In firefighting, all fires are classified by the materials that cause their breakout, and there is a fire suppression method associated to each of these fire classes. The fire classes are marked type A, B, C, D and K in the American classification system, A, B, C, D and F in Europe and A, B, D and F in Australia. And now let’s see a short overview the basic extinguishing substances and some fire types they are used for.
The most common fire suppression substance is water. It is used in most fire extinguishing systems, but is efficient only with type A fires, that is, the ones caused by the ignition of solid materials like wood or paper. Installing integrated water-based systems in buildings is very expensive, because of the large quantities of water necessary to operate the system and due to the necessary investments into pipes, valves or drainage systems.
Dry chemicals can be used for extinguishing more than one type of fire. They are equally effective with class A, B and C fires, which means that they can be used not only with the above-mentioned A class fires caused by ordinary combustibles, but also with flammable liquids and flammable gases. Multi-purpose dry chemicals are very efficient, that is why they are frequently used as portable extinguishers in schools, offices or hospitals, but they cause corrosion in the presence of a moist atmosphere, so the residues must always be cleaned up after use. There is another type of dry extinguishing agent called regular dry chemical that is non-corrosive and is mainly used in garages and laboratories.
Another common fire suppression agent is carbon dioxide. It puts out the fire by cutting the oxygen supply. It is environment friendly and can be equally used for type B, C and D/E/F fires, that is, for fires caused by the ignition of flammable liquids, flammable gases, electrical fires and kitchen fires in places like computer rooms, processing plants, laboratories or restaurants. However, carbon dioxide cannot prevent re-ignition and it is also dangerous for humans, because it causes dizziness or even loss of consciousness if inhaled for longer than a few minutes.
Halotron is another multi-purpose fire extinguisher. This liquid vaporizes after usage, so no clean-up is necessary and it is equally efficient in putting out class A, B and C fires. However, harmful gases can form during usage, so it requires special protective equipment.
Choosing the right fire extinguishing agent is key to putting out fires and every building must be equipped with basic fire suppression devices.
Source by Mary L Smith