Fire extinguisher types - How to choose, identify, maintain and use firefighting equipment

The catastrophic consequences of fire taking hold cannot be underestimated. Taking time to develop a robust risk assessment and identifying the most suitable firefighting equipment is likely to be time well spent. Here we take a look at the types of fire extinguisher available, how they can be identified and how they should be used.

Who is responsible for fire safety?

In England and Wales, the responsibility for fire safety in a business or other non-domestic premises lies with an employer, owner, landlord, occupier or someone with nominated control of the premises. This person is known as the 'responsible person'.

The responsible person must carry out a fire risk assessment,communicate any risks identified, implement appropriate fire safety measures, plan for an emergency and provide information, instruction and training for staff.

More information can be found on the .gov.uk website . The rules are different in Scotland and Northern Ireland .

How do fires take hold?

For combustion to take place four elements must be present - fuel, heat, oxygen and a chemical chain reaction. Removal of one of these elements will result in the fire being extinguished.

A foam barrier from an extinguisher, for example, will prevent oxygen getting to the fire. Water will lower the temperature below that required for ignition (or by removing or diverting the fuel from a flammable liquid). CO₂ gas will displace oxygen smothering the fire. Using dry powder or vaporising liquid will interfere with the chemical chain reaction by mopping up free radicals.

How are fires classified?

Fires can be classified according to one of six groupings:

Class	Description
Class A	Fires involving freely burning materials, organic solids such as wood, paper, textiles and other carbonaceous materials.
Class B	Fires involving flammable liquids such as petrol, diesels, oils or paraffin. Not alcohol or cooking oil.
Class C	Fires involving flammable gases, such as methane, propane, hydrogen or natural gas.
Class D	Fires involving flammable metals such as magnesium, aluminium or lithium.
Class F	Fires involving combustible cooking media such as fats, oil or grease (such as olive oil, maize oil, lard or butter). These types of fires should be tackled by either a wet chemical or ‘dry water mist’ extinguishers or a fire blanket. Water, powder, foam and CO2 all carry the risk of spreading the burning oil into the room.
Electrical Fires	Fires caused by electrical appliances, such as computers, printers or photocopiers. These kinds of fire can fall into any of the previous classifications depending on what has been set alight.

A range of fire extinguishers are available that can be used on variations of these kinds of fires.

How are fire extinguishers identified?

Fire extinguishers are identified by a colour coding system.

Prior to 1997 the entire body of a fire extinguisher was painted in the code colour.

Later extinguishers must conform to BS EN 3 and will be predominantly red in colour. A coloured band or circle (covering around 5% of the body) is used to denote the coding group.

Extinguishers that use the earlier system of colour coding can still legally be used providing they are otherwise operational.

Fire extinguishers colour coded green are vapourising liquids or Halons and have been illegal (with some exceptions for aircraft and military use) since the end of 2003 as a result of the Montreal Protocol.

What kind of extinguisher should I use on which kind of fire?

Class	Water	Water mist	Foam	Dry powder	Specialist Powder	CO2 Gas	Wet chemical
Class A
Class B
Class C
Class D
Electrical
Class F

What extinguishers do I need and where should they be sited?

Commercial organisations need to undertake a fire extinguishing capability survey, using extinguisher ratings to calculate the numbers and types of extinguishers required. The British Approvals for Fire Equipment (BAFE)  can advise on companies approved to undertake this kind of survey.

All extinguishers capable of extinguishing class A, B or F fires will carry a fire rating which takes the form of a number followed by a letter (eg. 55B). The larger the number, the bigger the fire the extinguisher can extinguish (under test conditions). The letter will correspond with the classifications above. BS EN 3-7 provides a fuller explanation of these ratings.

Extinguishers should be sited on escape routes on all floors in a place where they can be easily accessed and seen - near a door leading to a place of safety or close to a particular fire risk (within 30m for Class A or C, within 10m for Class B or F) would be ideal. The method of operation for all extinguishers should be identical to prevent confusion where possible and all must be properly labelled. The units should have suitable jet or spray nozzles appropriate to the risk likely to be encountered.
Additional advice can be found in BS 5306- Part 8 .

