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What Fire Extinguisher Should I Use?

We don't sell, service or maintain fire extinguishers.  We only advice on what's best via a Fire Risk Assessment.  So please take this as simple, impartial advice.

What Fire Extinguisher Should I Have?

That depends on the types of fire either you're expecting, the amount you have to spend, people who might have to use the fire extinguisher and what you have already.  We'll go through the types of extinguishers and what fires they work best with.  If a room could have different types of fires (e.g. kitchen) then having multiple extinguishers is a highly recommended.  Especially having a CO2 for electrical fires or Wet Chemical cooking oil fires.  Finally it's worth pointing out that its not advisable to use an extinguisher unless you've had Fire Safety Training.

Fire Extinguisher Types

Water Additive Fire Extinguisher - Like a normal water extinguisher but is mixed with an additive that makes it 'wet' the fire better.  Meaning it soaks in faster and cools the fire quicker.

Water Mist Fire Extinguisher - Instead of an additive this one instead sprays the water in microscopic droplets.  Not only does this put the fire out quicker, as it quickly cools the fire itself.  It also means that it can be used on office/home type electrical fires.  Since the droplets don't allow the electricity to track back up through the mist and then the person operating the extinguisher.  They work well on flammable gases as its a mist and not a stream of water.  Also can be used on flammable liquids as it doesn't penetrate the liquid.  This is important because this can flash-boil the water and the resultant stream will throw burning oil all over the room.

Water Fire Extinguisher - Good old fashioned water, which has served us well.  But offers no advantage over the above 2 other than being slightly cheaper.

Foam Fire Extinguisher - Foam extinguishers create a barrier between the fuel and the oxygen in the air, smothering the fire and preventing its spread.  It works on liquids by floating on top of the liquid, cooling it and removing its access to oxygen.  They are the best for liquids, but not ideal for other types of fire.

Wet Chemical Fire Extinguisher - A wet chemical fire extinguisher is specifically designed to tackle fires involving cooking oils and fats, which are classified as Class F fires. These types of fires are commonly found in commercial kitchens, catering establishments, or any cooking environment where hot oils and fats are used.  When a wet chemical extinguisher is discharged, it releases a solution that combines with the burning oil or fat to create a soapy layer on the surface. This layer acts as a barrier, preventing the fire from getting the oxygen it needs to continue burning. It also cools the fire, reducing the temperature and preventing re-ignition.

Dry Powder Fire Extinguisher - Dry powder extinguishers work by smothering the fire, interrupting the chemical reaction of the fire triangle.  They are good in that they are designed to work on all fire types except burning oils.  But in an enclosed space they can quickly cause visibility issues and create an almighty mess!

All-Fires Fire Extinguisher - As its names suggest its good for all fire types.  The most expensive type, but it might mean that you need just one type in a room rather than two.

CO2 Fire Extinguisher - As you're aware, fires need oxygen to start and grow.  CO2 works by displacing the oxygen, cutting off the fire's oxygen supply.  A CO2 fire extinguisher is preferred on electrical fires for two reasons.  Firstly most electrical equipment is encased in either a plastic or metal box with ventilation slots.  So trying to get a powder or foam inside through tiny ventilation holes is going to be difficult.  CO2 being just a gas with no solids doesn't have this issue. Secondly CO2 causes no mess, it simply evaporates and mixes into the air the room.  Which means that if the device is important or expensive (e.g. PC or laptop) then it may repairable later.  Not so much if its coated in foam or power.

Fire Types

Class A Fire - (Solid combustibles) - This is the most common fire your going to come across, where you have solid objects on fire.  Anything from a rubbish bin on fire to burning pallets or a waste paper bin.  Paper, wood, textiles, furniture etc.

Electrical Fire - (Anything plugged into mains electricity) - The second most common you're going to see  The initial issue is often not that the thing is on fire, but that its still live at 230+ volts.  Which can be deadly.  So you have to chose an extinguisher that does not conduct electricity as well as puts the fire out.  If you were to use a standard water extinguisher on an electrical fire, the stream of water from you to the fire will act like an electrical cable.  Meaning the electricity is now going through you!  The only good thing (if you can say such a thing) about electrical fires is that most electrical devices are made using inflammable materials.  The plastics they are made with are often treated with a chemical that makes them really hard to actually set on fire.  So often electrical appliances are reasonably easy to extinguish with the right extinguisher.

Class B Fire - (Flammable Liquids) - Think of things like petrol, diesel, paraffin, cleaning solvents, even large amounts of hand sanitiser.  Not only can these liquids burn in their own right.  But being they can spread quickly and even soak into things, or drip through floors in a building.  Class B fires can be particularly dangerous because they can spread rapidly and ignite easily.

