How Carbon Dioxide Extinguishers Work:

If you remember the fire triangle from school, fire needs oxygen, fuel and heat, remove at least one of these three and the fire will extinguish. And in this case, CO2 fire extinguishers work by displacing oxygen around the fire, thus suffocating it and preventing further combustion. It does not sufficiently cool the fire itself so therefore they are not certified to extinguish Classes A – solid combustibles. Other fires they are not certified for are Class C – Flammable gases, and D – special metals. Because of the pressure of discharge, they are not suitable for Cooking oil and fat fires.

Carbon dioxide is stored in a liquid form, under high pressure within the extinguisher and is released as a gas when the extinguisher is discharged. The rapidly expanding CO2 gas creates a cold fog that smothers the flames. But a word of warning during this rapid expansion of gas. Around the nozzle, the horn gets incredibly cold, and if the user was to touch the horn at this stage they would suffer freeze-burns to the skin. Therefore, they must never touch the horn at all during its use or shortly afterwards.

In addition, since it creates a rapid increase of CO2 within the vicinity, displacing the oxygen, it can leave any persons in close proximity, in front of the discharging extinguisher, short of breath and even potentially leading to asphyxiation. Should the horn have been removed or is faulty, it creates such high pressure from the nozzle that the complete extinguisher can be propelled with some force in the opposite direction, including into the air. For this reason, if the user is aware of any damage, the extinguisher must not be used until it is professionally inspected and repaired or a replacement has been carried out.


Carbon Dioxide fire extinguishers have a typical lifespan of 10 years, but they must be professionally serviced at least once a year by a qualified technician during that time. At the end of those 10 years, it is possible that the unit can be recycled, but this must only be undertaken by those qualified to do so. We recommend all users must inspect each extinguisher to ensure that the log is complete showing installation and all annual inspection and servicing dates up to the present day.

How to use a CO2 extinguisher

Always remember, all handheld fire extinguishers are intended for use on small fires before they become established. If the fire is too established, then you should not attempt to extinguish it yourself but escape to safety (using the extinguisher if necessary to aid escape), and follow the fire services’ advice to get out and stay out and let them deal with the fire.

Firstly, ensure that it is the correct type or class of fire. Remember – it is only certified for fires of flammable liquids eg petrol, oil, diesel alcohols etc (this excludes any cooking oils or fats) and electrical fires. These include electrical sockets, wiring and appliances etc BUT do not include lithium rechargeable batteries.

If the extinguisher is away from the fire, carry the extinguisher to a point at a suitable distance from the fire. When carrying, do not run, hold it with your fingers around the nozzle but not squeezing the trigger. The pin should still be in place that this point.

Always ensure you are between the fire and your escape route, never allow the fire to block that escape route. If necessary, unfold the horn to approx. 45o to 60o degrees – Do this BEFORE you start to discharge the extinguisher. Remove the pin, holding the trigger only – NEVER touch the horn at this stage. Ensure there are no persons potentially in the path of discharge. With the horn aimed at the base of the fire, squeeze the trigger allowing a short, rapid burst of the discharge. Stop, and inspect to see if the fire is out, if it is not repeat the short rapid bursts until you are confident the fire is out.

The typical total discharge time of a CO2 extinguisher weighing around 5lkg is just 10 seconds so by doing those short bursts you are maximising those 10n seconds.

Remember even after use the horn will still be freezer cold so don’t touch it. If you did manage to extinguish the fire with just 2 to 3 seconds of discharge, don’t just place the extinguisher back in service for another day, it must be fully recharged and serviced by a professional technician.

Advantages of Carbon Dioxide Fire Extinguishers:

  1. Clean Extinguishing Agent: Carbon dioxide does not leave any residue, making it a preferred choice for areas with sensitive electronic equipment, laboratories, server rooms, and more.
  2. Non-Conductive: CO2 extinguishers are non-conductive, making them safe for use on electrical fires.
  3. No Damage to Materials: Since CO2 doesn’t react with materials or leave behind corrosive substances, it’s suitable for a wide range of fire types.
  4. Rapid Action: Carbon dioxide extinguishers act quickly, limiting fire spread and potential damage.
  5. Environmentally Friendly: CO2 is a natural component of the atmosphere and does not contribute to ozone depletion or environmental harm when released.

Considerations and Safe Usage:

  1. Limited Cooling Effect: CO2 extinguishers do not provide long-lasting cooling like other extinguisher types. Ensure proper fire suppression to prevent re-ignition.
  2. Ventilation: Adequate ventilation is essential after using a CO2 extinguisher to allow the gas to disperse safely.
  3. Cold Burns: Direct contact with the released CO2 gas can cause cold burns. Hold the extinguisher’s horn or nozzle while discharging to avoid contact.
  4. Recharging: After use, CO2 extinguishers need to be refilled and pressurized. Regular maintenance is crucial to ensure they are always ready for action.

Watch our brief video guide about Carbon Dioxide Fire extinguishers – How to use safely, types of fires its certified for and what not to do!