There are 7 different commonly used fire extinguishers, each suited to tackling a different type of fire. These include water, foam, powder, co2, wet chemical and clean agent fire extinguishers.
In this Article:
What is a Fire Extinguisher?
A fire extinguisher is a handheld device that is used as fire protection to extinguish and control small fires. The Regulatory Reform (Fire Safety) Order 2005 provided by the Health and Safety Executive (HSE) states that businesses require a minimum of 2 Class A fire extinguishers on each floor in a building which refers to solid combustibles such as paper, wood and textiles.
The 7 Types of Fire Extinguisher
There are 7 common types of fire extinguisher that are filled with different materials that are effective against different fuel sources. It is vital that the correct fire extinguishers are installed into buildings depending on the different types of fuel which can start a fire also known as the classes.
The 7 types of fire extinguisher are:
Water
Water is the most common liquid used in fire extinguishers and sometimes may include other additives or wetting agents to help increase the extinguisher’s effectiveness against fire. However, water fire extinguishers are unsuitable in freezing conditions as the water inside will freeze and will stop the extinguisher from working. Some will contain antifreeze to stop this from happening.
When to Use Water Fire Extinguishers
A water fire extinguisher has a Class A rating
which involves fires caused by solid combustibles
such as paper, wood and many plastics.
When to Not use a Water Fire Extinguisher
Water fire extinguishers should not be used on fires caused by flammable liquids, flammable gases or flammable metals as well as electrical fires unless they are di-electrically tested.
Fire Extinguisher Label Colour
Water fire extinguishers have a signal red label.
Water Mist
Water mist fire extinguishers use clean, deionised water which is discharged through spray nozzles that turns the water droplets into microscopic particle spray to create the mist which is non toxic and non conductive. The mist is used to cool and suffocate the fire without causing damage to the surrounding area.
When to Use Water Mist Fire Extinguishers
A water mist fire extinguisher is most suitable for use on Class A, Class B, Class C and Electrical fires. This includes solid
combustibles such as paper, flammable liquids such as petrol, flammable gases such as methane, hydrogen and propane and burning electrical equipment.
Some water extinguishers can also be used for Class F fires which include cooking oil but should not be used on a fire above 5F rating.
When to Not use a Water Mist Fire Extinguisher
Water mist fire extinguishers should not be used on class D fires which include flammable metals such as magnesium and lithium.
Fire Extinguisher Label Colour
Water mist fire extinguishers have a white coloured label.
Foam
There are two different types of foam fire extinguisher; AFFF ((aqueous film-forming foam) and FFFP (film-forming fluoroprotein). They discharge a foam material which is used to suffocate the fire by blanketing the fuel surface and it can also separate the flames from the fuel source. The foam effectively cools the fuel and surrounding metal surfaces.
When to Use Foam Fire Extinguishers
A foam fire extinguisher is most suitable for use on Class A and Class B fires as the foam
is designed to prevent re-ignition.
When to Not use a Foam Fire Extinguisher
Foam fire extinguishers should not be used on Class C (flammable gases), Class D (flammable metals) or Class F (cooking oil). It should also not be used on Electrical fires unless it has been di-electrically tested.
Fire Extinguisher Label Colour
Foam fire extinguishers have a cream coloured label.
Powder / Dry Chemical
The dry powder fire extinguishers control fires by spraying the powder over the fire which creates a barrier to suffocate and extinguish the fire. This extinguishing agent can be applied straight from the fire extinguisher or can be shovelled on which is referred to as a hand propelled fire extinguisher.
When to Use Dry Powder Fire Extinguishers
A dry powder fire extinguisher can be used on Class A, Class B, Class C and Electrical fires such as organic materials,
flammable liquids and gases and electrical equipment up to 1000v.
Some dry powder fire extinguishers can also be used on flammable metals including magnesium and titanium. The dry chemical chemically insulates Class A fires, smothers Class B fires and isolates the fuel to prevent the spread of fire.
When to Not use a Dry Powder Fire Extinguisher
Dry powder fire extinguishers should not be used for Class F fires involving cooking oil or fires on electrical equipment that uses over 1000v.
Due to the risk of inhalation, dry powder extinguishers should also never be used indoor and small and enclosed spaces.
Fire Extinguisher Label Colour
Dry powder fire extinguishers have a blue coloured label.
CO2
The CO2 fire extinguishers are mainly used for electrical fires as the carbon dioxide displaces the oxygen and suffocates the fire. It can also cool the fuel and the fires are effectively distinguished as there is no oxygen available to feed the fuel. No residue is left behind after use and it discharges a gas cloud with a relatively short range of up to 2.4m.
When to Use CO2 Fire Extinguishers
A CO2 fire extinguisher can be used on Class B and Electrical fires as CO2 is not an electrical conductor.
