Types of Fire Extinguishers
Fire extinguishers are a necessary part of fire safety and protection. In order to ensure that you keep your surroundings safe, it is important to ensure that you utilise the right type of fire extinguisher for your unique situation. There are different types of fire extinguishers that serve a variety of purposes and these will be covered in this article to ensure that you are adequately protected. There are six types of fire extinguishers that will be outlined here, each suitable for a different class of fire.
Categories of Fire
Let us first take a quick look at the different categories of fire, this should help you to understand when is best to use each type of extinguisher.
- Class A – fires involving solid materials such as wood, paper or textiles.
- Class B – fires involving flammable liquids such as petrol, diesel or oils.
- Class C – fires involving gases.
- Class D – fires involving metals.
- Class E – fires involving live electrical apparatus.
- Class F – fires involving cooking oils such as in deep-fat fryers.
Water – Category A
Water fire extinguishers are suitable for fires involving solid combustibles (category A), these include wood, textiles and paper. When using this type of fire extinguisher it is important to avoid electrical equipment, as this is another potential fire risk. Water based fire extinguishers are also not for use on burning fat or oil fires.
To use a water fire extinguisher, point the jet at the base of the fire and move it around the area, ensuring that all of the fire is extinguished.
Water based fire extinguishers work on solid combustible fires as they cool down the fuel’s surface.
There are a few different types of water based fire extinguishers, which is worth noting. Some have additives added to the water and this makes them overall more effective. This is due to the fact that this extinguisher sprays, rather than jets, covering a larger surface area, and also the addition of surfactants helps to penetrate the combustibles, cooling them more rapidly.
Another category of water based fire extinguishers is the Water Mist Extinguisher. These extinguishers contain de-ionised water and are capable of fighting class A, B, C and F fires (solid materials, flammable liquids, gases and cooking oils/fats).The mist emitted from the extinguisher suffocates and cools the fire. It also helps to create a barrier of sorts between the person using the extinguisher and the fire itself, therefore improving safety.
AFFF Foam – Categories A, B, E
AFFF fire extinguishers are used for fires that are burning solids or liquids. They are not suitable for use on fires stemming from oil/fat. AFFF Foam extinguishers are used in the same way as water based extinguishers, in that you aim the foam at the base of a solid combustible fire and cover the area of the flames, ensuring that all of the fire is extinguished. However, if the fire is a liquid, you need to aim to build enough foam to cover the surface of the liquid. Therefore, it is a good idea to aim the foam above the flames, or into a corner of the flames if the fire is in a container.
AFFF Foam extinguishers work by forming a barrier on top of the burning liquid, preventing the interaction between the flames and the fuel. The foam prevents reignition from occuring due to the foaming agent.
Carbon Dioxide (CO2) – Categories B and E
Carbon dioxide fire extinguishers are best used for electrical fires, as CO2 is not a conductor of electricity. They were originally intended for use on flammable liquid fires, but have since proven to be very effective on electrical fires. As a result of this, they are commonly used on large computer servers.
When using CO2 extinguishers it is important that you take care as they are not recommended for use in close quarters, as it can lead to suffocation. Not only that, but it is important to remember that these extinguishers are not to be used on category F (fat/oil) fires as it can carry the oil out of the container, therefore spreading the fire. Areas should be ventilated as soon as the fire is under control in order to avoid asphyxiation.
To use a CO2 extinguisher you should point the horn at the base of the fire and keep it moving until the flames have extinguished. The extinguisher works by literally suffocating the fire, as the CO2 displaces the oxygen in the air. As the CO2 dissipates there is a risk that the fire will reignite, so be aware of this.
ABC Powder – Categories A, B, C and E
ABC Powder extinguishers are very versatile and can be used on many different categories of fires, including organic materials, liquids, gases and electrical fires. They are not to be used on oil/fat fires.
There is a slight danger of inhalation of the powder when it is used within buildings and it is therefore not recommended for use within enclosed areas. To use this type of extinguisher point the horn at the base of the flames and move it in a rapid sweeping motion, driving the flames backwards.
ABC powder is effective as it cools the fire down so much that the chemical reactions can no longer take place. However, there is a chance that the flames will reignite shortly after the powder is administered when the components heat back up.
Wet Chemical – Categories A and F
Wet chemical fire extinguishers are ideal for use on cooking fires including oils and fats. They can also be used on category A fires. The wet chemical extinguisher is simple to use and should be applied in a slow circular motion to the fire, eventually the fat/oil will become a soapy-like liquid and this shows you that the fire is adequately extinguished. Application should be gentle in order to prevent any oil from splashing and the fire spreading.
Wet chemical extinguishers work by providing a blanketing effect, similar to foam extinguishers. They usually contain some form of chemical, such as potassium acetate, that helps to cool and blanket the fire.
It is important that you have the right type of fire extinguisher for your own situation. But remember that safety is key and anybody expected to use a fire extinguisher should have the proper training in order to ensure that they fight the fire effectively.