There are different types of fire extinguishers because there are various types of fires. Each extinguisher is suitable for fighting certain types, and it’s important for you to know the differences if its your job to fight fires at work. Being able to immediately distinguish which extinguisher you need in an emergency apart could make a lifesaving difference.
What Are the Different Classes of Fires?
Fires must be fought carefully depending on the materials involved. That is why they have been classified in 6 different categories:
- Class A – Fires that involve solid flammables and dusts, such as wood, plastics, paper and cardboard, fabric and textiles, and dusts such as grain dust and flour.
- Class B – Fires that involve flammable liquids, such as gasoline, petroleum oil, paint, or diesel.
- Class C – Fires that involve flammable gases, such as propane, butane, or methane.
- Class D – Fires that involve combustible metals, such as magnesium, lithium, sodium, potassium, titanium, or aluminium.
- Class F – Fires that involve cooking oils and fats, such as vegetable oil, sunflower oil, olive oil, maize oil, lard, or butter (typically those used for deep-fat fryers).
- Although it is not recognised as a separate class of fire in Europe, electrical fires that involve live equipment and electrical sources are also a type you should bear in mind (think of it as an informal Class E; ‘E’ for electric to help you remember).
What Are the Different Types of Fire Extinguishers?
There are five main types of fire extinguishers:
- Carbon Dioxide (CO2).
- Wet chemical.
1. Water Extinguishers
There are two types water extinguishers: water spray and dry water mist.
Standard water extinguishers
These will be solid red and will have the word ‘water’ or ‘aqua spray’ printed across them in white text. They are your classic model: they dispense water at a high pressure to extinguish flames.
Water extinguishers are only suitable for class A fires, which means they can fight fires that involve wood, cardboard, paper, plastics, fabric and textiles, and other solid materials.
Warning: do not use water extinguishers on burning fat and oil fires and electrical appliances.
Dry water mist extinguisher
These types of fire extinguishers will be solid red and will have the words ‘water mist’ printed within a white rectangle.
Dry water mist extinguishers are unique in that they can combat almost all types of fires, including class F fires that are usually difficult to attack. The extinguisher’s nozzle converts water into ‘dry’ microscopic particles, which are then drawn into the fire and simultaneously cool and suffocate it to extinguish the flames.
They are also effective for fire-fighting because they form a safety barrier between the user and the fire – which repels some of the heat – and do not leave hard-to-clean residue behind.
2. Powder Extinguishers
There are three types of powder extinguisher: ABC powder, M28 powder, and L2 powder.
ABC powder extinguisher
These types of extinguishers will say ‘powder’ in white text over a blue rectangle, and underneath the rectangle will be written ‘ABC powder’.
As their name suggests, these are designed to combat class A, B, and C fires – those involving solids, liquids, and gases. The powder acts as a thermal blast that cools the flames so burning cannot continue. Due to their non-conductive nature, they are also suitable for fighting electrical fires. However, they do not effectively penetrate the spaces in equipment easily, so the fire could still re-ignite.
M28 and L2 powder extinguishers
These types of extinguishers are best identified by their unique hose, though they will also say ‘powder’ in white text in a blue rectangle. Do not confuse these with the ABC powder extinguishers, as they are not designed for class A, B, or C fires. They will state below the rectangle whether they are M28 or L2.
M28 and L2 are unique extinguishers in that they are designed for tackling Class D fires – those involving combustible metals including swarf or powder, which are often produced in engineering factories. Metals includes lithium, magnesium, sodium, or aluminium, for example.
3. Foam Extinguishers
Foam extinguishers are identifiable by the word ‘foam’ printed within a cream rectangle on their bodies. They are primarily water based but contain a foaming agent, which has rapid flame knock-down and a blanketing effect. It smothers the flames and seals vapours so that re-ignition cannot occur.
They are suitable for fighting class A and B fires.
When used against class A fires, the user can simply point and spray. However, when used against class B fires – those with flammable liquids – they should not be sprayed directly into the liquid. This could cause the fire to be pushed and spread to surrounding areas. The best method of application is to spray the foam nearby so that it can build up and flow across it.
4. Carbon Dioxide (CO2) Extinguishers
These types of extinguishers can be identified by the text ‘carbon dioxide’ or ‘CO2‘ printed in white on a black rectangle. They also have a distinct type of hose.
Carbon dioxide extinguishers are used for combating class B and electrical fires – they suffocate the fire by displacing oxygen in the air. Because they do not leave any substances behind and so minimise damage done to equipment, unlike other extinguishers, they are particularly useful for offices and workshops where electrical fires may occur.
5. Wet Chemical Extinguishers
These types of fire extinguishers are identifiable by the words ‘wet chemical’ printed across a yellow rectangle. It also has an extended hose that you can hold and point, which is useful when fighting fires on a kitchen top.
Wet chemical extinguishers are designed for combating fires that involve class F fires. They are effective because they are capable of stopping fires that are of an extremely high temperature, particularly cooking oils and fats. They also discharge gently, stopping the burning oils and fats from being pushed and splashing to surrounding areas or even the user.
Fire extinguishers are an important addition to fire safety measures, as they can help to stop small fires. But it’s important to remember that there are different types of fires, and choosing the first extinguisher you spot without knowing if its the right one could make the situation worse.