How to Use a Fire Extinguisher

Everyone has seen fire extinguishers used in films and tv shows but very few people actually know how to use a fire extinguisher properly in an emergency and when it’s appropriate.

The most important thing during a fire is your safety, so knowing what to look out for and how to judge when you should attempt to fight the fire or not is crucial.

What to Do If There’s a Fire

If you come across a fire, you should warn people nearby and trigger the alarm before you even think about getting a fire extinguisher. If you aren’t fighting the fire, then immediately exit the building using the stairs (not a lift) and if the room is filling with smoke then either find another route or crawl along the floor to avoid smoke inhalation.

When to Use a Fire Extinguisher

When the alarm has been sounded and you are sure of your escape route then, and only then, consider using a fire extinguisher. If the fire is still small and confined to only one or two objects, if the air is safe to breathe, and if there is only a slight increase in heat on approach then the fire may be small enough to be put out with a portable extinguisher.

Remember to be continually aware of smoke danger and your escape route. If it looks like you’re going to be put in danger then leave immediately and wait for help.

How to Properly Put Out Fires with an Extinguisher

First, make sure again that your evacuation route is clear, and check that your fire extinguisher is suitable for the type of fire (this is especially important for deep fat fryer fires and electrical) by reading the information on the front. Also check that the pressure gauge is within the green range. If everything looks good, then you are ready to approach the fire – be sure to stay at least 1 meter back at all times.

When using a fire extinguisher, you should remember the mnemonic ‘PASS’. First is P – pull the pin and break the anti-tamper seal, then A – aim the nozzle at the base of the fire, S – squeeze the lever to activate the extinguisher, and finally S – sweep from side to side until the fire is out or the extinguisher is empty.

After you have extinguished the fire, back away immediately in case the fire flares up again. If the extinguisher is empty and the fire is not extinguished then you should evacuate immediately, taking the empty fire extinguisher with you if possible.

Fire Extinguisher Types

Different types of fire extinguishers can be used to combat different types of fire. Take your time when considering what fire extinguisher to purchase and, in an emergency, make sure that the fire extinguisher you have is appropriate for the fire.

Water Fire Extinguishers

Water fire extinguishers should only be used on freely burning materials, i.e. fires that are made of burning wood, plastics, coal, or soft furnishings. Water spray extinguishers are a more effective variant that creates a fine mist and often contains surfactants to help the water penetrate burning materials.

Make sure you do not use these extinguishers on electrical fires – as they can conduct electricity through the stream – or deep fat fryer fires as they will vaporise violently into steam, spreading the burning oil further.

Foam Fire Extinguishers

Foam fire extinguishers are best used on burning liquids, such as paint and petrol, as the foam can float on the liquid surface and cut the fire off from its fuel. However, these are not suitable for use on cooking fires. These also work well on freely burning materials (wood, furnishings etc.) and some varieties are safe for use on electrical fires, although will cause considerable additional damage to electrical equipment.

Foam extinguishers create an effective layer when used which makes them very useful at preventing re-ignition.

CO2 Fire Extinguishers

CO2 fire extinguishers are excellent for combating electrical fires and fighting flammable liquid fires. However, they are ineffective when used on wood and textile fires, flammable gasses, and cooking fires. Do not use this type of fire extinguisher on a deep fat fryer fire as it can blow burning liquid across the room, spreading the fire.

CO2 fire extinguishers can also be the most dangerous to operate as the nozzle becomes extremely cold when used, causing severe frost burns if held with bare hands. You should always operate a CO2 extinguisher by holding it behind the nozzle. CO2 can also cause asphyxiation if there is no ventilation, so after an extinguisher is used you should evacuate the room to ensure your safety.

Powder Fire Extinguishers

Powder fire extinguishers can be used on freely burning materials (wood, plastic, coal etc.), burning liquids such as grease paint or petrol, and electrical fires. These are also the current go-to solution for gas fires. These extinguishers are not suitable to combat chip or fat pan fires.

This type of fire extinguisher is well-suited to the rapid knockdown of fires but, as this powder is less effective at cooling, it may not keep the fire supressed. They also carry the risk of powder inhalation which can be harmful. These models are no longer recommended for domestic use for this reason.

Wet Chemical Fire Extinguishers

Designed for kitchen fires involving burning oil and deep fat fryers, chemical fire extinguishers are great for kitchen fires as well as use on freely burning materials such as wood, textiles coal etc. This type of extinguisher works using a fine spray to cool the fire while the chemical component creates a surface on the burning oil to cut off the fuel source.

Dry Water Mist Fire Extinguishers

Dry water mist fire extinguishers are incredibly versatile and can be used on cooking fires and freely burning materials as well as fires caused by flammable liquids, flammable gases, and electrical appliances. The only type of fire they cannot be used on is flammable metal fires as these tend to chemically react with water.

As this is made from pure water, there are no inhalation risks involved and no issues with chemicals during clean-up. As the water is de-ionised, it’s no longer electrically conductive. Plus, due to the mist being incredibly fine, it can be used on burning deep fat fryers without the water vaporising violently which stops the fire from spreading further unlike traditional water extinguishers.

What To do With Empty Fire Extinguishers

If you’ve used a fire extinguisher and you need to evacuate the building, you should take the used extinguisher with you – if possible – so that no-one attempts to use an empty extinguisher during their own evacuation.

Once a fire extinguisher has been used, even if only for a tiny amount of time, you must either recharge or replace the extinguisher. This is because the pressure seals may have been compromised and it may leak pressure, causing it to become ineffective. As long as your fire extinguisher is not a disposable one and is up to current safety standards, it should be suitable for refilling after it has been discharged.

As fire extinguishers are often classified as hazardous waste, if you want to dispose of one then you should take it to your local manned refuse and recycling centre who it will be taken care of. Under no circumstances should you simply throw one into a bin.

We hope you’ve found this article useful and that you’re now familiar with the types of fire extinguishers available. If you’re interested in learning more about fire safety, why not check out our handy guide on how to fit a smoke alarm?