When Should You Use a CO2 Fire Extinguisher?

Fires come in a number of different types, and depending on what is burning, you need to use the right kind of extinguisher to put them out safely. Some extinguishers are more effective for certain fires, while others can be dangerous when used at the wrong time, such as using a water based extinguisher on an electrical or kitchen fire.

One common fire extinguisher you’re likely to come across in many work environments directs carbon dioxide, or CO2, onto the source of a fire. In this guide, the team at Hoyles Fire & Safety explains how to identify a CO2 extinguisher, what a CO2 extinguisher can be used on, and when it should not be used.

How to Identify a CO2 Extinguisher

A CO2 extinguisher is one of the easiest extinguisher types to identify.

• It will have a black label across its body with CO2 in large white letters on it.
• At the end of the nozzle, you will find a large black frost free horn, unlike anything you’ll usually find on other extinguisher types. Because the extinguisher releases very cold gas, the horn helps reduce the risk of ice burns during use.
• There should also be a CO2 fire extinguisher sign fixed close by.

How does a CO2 fire extinguisher work?

A CO2 fire extinguisher works by releasing carbon dioxide gas at high pressure. When discharged, the CO2 displaces oxygen around the fire, helping to smother the flames and stop the combustion process. This is the main CO2 fire extinguisher function, and it makes this type of extinguisher particularly useful for electrical fires and flammable liquid risks.

Because carbon dioxide is a clean gas and does not leave residue behind, it is often used in offices, server rooms, plant areas and environments where electrical equipment needs protection. However, correct CO2 fire extinguisher use is essential. CO2 should only be used where suitable, and users should avoid discharging it in confined spaces due to the risk of oxygen displacement.

For businesses reviewing their extinguisher provision, Hoyles Fire & Safety can advise on the correct use of carbon dioxide fire extinguisher equipment and provide tailored fire extinguisher solutions across commercial premises.

What Can a CO2 Extinguisher Be Used On?

A CO2 extinguisher contains carbon dioxide in liquid form, which converts into gas when discharged. The gas helps smother the source of the fire by displacing oxygen, which is needed for combustion. In theory, this may make it sound suitable for many fire types.

In practice, there are several fires that a CO2 extinguisher should not be used on, which we’ll cover shortly. First, let’s look at what a CO2 extinguisher can be used on safely and effectively:

• Electrical fires – a CO2 fire extinguisher is often one of the preferred options for this kind of fire, which makes it a common sight in offices, server rooms and computer rooms. Because of its smothering effect, it can help prevent an electrical fire from reigniting, provided the power has been turned off at the source. As the gas quickly dissipates after discharge and leaves no residue, it should not damage electrical equipment in the same way as water, foam or powder.
• Class B flammable liquid fires – a CO2 fire extinguisher can also be used on certain flammable liquid fires, including those involving petrol, oil, diesel, paint and solvents.

When Is CO2 Fire Extinguisher Use Not Suitable?

Because a CO2 fire extinguisher smothers a fire with gas that then dissipates without leaving residue, it can sound like the perfect extinguisher. However, there are scenarios where CO2 fire extinguisher use is not suitable. These include:

• Class A solid fires – although CO2 is very cold when discharged, it quickly disperses. Materials such as wood, paper and plastics may continue to smoulder once the gas has cleared, meaning there is a risk of reignition.
• Class F cooking fat and oil fires – although a CO2 fire extinguisher can be suitable for some flammable liquid fires, it is not suitable for cooking oil or fat fires. Because the gas discharges at high velocity, it may spread the burning oil before it has the chance to smother the flames. Class F fires should instead be tackled with a wet chemical extinguisher.

One further note about CO2 fire extinguisher use: care should be taken when discharging them because of the potential for ice burns. You should also avoid discharging CO2 extinguishers in enclosed areas, as they displace oxygen in the air and could pose a risk of asphyxiation.

Here at Hoyles Fire & Safety, we supply, install and maintain all kinds of fire extinguishers, including CO2 fire extinguishers. If you’re not sure what type of extinguisher should be placed where at your premises, our experienced team can provide practical advice to make sure you, your staff and your business premises have appropriate protection.

Call us now to find out more.