Carbon dioxide (CO2) is a colourless and odourless gas. It is about 1.5 times heavier than air and is present in the air we breathe. It is also commonly known as carbonic acid and is used for many other applications.
Fire class suitability
Fire extinguishers with carbon dioxide are only approved for fire class B (flammable liquids).
However, they are also often used to protect sensitive equipment, such as switch cabinets, EDP areas and many more. If the fire is discovered in the early stages, an attempt to extinguish the fire with carbon dioxide can be very useful.
DÖKA offers carbon dioxide fire extinguishers with 2 and 5 kg capacity.
No extinguishing agent residues
Only carbon dioxide fire extinguishers do not leave any extinguishing agent residues when used. This is why these extinguishers are often used to protect sensitive equipment and in food areas. Since carbon dioxide is not electrically conductive, these extinguishers are often used to protect electrical installations. This is despite the fact that carbon dioxide fire extinguishers are only approved for class B fires. Provided the fire is detected in time, an attempt to extinguish it with carbon dioxide fire extinguishers can be successful.
The extinguishing effect of carbon dioxide is based on the sticking effect. 1 kg of liquid carbon dioxide produces approx. 550 l of expanded gaseous carbon dioxide. A concentration of approx. 33 % in the breathing air is necessary for extinguishing. The proportion of oxygen in the air is reduced, the fire is suffocated. Contrary to what is often thought, the cooling effect is practically insignificant. The spreading as snow (as fine as possible) only serves to cause a longer residence time on the source of the fire.
At first glance, this residue-free extinguishing agent seems almost ideal. Unfortunately, however, carbon dioxide fire extinguishers also have some disadvantages.
Thick-walled, relatively heavy high-pressure cylinders made of steel or aluminium are used as extinguishing agent containers. This results in an operating weight of around 15 to 16 kg for a 5 kg fire extinguisher. The use in narrow, poorly ventilated rooms can even be dangerous and the extinguishing performance is naturally not very high either.
Advantages of carbon dioxide as an extinguishing agent:
- No consequential damage caused by the extinguishing agent, absolutely residue-free
- Extinguishing agent is not electrically conductive
- As a natural gas, carbon dioxide is environmentally friendly
Disadvantages of carbon dioxide as an extinguishing agent:
- High device weight (with 5 kg fire extinguishers)
- Low extinguishing capacity
- Use in confined, poorly ventilated spaces can be dangerous