Introduction to CO2 fire extinguishers

CO2 fire extinguishers contain carbon dioxide gas (CO2) under very high pressure (about 55 bar at room temperature) and can be easily recognised by their flute-shaped discharge horn. CO2 extinguishers are colour coded with a black field on the otherwise red extinguisher.

CO2 fire extinguishers suppress fires by replacing oxygen, without which there can be no fire, with the inert CO2 gas. Although the CO2 is very cold when it comes out of the extinguisher, this does not make it a suitable choice for tackling Class A fires, such as solid combustibles like paper, wood and fabrics. Class A fires require water-based extinguishers that penetrate/saturate the burning materialwork to prevent re-ignition. A still smouldering Class A fire could simply re-ignite once the CO2 gas has dispersed.

CO2 extinguishers are these days mainly used in office environments, where they can be used to extinguish fires in electrical equipment.  This is due to carbon dioxide being non-conductive and not leaving any harmful residue that may contaminate sensitive circuitry. Please note, though, that the use of CO2 gas on electronics can still damage the circuits through static or temperature shock.

CO2 extinguishers can also be used by experienced operators on Class B fires which consist of flammable liquids such as petrol, oil and diesel, (not including cooking oil).

The properties of CO2 also make the extinguisher a good protective fire fighting device in places like laboratories, clean rooms, engine compartments, generator rooms, boats and flammable liquid storage spaces.

It is not easy to verify whether a CO2 extinguisher is still filled or has suffered a loss in pressure and content. At a filling pressure of 55 bar and room temperature the CO2 in the extinguisher is neither a liquid nor a gas. What this means in practice is that you cannot hear any ‘sloshing’ when you are shaking a CO2 extinguishers. It just feels as if it were empty! The only way to verify that the extinguisher is still charged is to measure its weight and compare it with its manufactured weight stamped on the cylinder. You need very precise scales for this. Also, the discharge horn of the extinguisher has to be removed for this purpose. This is dangerous and should not be done without prior training, as an accidental discharge without the horn can lead to serious injury. The Horn acts as a pressure reducer; when it is removed the CO2 extinguisher discharges like a rocket should the handle be operated!

When ordering CO2 extinguishers, make sure you buy a model with a frost-free horn, as the horn gets so cold that skin could stick to it.

Call our customer hotline now on 0800 6126537 to find out more about the benefits of CO2 extinguishers or take some time to explore our web pages and see our impressive range of affordable fire safety products in greater detail.

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