Class C Fire - (Flammable Gases) -A Class C fire involving flammable gases is a specific type of fire that occurs when gases such as propane, butane, methane, natural gas, and hydrogen ignite. These fires are dangerous due to the potential for rapid spread and the risk of explosion. Class C fires involving flammable gases require special handling and extinguishing agents to safely and effectively put them out.  Also if the gas is contained with a gas bottle then you also have the risk of these exploding.  Often not from the fire getting inside the bottle - there is no oxygen in there so it can't burn.  But instead the fire heating up the bottle, making the gas expand and its pressure increasing beyond what the bottle was designed to hold.

Class D Fire - (Flammable Metals) - Fires involving combustible metals are rare but extremely hazardous due to the intense heat and potential for explosions. It's crucial to use the correct extinguishing agents, such as Class D dry powder extinguishers or sand, and to follow proper safety procedures when dealing with these fires.  Extinguishing a Class D fire involving combustible metals requires specialised extinguishing agents that can effectively smother the fire without reacting violently with the metal. Water and traditional extinguishing agents can actually worsen the situation by causing the metal to react violently.

Class F Fire - (Cooking Oils) - These are fires fuelled by cooking oils and fats, typically found in commercial kitchens, restaurants, and other food preparation areas. These fires are unique because of the nature of the fuel involved, which can make them difficult to extinguish with traditional methods. Class F fires require specialised extinguishing agents designed to handle the specific characteristics of cooking oils and fats.

Lithium-Ion (Li-Ion) Batteries - These seem to be treated as a very new type of fire.  Despite these batteries being around for over 20 years.  The difference is in the manufacturing.  Initially they were only used in fairly expensive devices like laptops and mobile phones.  As such their cost was a small percentage of the overall device cost.  So the manufacturers could afford to add in lots of safety features to protect against things like over heating, over charging, short circuits, physical damage, penetration, dielectric breakdown etc.  Back-in-the-day an average laptop battery would set you back around £150.  Cut to today and the most common Li-Ion pencil battery (18650 3.7V) can be bought for as little as £1.00 each.  To get to that price, a lot of those safety features have been removed.  Which is why you often seen cheap devices like electric scooters bursting into flames, as they contain dozens of these Li-Ion pencil batteries. 

Li-Ion fires are almost impossible to put out.  The fire starts usually starts when a single pencil battery fails.  It then starts to heat up as the Lithium inside reacts with the air.  This heat is then transferred to the other batteries surrounding it, causing them to also degrade and also heat up.  At some point the container that these batteries are in will fail and smoke and later flames will shoot out.  But because its a type of chemical fire, most extinguishers will not have any affect.  CO2, powder and foam extinguishers have little to no affect because the battery fire doesn't need oxygen and can generate its own heat.  Water  works to some extent to cool the battery pack, and is safe because for most portable devices the voltage is typically less than about 30V.  But often the best cause of action is to grab a fire blanket and try to stop the fire spreading to the surround area and items.

What do Fire Extinguishers typically cost?

We've take the liberty of doing this research for you.  The results below are quite startling.

  1. The foam, dry powder and 3 water extinguishers are all more or less the same price (£28-£36 each).  So the Water Mist is a very good all rounder to cover off the 5 most common fire types.
  2. The All Fires is the 3rd most expensive.  But it covers all 6 fire types.  So one of these in a room is cheaper than 2 separate ones.
  3. The Wet Chemical is a lot more than the All Fires Extinguisher, yet only tackles one fire type rather than all 6.
  4. CO2 is also expensive.  But has some advantages on electrical fires so might be worth having in a room full of computers.

Online Extinguisher Prices (As of Q1 2024) inc VAT

  • Water Additive Fire Extinguisher (3 litre £28, 6 litre £36)
  • Water Mist Fire Extinguisher (6 litre £32)
  • Water Fire Extinguisher (3 litre £28)
  • Foam Fire Extinguisher (3 litre £29, 6 litre £31)
  • Wet Chemical Fire Extinguisher (3 litre £56, 6 litre £82)
  • Dry Powder Fire Extinguisher (3 kg £22, 6 kg £32)
  • All Fires Extinguisher (2 litre £29, 6 litre £52)
  • CO2 Fire Extinguisher (2kg £27, 5kg £56)

We hope you liked this article.  If your interested in talking about how we might be able to help you with your Fire Safety them please contact us.  Or if you're just interested in learning a little more about Fire Safety then check our other articles:

Duties of the Responsible Person

Fire Safety Training

Does my business need a Fire Risk Assessment?

What does a Fire Risk Assessment cost?

Personal Emergency Evacuation Plans (PEEP)

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