CO2 fire extinguishers

CO2 extinguishers are the extinguisher of choice for electrical fires. Although they also work on flammable liquid (class B) fires. We explain all in our simple guide.

CO2 fire extinguishers are primarily used for electrical fires and often paired with foam extinguishers.

Read about more fire extinguisher types: foam fire extinguishers, dry powder fire extinguishers, water fire extinguishers, wet chemical fire extinguishers.

Also known as:

Carbon dioxide fire extinguishers

Carbon dioxide extinguishers

CO2 fire extinguisher uses:

• Fires involving equipment such as computers, or generators (‘electrical’ fires)
• Fires involving some flammable liquids, such as petrol, diesel, and paint (‘class B’ fires)

Do not use CO2 extinguishers for:

• Cooking fires involving oil and grease, such as chip pan fires (‘class F’ fires)

CO2 fire extinguishers

How to identify a CO2 extinguisher:

• BLACK coloured label stating ‘CO2’
• The nozzle ends in a distinctive black ‘horn’
• Should be identified by an extinguisher ID sign fixed nearby – ‘CO2 Extinguisher’

Sizes of CO2 fire extinguisher available:

• 2 kg
• 5 kg (most commonly used)

How CO2 fire extinguishers work:

CO2 fire extinguishers discharge CO2 gas, also known as carbon dioxide.  This is stored in the extinguisher as a liquid, and the gas is created under pressure when the handle of the extinguisher is squeezed.

This causes the CO2 gas to emerge at great speed, which is why CO2 fire extinguishers are not recommended for chip pan fires – they could literally blast the flames into surrounding areas.

Unlike water and foam extinguishers, CO2 fire extinguishers do not work by cooling the fire and so are ineffective on fires involving flammable solids.

Instead, CO2 extinguisher work by replacing the oxygen surrounding the flames with carbon dioxide, meaning the fire can no longer burn.

Pros and Cons of CO2 extinguishers:

Pros: extremely effective on electrical fires; do not leave any residue behind when they are used.

Cons: risk of cold burns if the user holds the extinguisher by the horn; less environmentally friendly than other types of extinguisher; they replace the oxygen in the air with CO2 so risk of asphyxiation if used in confined spaces. See the following link for a full article explaining the correct use of fire extinguishers in confined spaces.

Who needs CO2 extinguishers?:

CO2 fire extinguishers should be standard issue for premises with live electrical fire risk, such as: • Offices
• Shops
• Schools
• Hospitals

CO2 fire extinguishers are particularly suitable for offices where there is a lot of electrical office equipment.  Pairs of CO2 and Foam extinguishers are often recommended for this kind of internal environment, as this covers the vast majority of fire risks likely to be found.

More about the different variations of extinguisher.

Learn what the different fire extinguisher colours mean.

How to use a CO2 fire extinguisher:

CO2 fire extinguishers how to remove safety pin
Removing a safety pin

Use CO2 extinguishers carefully, avoiding holding the extinguisher by the horn.

Remember – don’t use CO2 extinguishers in a confined space.

In all cases, firstly remove the safety pin to break the anti-tamper seal, and stand well back from the fire. Avoid holding the extinguisher by the horn.

Using the extinguisher:

• Aim the horn at the base of the fire and move the jet of CO2 backwards and forwards
Electrical fires: Switch off the electrical item if it is safe to do so
Liquid fires: Take care not to splash the burning liquid onto nearby areas


If you think you need CO2 fire extinguishers, or you’re not exactly sure what you need, please get in touch with our friendly team by calling 0800 157 1113, or emailing

They can arrange a free survey visit for you from a BAFE registered extinguisher engineer.

All of our carbon dioxide fire extinguishers come with a 5 year guarantee, and we’ll fit and commission them for you for free.