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A close-up of a fire extinguisher gauge

CO₂ Fire Extinguishers 

What types of fire should a CO₂ fire extinguisher be used on?

  • CO2 fire extinguishers can be used on Class B fires involving flammable liquids such as petrol or solvents. 

  • CO2 fire extinguishers are also widely used on electrical fires. The Carbon Dioxide in these extinguishers does not leave any residue, which is highly beneficial in environments with sensitive equipment.

When not to use a CO₂ fire extinguisher

​Class A fires

CO₂ fire extinguishers are not recommended for us on Class A fires as the
CO₂ does not act as a cooling agent, meaning the risk of reignition remains
after the initial fire is extinguished.

Class F Fires

For similar reasons, these extinguishers are not recommended on Class F fires involving cooking oils or fats.

Enclosed areas

In addition to this, CO₂ fire extinguishers are not suitable for use in small and enclosed areas, due to the potential for asphyxiation.

A collection of water, powder and CO2 fire extinguishers

How to recognise a CO₂fire extinguisher

CO₂ fire extinguishers are red in colour with a black coloured label reading ‘CO₂’ along with instructions for use. These extinguishers are also notable for their hard black cone, from which the carbon dioxide gas is expelled.


In addition to this, you should find an identification sign above the extinguisher with the categories of fire that it can/can’t be used on.

What are the common CO₂ fire extinguisher sizes available?

CO₂ fire extinguishers typically are available in 2KG and 5KG sizes. The pressurised gas makes the 5KG size heavier to manoeuvre, so this is worth keeping in mind.

How do CO₂ fire extinguishers work?

CO₂ extinguishers use carbon dioxide gas to replace the oxygen that fuels the fire, which has the effect of smothering the fire.

Which environments require CO₂ fire extinguishers?

CO₂ extinguishers are suited to environments where there is an electric fire risk, as well as environments which house sensitive equipment. Server rooms, industrial premises and artistic studios.

How to use a CO₂ fire extinguisher:

  1. Following identification of the type of fire as Class B or electrical - and not in an enclosed area - ensure it is safe to approach the fire without risking your safety. If the fire is electrical, ensure the power is turned off.

  2. At a safe distance away, remove the metal safety pin to break the plastic tamper seal.

  3. Aim the horn at the base of the fire, not at the flames themselves. Be aware that the horn becomes extremely cold during use, avoid touching it so as to avoid frostbite.

  4. Squeeze the handle to propel the CO₂ towards the source of the flames.

  5. Use a sweeping motion to move the jet of CO₂ from side to side until the fire is extinguished. 

  6. Once the fire is extinguished and remains that way, you should ventilate the area and call your fire protection company to service the extinguisher.


To learn more about fire and how to use fire extinguishers, there is online learning available here

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