What are the different types of Fire Extinguishers?
There are different kinds of Fire Extinguishers depending on the type of fire there is.
Not one type of extinguisher is good for all fire types. Each extinguisher has their own unique contents that allow the extinguisher to be effective on the type of fire it puts off. So that we may better distinguish one extinguisher type from another, it is, therefore, best to know first the classes of combustible materials there are that can cause and sustain fire to our immediate surroundings.
There are six classes of fire based on Asian standards. This list, however, may differ slightly from the European Standards and American Standards where each has only five classes. Each category has been classified according to what type of material they burn and how resistant or reactive these materials are to fire. They are:
- Class A fires comprise of materials that are solid and organic in nature. These materials include rubber, cloth, wood, paper and plastics that are easily combustible.
- Class B fires comprise of liquid or fluid materials. These materials include paints, wax, petrol, thinners, diesel and melt-able plastics.
- Class C fires comprise of materials that are made of flammable gases. Considered as part of Class B for American Standards.
- Class D fires comprise of materials that are made of burnable metals. These materials include metals made of sodium, aluminum, potassium, and
- Class E fires comprise of flammable electricity. This class of fire is generally not included in European Standards.
- Class F fires comprise of cooking oils and fat fires. Known as Class K in American Standards.
Now that we have identified the kinds of fire that occur by class, we can now easily differentiate the different fire extinguishers there are, based on the class of fire they put off.
These are extinguishers that are excellent for putting off burning wood, soft furnishings, burning paper or in short, Class A fires. Its fire-fighting process happens by allowing the water contained in the extinguisher to sip in, into the burning material, allowing it to cool then it puts off the fire. This type of extinguisher does not generally contain harmful chemicals, and they are quite slow in putting off the fire. Its containers are usually heavy and large because of the liquid it contains, which is the primary source of its firefighting antidote. Since water is a conductor of electricity and is an electrolyte, moderate precaution should be observed when using this type of extinguisher as it may post higher risk when used on exposed power cables.
With recent upgrades, there are some water extinguishers that have been released with additives. These variants of the water extinguishers were made as an alternative to be able to safely put off the fire of Class A category but with possible accidental exposure to electricity. This allowed for the smaller and lighter water extinguisher containers to be created that are best used within households for easy and immediate reach. Similarly, these are the best extinguishers to be stored in households with children due to its non-toxic contents, should there be a possibility of accidental discharge.
Foam Fire Extinguishers
Also known as AFFF or Aqueous Film Forming Foam, these extinguishers are characterized by the foamy film they create over the fire once released from the extinguisher. It then deoxygenates the burning surface thereby allowing the fire to die down. The foam created by the extinguisher covers like a carpet, blanketing the burning liquids that are of Class B fire category. These types of fire include flammable liquids or soft furnishings of man-made fibers that can melt and liquidize when subjected to heat. These extinguisher foams can penetrate porous materials, and cool down the fire by allowing the water in the foam to evaporate. With successful dielectric tests, these types of extinguishers are found to be safe to use on electrical equipment, given that they are released from a 1-meter safety distance. With such distance, it is expected that the electrical equipment will be damaged by the extinguisher liquid.
CO2 (Carbon Dioxide) Extinguisher
These types of fire extinguishers make use of pressurized CO2 gas hence they leave no residue. They are best used for fires that are made of burning liquids or Class B fires. Similarly, they are also the best extinguishers of choice for taming computer equipment fires or electrical appliances fires, as the carbon dioxide does not cause a short circuit to the system nor does it damage the electrical items/equipment itself. It is pertinent, however, to remember that the source of the fire must be immediately removed when using CO2 extinguishers, as there is a danger of re-igniting the source of fire once the CO2 gas has flown off into the air or if the burned materials are still very hot. Additionally, it is a good precaution that when buying CO2 extinguishers, one should choose those that are tailored with double-lined swivel, so as to avoid freezing your fingers. The best choice of CO2 extinguishers is those that are with frost-free horns. It is also good to note that CO2 extinguishers should not be used for deep fat fryers on fire, as the strong gas jet from the extinguisher can carry the burning fat out of the deep fryer and into the room.
Powder Fire Extinguishers
Also known as the ABC powder extinguishers, these types of extinguishers are best in fighting off Class A, B, and C fires and are generally found to be effective and efficient with its fire-fighting capacity. On the contrary, since this type of extinguisher does not soak into materials nor does it have a cooling effect on the burning item, it can, therefore, cause the fire to re-ignite if the fire is not properly extinguished. This type of extinguisher cannot be used in small confined spaces due to the risk of extinguisher powder inhalation. Amidst its high effectivity to putting off the fire, clean up after using the powder extinguisher is very difficult. The powder, when subjected to putting off burning items, can cause damage to carpets, surfaces of computers, or surfaces of soft furnishings and the like. Due to the higher risk of damage and clean up problems in using powder extinguishers, it is best to discern first if this is the right extinguisher to be purchased for use, over the less powerful and often more expensive foam water extinguishers.
For household use, it would be best to read the labels that state that you are not just buying BC rated powder fire extinguishers. These types of extinguishers are not good for solids on fire. These BC type of extinguishers are however usable for putting off the fire on cars.
Another form of extinguisher, almost similar to the CO2 extinguisher is the Water Mist Extinguisher. Also known as the dry water mist extinguisher, these extinguishers set off a jet of fine mist that wets and cools the surfaces of burning items. The mist, that slowly evaporates into the air expands over the burning area which wets and cools down the burnt surface, producing steam that expels the oxygen out. This process thereby deoxygenates the burning area and kills the fire. Since the water droplets are very light and do not sink or sip underneath the surface of burning liquids, those explosive reactions, similar to that of ordinary water extinguishers on burning oil or fat, are avoided. With this, we can say that water mist extinguishers are good in putting out fat fires. A variant of water extinguishers like that of the UltraFire extinguisher, contain only de-ionized water to inhibit conduction of electricity. Therefore, when used on fire where there are electrical items burning, this can be a better choice. Just remember that this type of extinguisher can only be used in homes and offices with burning items of 1000 Volts at a safety distance of 1 meter. We can say therefore that water mists are really broad range extinguishers that are safer to use in homes.
Wet Chemical Fire Extinguishers
These extinguishers are designed for kitchen fires that are due to burning oil and deep fat fryers or also known as Class F fires. This type of extinguisher has a specially elongated applicator lance that allows the spread of a cooling carpet of foam, on top of the burning oil or fat. These types of extinguishers can also be an alternative for Class A fires. However, its fire-fighting capacity for general risk fires is not very strong and efficient.
Optionally, a fire blanket generally kitemarked can be laid over the pan of the burning oil or fat. The pan must then be left with the blanket down and never lifted to check the oil or taken outside of the house. Doing so may re-ignite the fire due to the introduction of oxygen on the heated oil. It is also never a good idea to use pressurized water, CO2, powder or foam extinguishers on fires of burning fat or oil. The release of the pressurized jet can trigger the burning oil to be carried out of the pan causing more damage to other surfaces surrounding the area or will make the fire quite larger to mitigate. A better alternative for oil or fat fires would be Dry Water Mist extinguishers as these extinguishers release a fine mist that does not enter the hot oil but only suffocates the supply of oxygen on the oil surface while cooling the liquid, thereby creating a safer layer between the fire and the user of the extinguisher.
We hope you found this information useful if you would like to discuss this in more detail please contact us and we are always happy to help.