In a domestic environment a fire blanket and small wet chemical or dry water mist extinguisher would likely be considered satisfactory for most situations in the kitchen. A dry water mist extinguisher would be suitable for the rest of the house.

What should I look for when purchasing fire extinguishers?

BS 6306-0:2011 provides guidance on the application of portable fire extinguishers. You should ensure that all extinguishers you buy meet the requirements of the appropriate British Standard and display the kitemark , Loss Prevention Certification Board (LPCB) mark or Apragaz certification mark. The BAFE mark is voluntary but offers additional assurance of quality.

Your local fire brigade is able to provide expert advice free of charge and will be please to advise on equipment and general fire safety advice. The Chief Fire Officers Association sell a range of products and services via the Blue Watch website online.

How often should I inspect and maintain fire extinguishers?

Extinguishers in commercial or public settings should be inspected each month for damage and serviced in accordance with BS 5306-3 annually by a company registered by the BAFE.

Most manufacturers recommend that water, foam and powder extinguishers should be discharged and refilled every five years and CO₂ gas extinguishers refurbished every 10.

‘Self-maintenance ‘ extinguishers kitemarked P50 require a monthly visual inspection and a yearly visual inspection to be recorded and should be refurbished after ten years. The visual inspection consists of checking the pressure gauges, checking the extinguisher for damage and checking the manufacture date of the extinguisher and recording the result in a fire safety logbook and on the extinguisher.

Any extinguisher once used (even if only partially) must be recharged according to manufacturer guidance.

More details on maintenance and inspection can be found in BS 5306-9: 2015 .

When should I tackle a fire?

You should only tackle a fire in its very early stages, having immediately raised an alarm.

You should always put your own safety (and other people’s safety) first when deciding whether to tackle the fire of exit the building and, before engaging, you should ensure you have a clear escape route.

If it becomes apparent that the fire cannot be put out (or the extinguisher is depleted) you should vacate the building closing doors behind you as your leave and ensure that the fire brigade has been called.

How are fire extinguishers operated?

Fire extinguishers may differ from brand to brand when it comes to operation. It is therefore important, to avoid potential confusion should a fire break out, to provide units that work in the same kind of way throughout your building(s).

Before attempting to fight any fire you should check that the extinguisher is fully charged (many units feature a dial displaying this information) and that the safety pin (fixed through the operating handle).

While sited a safe distance from the fire you should remove the safety pin, breaking the tamper seal. With your extinguisher correctly aimed you should squeeze the lever slowly to begin discharging the extinguisher.

Where should I aim the extinguisher for best effect?

Water Fire Extinguishers

Fire spreading horizontally - Aim the hose at the base of the fire, moving the jet across the area of the fire.
Fire spreading vertically - Aim the hose at the base of the fire, slowly moving the jet upwards following the direction of the fire.

ABC Powder Fire Extinguishers

Solid materials - Aim the hose at the base of the flames, moving across the area of the fire.
Spilled liquids - Aim the hose at the near edge of the fire and with a rapid sweeping motion drive the fire towards the far edge until all the flames have been extinguished.
Flowing liquid - Direct the hose at the base of the fire and sweep upwards until the flames have been extinguished.

Foam Fire Extinguishers

Electrical equipment - Switch the power off if safe to do so and direct the hose straight at the fire.
Flammable liquids - Aim the hose at a vertical surface near the fire, do not spray directly at the fire as this could push the fire causing it to spread to surrounding areas. You need to smother the fire with a build up of foam.
Solid combustibles - Aim the hose at the base of the fire, moving across the area of the fire.

CO2 Fire Extinguishers

Flammable liquids - AIm the horn at the base of the fire and move across the area.
Electrical equipment - Swithc off the power if safe to do so and direct the hose straight at the fire

Wet Chemical Extinguishers

Hold at arm's length well above the fire with its nozzle at least a metre away. Apply the spray in slow circular movements allowing the wet chemical agent to fall gently onto the surface of the fire and avoiding hot oils being splashed onto the user.

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