Fire Extinguisher Ratings
& Fire Classifications

How To purchase Fire Extinguishers (UK Only)

If you are interested in purchasing fire extinguishers or any other type of fire safety equipment, I can recommend Screwfix, who offer a wide range of equipment at very competitive prices, with next day delivery.

They have over thirty years experience and are one of the largest and most reliable suppliers in the UK. You can view their workplace safety equipment page here.

See Also The Following Pages:

Main Fire Extinguishers Page

Water Fire Extinguishers

Carbon Dioxide Fire Extinguishers

Wet Chemical Fire Extinguishers

Dry Powder Fire Extinguishers

Halon Fire Extinguishers

How To Use A Fire Extinguisher

The History Of The Fire Extinguisher

Fire Extinguisher Ratings:
Understanding Fire Extinguisher Ratings

Fire extinguisher ratings are expressed as a combination of letters and numbers. The letter refers to the classes of fire that it can be used to extinguish, and the number refers to the size of fire than it is capable of dealing with. There may be several letters if the fire extinguisher is safe to use on more than one class of fire, and generally speaking, the larger the number the bigger the fire the extinguisher can put out.

The numbers are arrived at through testing the extinguisher against a fixed measure of effectiveness. For example, a fire extinguisher with rating 13A means that in a wooden crib test that appliance managed to successfully extinguish 1.3m of the fire. So the number is a measure under strict standardised test conditions of how big a fire the extinguisher can deal with.

With Class B fires (flammable liquids) the rating refers to the approximate area of fire in square feet that it can extinguish. Different tests are used with different fire types, but the principle is the same. The letter or letters denote the type of fires and the number the effectiveness of the extinguisher.

The number will often relate to the size of the extinguisher, but this is not the only factor. In water fire extinguishers for example an additive in the water can significantly increase the effectiveness of the extinguisher, so even though two extinguishers may be the same size, one could have a higher number rating than the other.

Fire Classifications:
Differences Between US and UK Classes of Fire

The fire classifications in the UK are similar to those in the US, but there are some important differences that should be made clear. Also, when I refer to 'UK', as far as fire classifications go this can also be taken to mean the whole of Europe and Australasia.

The following main headings refer to UK classes of fire - US fire classifications will be shown in brackets:

Fire Classifications - Class A Fires (US: Class A Fires)

Fires involving organic solid materials such as paper, wood, textiles, etc.

Fire Classifications - Class B Fires (US: Class B Fires)

Fires involving flammable liquids or liquefiable solids such as petrol, kerosene, diesel, paints or oils.

Fire Classifications - Class C Fires (US: Class B Fires)

Fires involving flammable gases such as propane, butane and methane.

In the US flammable gases are included with liquids in fire class B.

Fire Classifications - Class D Fires (US: Class D Fires)

Fires involving combustible metals or combustible metal alloys, such as sodium, potassium and magnesium and titanium.

Fire Classifications - Electrical Fires (US: Class C)

Fires involving electrical equipment.

This is sometimes referred to as Class E in the UK, but there is no such official fire classification. The rationale being that electrical equipment is often the cause of a fire, rather than an actual fire type.

Fire Classifications - Class F Fires (US: Class K Fires)

Fires involving cooking fats and oils (deep fat fryers).

Fire Extinguisher Ratings:
Types of Fire Extinguisher and Their Fire Classifications

Main fire classifications relate to the UK, US ratings are shown in brackets.

Fire Extinguisher Ratings:
Water Fire Extinguishers (colour: Red)

Classes of fire: A
(US: class A)

Fire Extinguisher Ratings:
Carbon Dioxide Fire Extinguishers (colour: Black)

Classes of fire: Electrical fires and A, B, C
(US: classes A, B and C)

Fire Extinguisher Ratings:
Dry Powder Fire Extinguishers (Colour: Blue)

Classes of fire: A, B, C and electrical fires
(US: classes A, B & C)

If using on an electrical fire the electricity supply should always be disconnected first.

Fire Extinguisher Ratings:
Wet Chemical Fire Extinguishers (Colour: Yellow)

Classes of fire: A, F
(US: classes A & K)

Fire Extinguisher Ratings:
Foam Fire Extinguishers (Colour: Cream)

Classes of fire: A and B
(US: classes A & B)

Fire Extinguisher Ratings - Pictograms

As well as colour coding and being rated with a letter and number, fire extinguishers also have a pictogram to show the classes of fires that it is safe to use on. The pictograms used are shown below:

Understanding fire extinguisher ratings and fire classifications is very important because using the wrong type of fire extinguisher on certain fires not only risks making the situation worse, but could be extremely dangerous.

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