When to Not use a CO2 Fire Extinguisher
CO2 fire extinguishers should not be used for Class A, Class C, Class D or Class F fires including on fires involving cooking oils.
CO2 fire extinguishers should also not be used in confined spaces as it displaces the oxygen and it will become much harder for people to breathe.
Fire Extinguisher Label Colour
CO2 fire extinguishers have a black coloured label.
Wet Chemical
The wet chemical fire extinguishers are often made up of solutions of water and potassium acetate, potassium carbonate, potassium citrate. Some extinguishers may use a combination of these chemicals which are all conductors of electricity. The extinguishers discharge a fine spray which provides improved visibility and minimum clean-up.
When to Use Wet Chemical Fire Extinguishers
Wet chemical fire extinguishers are specialised for Class F fires involving cooking
oils such as chip pans and cooking fat but can also sometimes be used on Class A. The spray is used to cool Class A fires on solid combustibles and on Class F fires it creates a blanket to prevent re-ignition.
When to Not use a Wet Chemical Fire Extinguisher
Wet chemical fire extinguishers should not be used on Class C, Class D or Electrical fires. It should not be used on Class B fires unless a specialist extinguisher is used.
Fire Extinguisher Label Colour
Wet chemical fire extinguishers have a yellow coloured label.
Clean Agent
Clean agent fire extinguishers are stored as liquid but discharged as a gas. It is not electrically conductive or volatile and will not leave residue behind. Clean agents interrupt the chemical reaction and remove the heat to extinguish the fire.
When to Use Clean Agent Fire Extinguishers
A clean agent fire extinguisher can be used on Class A, Class B and Class C fires as well as certain Electrical fires as it is non conductive.
When to Not use a Clean Agent Fire Extinguisher
Clean agent fire extinguishers should not be used on Class D or Class F fires and should also not be used in windy conditions as it may be harder to extinguish the fire.
Fire Extinguisher Label Colour
Clean agent fire extinguishers have a green coloured label.
The 6 Classes of Fire
There are 5 different classes of fire based on the fuel source that causes the fire. The class off fire is used to determine what equipment is use to tackle it.
Below is the 6 different classes of fire and what fuel source it is designed to extinguish:
Class A | Combustible solids including paper, wood, plastics and textiles. |
Class B | Flammable liquids including petrol, diesel, paraffin and other spirits. |
Class C | Flammable gases including propane, butane, methane and hydrogen. |
Class D | Flammable metals including magnesium, lithium, aluminium and sodium. |
Class F | Cooking oil or fat including deep fat fryers and chip pans. |
Electrical | Electrical has since been added to the classes as it has become a common cause of fires involving computers, heaters and any other equipment that uses electricity. |
Fire Extinguisher Certification
Once the fire extinguishers are installed into a building or business, the fire extinguishers must be serviced and provided with certification as proof that they have been inspected and will work properly in the case of a fire emergency.
This means that all fire extinguishers on the premises must be commissioned to service before they are fit for use. This servicing will assess if the fire extinguishers are fit for purpose, identify any defects or issues, check that the extinguisher is undamaged and safe to use.
Fire extinguisher certification should also determine that the extinguishers are fitted correctly and placed in the safest location and at the correct height.
Other Fire Safety Equipment
To accompany fire extinguishers in all buildings and businesses, there are other fire safety equipment which can be used including:
Fire Alarms – these are used to warn people when a fire starts. They won’t help to stop the fire but will detect it early and help people evacuate to safety in time.
Fire Blankets – these are made from fire resistant material and can be used to smother small fires by removing all of the oxygen. They can also be used to protect people when evacuating a building.
Sprinklers – these are attached to the ceiling and release water when they detect smoke or fire and are an effective way of controlling and extinguishing small fires.
Fire Doors / Fire Escapes – fire doors are made from specially designed material that resist fires and help to contain the spread. Fire escapes provide an accessible escape route for people to leave the building safely and are often highlighted with a clear red sign that says EXIT.
Maintenance of Fire Extinguishers
Fire extinguishers require an annual inspection and service to ensure they are maintained and still fit for purpose.
Maintenance will include:
Visual inspection to check for damage
Check that it hasn’t been used and is still full
Take a pressure gauge reading
Check for blockages in the discharge hose
The maintenance of all fire extinguishers must be carried out by fully trained and competent people.
Fire Extinguisher Storage
The correct way to store fire extinguishers is in accessible places and at a suitable height in which they can be easily reached for in the case of a fire emergency. Mounted fire extinguishers will also help to prevent damage to the container.
Fire extinguishers should be placed near exits in office buildings and near flammable materials such as electric equipment and a minimum of two per floor should always be available to ensure every area of the building is sufficiently covered.
Fire extinguishers are an essential part of fire safety in all buildings and they must be regularly inspected to ensure they still work. Make sure the correct type of fire extinguisher is available for the different classes of fires that can be caused due to the fuel source.
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