal (CC0 1.0) – Firkin

Clip art powder fire extinguisher

Powder Extinguishers

Colour: Blue

How They Work: Blue extinguishers spray powder onto a fire, suffocating it of the oxygen it needs to thrive.

What They Fight: Fires involving flammable liquids, gases and combustible materials. That’s why they are also known as ABC extinguishers.

Avoid Using Them On: Cooking oil fires, large electrical fires, fires in enclosed spaces.

Where They Are Used: Businesses using flammable gases, welding and flaming cutting locations, car garages and petrol stations, buildings with large boiler rooms.

CC0 1.0 Universal (CC0 1.0) – Firkin

Carbon Dioxide Extinguishers

Colour: Black

How They Work: These fire extinguishers release CO2 in a spray. In doing so, the oxygen that is sustaining the fire is replaced and suffocated.

What They Fight: Flammable liquid fires and electrical fires.

Avoid Using Them On: Cooking oil fires, organic material fires, flammable gases and metal fires.

Where They Are Used: Anywhere with large amounts of electrical equipment such as building sites, server rooms, office blocks, and commercial kitchens. Vehicles like coaches, buses and minibuses are legally required to carry at least one 2L CO2 extinguisher.

Clip Art CO2 Fire Extinguisher

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Clip art wet chemical fire extinguisher

Wet Chemical Extinguishers

Colour: Yellow

How They Work: Yellow extinguishers spray a thick, soapy foam of wet chemicals that covers a fire, removing its access to oxygen.

What They Fight: Organic material fires and cooking oil fires.

Avoid Using Them On: Fires involving flammable metals, liquids or gases fires, electrical fires.

Where They Are Used: Professional kitchens, restaurants, canteens.

CC0 1.0 Universal (CC0 1.0) – Firkin

Which Fire Extinguisher Colour Fights Each Classification

Table showing which extinguisher colour can fight each class of fire

Using the wrong fire extinguisher can have disastrous consequences. It can increase the size of the flames and help the fire spread. You can also cause chemical reactions that omit toxic gases or trigger explosions. The biggest risk is putting yourself and others in danger, especially if you use a water or foam extinguisher on an electrical fire. The electrical current can flow up the conductive water or foam and electrocute you. 

Water Spray Or Mist Extinguishers – What’s The Difference?

Both water spray and water mist extinguishers are characterised by their red colour code. However, they work in different ways, and water mist extinguishers are safer, more effective and more popular than their spray counterparts.

A water spray extinguisher shoots a jet of water to cool a fire. Alternatively, a water mist extinguisher sprays a mist that is too fine to conduct electricity at regular voltages. Therefore, they are safe to use on low-voltage electrical fires. Additionally, they don’t leave puddles that could conduct other currents, unlike a water spray extinguisher. 

Fire Extinguisher Life Span

You can take steps to increase the lifespan of your extinguishers and ensure they work effectively when you need them. Current UK guidelines advise that you replace most extinguishers every five years, although CO2 variations can last for ten. The British Standard for fire extinguishers (BS 5306-3) requires you to test and service them annually to guarantee they are functional if the worst happens. 

Our Fire Extinguisher Servicing

That’s where Cardinal Fire Protection comes in. Our BAFE registered technicians ensure that your extinguishers meet testing expectations. We work with clients in education, construction, retail, manufacturing, leisure and office environments to maintain the best fire safety standards.

Contact us today for more information about how we can help you stay safe.