When defining fires, you can divide them into six classes, and each needs to be dealt with differently. This is why there are various types of fire extinguishers. You might be under the impression that there is only one type of extinguisher that you can just use for all types of fire, but buildings will probably have different fire extinguishers for the type of fire they’re more likely to encounter there.
Read on for a guide to classes of fire, types of extinguishers and the types of fire they can combat.
Classes of Fire
Fire is defined as the process in which substances combine chemically with oxygen from the air, however, not all fires are the same. This is because fires can be caused by a variety of different things and behave in different ways. That is why we organise fires into six classes, so we know exactly how to combat them depending on the class they are in. . These classes are:
Class A Fires - Combustible Materials: This type of fire is caused by flammable solids such as fabric, paper and wood.
Class B Fires - Flammable Liquids: Class B fires are caused by flammable liquids such as paint, petrol or turpentine.
Class C Fires - Flammable Gases: This type of fire is caused by flammable gases such as butane, hydrogen or methane.
Class D Fires - Combustible Metals: Class D fires are caused by chemicals such as aluminium, magnesium, lithium and potassium.
Electrical Fires: This is fires caused by electrical equipment such as computers and generators. Once the electrical item is removed, the fire changes class.
Class F Fires - Cooking Oils: Class F Fires are caused by cooking oils, typically a chip-pan fire.
Fire Related Hazards
Fires are very dangerous whatever the class, causing a range of hazards from the heat, smoke, lack of oxygen and damage to the surrounding environment it's located in. The flames from a fire can burn your skin as well as your eyes and inside your body. Burns can be very serious, even life-threatening. They are extremely painful and can leave you with permanent scarring.
Smoke inhaled during a fire can cause a lot of damage to the inside of your body, such as your lungs. In case of a fire, you must be extremely careful not to breathe in too much smoke, as smoke inhalation is actually the leading cause of fire-related deaths. The oxygen in a space is used up quickly during a fire, as it is one of the three components needed for a fire. You should therefore try to exit a space with a fire as quickly as possible because you might soon not have enough oxygen to breathe properly.
Finally, fire can cause extensive damage to the surrounding environment. This could be enclosed to a small area if the fire is dealt with quickly, but could extend further if the fire is allowed to grow. Fire can affect the foundations of buildings and cause them to collapse if left undefeated.
Types of Fire Extinguisher
No one extinguisher can combat every type of fire, so it is important to understand what type of fire is most likely in a location so that an extinguisher can be supplied in case of an emergency. The five types of fire extinguishers are Water, Foam, Dry Powder, CO2 and Wet Chemical. There are also different versions of both the Dry Powder and Water extinguishers, bringing the total to eight. Before we get into more details, here is a quick guide on what type of fire each extinguisher can be used against.
Class A - Water, Foam, Dry Powder, Wet Chemical
Class B - Foam, Dry Powder, CO2
Class C - Dry Powder
Class D - Flammable Metals
Electrical - Dry Powder, CO2
Class F - Wet Chemical
As you can see Class A fires can be dealt with by a variety of extinguisher types, but Class C, D and F require a specific type of extinguisher to help combat the fire. Every property should assess the risk of the various classes of fire that could affect them and then outfit their space with extinguishers accordingly.
Water Extinguishers
Water fire extinguishers are the most common type of extinguisher you will find, used for Class A fires. They work by using water to cool the fuel that is burning, causing it to burn slower until the flames are fully extinguished. You can tell a Water extinguisher by the bright red label. It should be used for fires burning organic material, such as paper, wood, fabric, coal, cardboard and other textiles.
This is the only type of extinguisher that should only be used for one class of fire. You shouldn't use this type of extinguisher for kitchen fires, flammable liquids or gas, or any fires involving electrical equipment. They are used in most buildings, anywhere constructed from wood or other organic material, or at premises where organic materials can be found.
Water extinguishers can be divided into two types: water spray extinguishers and water mist extinguishers. Water spray extinguishers use a spray nozzle to cover a greater surface area, while water mist extinguishers use a type of nozzle that releases microscopic water particles. They suffocate the fire and create a wall of mist between the fire and the user, helping to reduce the feeling of heat.
Foam Extinguishers
Foam extinguishers are most often used for Class B fires but are also used to combat Class A fires. Recognisable by their cream label, they can be used against organic material and also flammable liquids like paint or petrol. The foam creates a barrier between the flame and the fuel, helping to extinguish the flames quickly.
They should be used in buildings where organic material is found and where flammable liquids are stored. They should not be used for flammable metals, kitchen fires or fires involving electrical equipment.
Dry Powder Extinguishers
Dry Powder extinguishers are commonly referred to as ABC extinguishers, as they are used for combating Class A, B and C fires and are recognisable by a blue label. They can also be used on some electrical fires on equipment up to 1000v and specialist dry powder extinguishers can be used for flammable metals. L2 extinguishers can only tackle lithium fires while M28 extinguishers can be used for all other flammable metal fires.
Dry Powder extinguishers are not recommended for use in enclosed spaces, as the powder is easily inhaled and difficult to clean up. They work similarly to foam extinguishers, smothering fire by forming a barrier between the fuel and the oxygen source.
You should have Dry Powder extinguishers if you’re a business using flammable gases, a premise where welding takes place, premises with large boiler rooms or liquid petroleum gas dispensing plants.
Carbon Dioxide Extinguishers
Carbon Dioxide (CO2) extinguishers are mostly used for electrical fire risks but can also put out Class B fires. They have a black label and work by displacing the oxygen the fire needs to burn, therefore suffocating it.
They should be located at premises with electrical equipment, especially those with server rooms or large amounts of electrical equipment.
Wet Chemical Extinguishers
Wet Chemical extinguishers are designed to be used on Class F fires, involving fats and cooking oils. They can also be used for Class A fires but it is much more common for other extinguisher types to be used for this.
They have a yellow label and work by creating a layer of foam on the surface of the burning oil or fat, cooling it down and preventing oxygen from fuelling the fire. They are most commonly used in commercial kitchens or anywhere where food preparation is done.
Fire Extinguisher Regulations
The UK Fire Extinguisher regulations mean you need to have the correct type of extinguishers on your business premises. Along with the type, you also have to ensure that they are the right weight and size. The standards are that you should have a minimum of two Class A fire extinguishers on every story of a building.
Any premises with electrical equipment must have a CO2 extinguisher on-site, meaning you will often see two extinguishers together in a building, one for Class A fires and one for electrical fires. Fire extinguishers are usually placed at exits and fire alarm call-points. You should never be more than 30 metres from an appropriate extinguisher.
EK Fire Protection Ltd
If you need fire extinguishers supplied to your property to meet regulations, get in touch today with EK Fire Protection Ltd. We can carry out a fire risk assessment for your premises, informing you of the type of extinguishers you need and where to place them.
So get in touch today by calling 01304 210909 to talk through your requirements with a member of our friendly and knowledgeable staff. To find out more about the range of fire protection services we offer, visit our website now.
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