Classes of Fire and Fire Extinguisher Ratings

If you are unfamiliar with the fire safety world, a glance at the side of a fire extinguisher will probably confuse you further!  In this short article, we’ll give a basic breakdown of fire classes and the ratings that accompany each extinguisher, to help you understand what the markings on a fire extinguisher mean and which fire extinguishers are best suited for the different types of fire.

Fire Extinguishers don’t have a one size fits all for every single fire and not all extinguishers are suitable for every type of fire.  That’s why, there are different classes.  The ratings that accompany them, give an indication of how effective a particular extinguisher is on a particular type of fire.

The main Classes of fire are:

A) Flammable Materials such as wood, paper, textiles.
B) Flammable Liquids such as petrol, oil, paraffin, alcohol and some paints.
C) Flammable Gases such as butane, propane and some natural gases.
D) Flammable Metals such as magnesium, potassium and lithium.
E) Fires involving live electrical equipment. Marked with a Lightning Symbol.	​​
F) Flammable cooking oils & fats found in kitchens.

Fire ratings are given to extinguishers to measure how effective they are for the classes of fire they are suitable.   Simply put; the higher the number, the more capable the extinguisher. Here’s some examples of the main types of extinguishers we sell and how we interpret their fire class &  rating.

2KG ABC Powder

13A 70B C

A popular all rounder best suited to outdoor or vehicle use, it has a good rating for Class A, an excellent rating for Class B and is suitable for Class C Fires. It is also safe for live electrical fires. This is an excellent all round extinguisher.

6L Water Spray

21A

The 6L Water spray is only suitable for Class A Fires.  It is not recommended for use on live electrical fires. The water spray does offer protection against inadvertent use on electrical fires up to 1000v. This is because the water is delivered in a spray, separating the water particles  and thus preventing a shock travelling to the user. Unlike Powder, it will not make a mess and so would be the go to option for any Class A Fire.

2KG CO2

34B

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The 2KG CO2 has no A Rating but has a 34B Rating for Flammable Liquids and is suitable for live electrical fires. You will commonly find CO2 Extinguishers in office environments, paired with 6L Foam or 6L Waters. CO2 is clean and a very effective fire fighting medium.  It is less effective outdoors.

6L Foam Spray (AFFF)

21A 144B

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Unlike the 6L Water, the Foam offers the added benefit of Class B protection with a high rating against Flammable Liquid fires but also carries the A Rating for fires involving Class A materials.  It is not suitable for live electrical fires, but like it’s water counterpart, benefits from protection against electric shock, if used inadvertently on live electrical equipment.

6L Multi/Wet Chemical

34A 233B 75F

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A more specialist extinguisher that gives excellent A and B ratings but crucially offers a 75F rating for use on fires involving cooking fats and oils. You’ll often find these extinguishers placed in commercial environments where cooking with these oils makes an F rated extinguisher essential.

This is only intended as a brief guide to the classes and ratings of extinguisher. If you’re in any doubt about what the best suited extinguisher is for your needs, get in touch on live chat or email sales@firesafewestmidlands.co.uk and we will happily advise.