Whether you’re fitting out an office, managing a workshop, or simply brushing up on workplace fire safety, knowing which extinguisher to use, and when, is vital. One of the most common types you’ll encounter is the CO2 fire extinguisher.
What is a CO2 Fire Extinguisher?
First and foremost, a CO2 (carbon dioxide) fire extinguisher is a type of extinguisher that uses compressed carbon dioxide gas to put out fires.
Technically, the gas is kept under such high pressure in the extinguisher that it turns to liquid. When you release the pressure, that is, when you use the extinguisher, the liquid turns to gas. This gas is dry and inert. When discharged, it starves the fire of oxygen and cools the flames at the same time – tackling two of the three elements a fire needs to survive (the three elements of the ‘fire pyramid’ being oxygen, heat and fuel).
CO2 extinguishers are instantly recognisable by their black label and frost-free discharge horn. They don’t leave a mess, which makes them ideal in places where cleanliness and equipment safety matter.
What Is a CO2 Fire Extinguisher Used For?
A CO2 fire extinguisher is recommended for:
- Electrical Fires: These are fires involving live electrical equipment such as computers, servers, and machinery. Because CO2 is non-conductive and leaves no residue, it’s safe to use on and around sensitive electronics.
- Class B Fires: These involve flammable liquids like petrol, paint, or solvents. While not the most ideal extinguisher for Class B fires, CO2 extinguishers are still suitable for putting them out. It’s very important you choose the right fire extinguisher for Class B fires, as the wrong one can likely result in the fire spreading.
When NOT to Use a CO2 Fire Extinguisher
CO2 extinguishers aren’t suitable for all types of fires. You should not use a CO2 extinguisher on:
- Class A Fires: These are fires that involve ordinary combustibles or things that burn easily such as wood, paper and fabric. CO2 won’t soak or penetrate these materials, so the fire can reignite easily.
- Class F Fires: These are fires involving cooking oil or fat. Using a CO2 extinguisher on a chip pan or deep-fat fryer can be dangerous, as it may cause hot oil to splash and spread the fire. We’d say a CO2 extinguisher is no good for a kitchen, and that you’re better off with a wet chemical fire extinguisher or fire blanket.
- Confined spaces: CO2 works by displacing oxygen, which can make it hazardous in small or poorly ventilated areas. Always take care when using it indoors.
Where Are CO2 Fire Extinguishers Most Suitable?
CO2 fire extinguishers are a common choice for premises with electrical equipment. Examples include:
- Offices: Especially where computers, printers and other electronic devices are in regular use.
- Server rooms and data centres: To protect delicate electronics without causing damage or downtime.
- Retail premises: To cover electrical fire risks in tills, displays, and back-office equipment.
Many businesses will pair a CO2 extinguisher with a foam or water extinguisher to cover both electrical and Class A fire risks. This ensures a more complete fire safety coverage.
Maintenance and Regulations
CO2 fire extinguishers, like all fire safety equipment, require regular maintenance to ensure they remain safe and effective. In the UK, the British Standard BS 5306-3 sets out the recommended maintenance protocols. You are advised to conduct your own monthly checks as outlined below, and to have an annual inspection done by a professional.
Monthly (User checks)
- Confirm the extinguishers are in the right location and easy to access
- Inspect the tamper seal and safety pin
- Inspect the extinguisher for signs of damage, corrosion, or leaks
- Ensure the label is visible
Annually (Professional service)
- Conduct a visual inspection of cylinder, hose, and horn
- Weigh extinguisher to check for CO2 loss
- Check for damaged or worn parts
- Review service history and update records
You must replace your CO2 extinguisher after any use, even if you’ve used only a small amount, as the extinguisher won’t work when you need it again. It’s also a good idea to keep a maintenance log.
To recap, CO2 fire extinguishers are a reliable choice for tackling electrical fires, especially in settings where avoiding mess or equipment damage is a priority. They can be used to tackle Class B fires too. However, they’re not suitable for all fire types, and using them incorrectly can lead to greater risk.
With the right placement, regular maintenance, and an understanding of when (and when not) to use them, CO2 extinguishers can play a vital role in your fire safety strategy.
