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Foam Fire Extinguishers & How To Use Them 

Learn everything about foam fire extinguishers, from the colour of their label and where to find them to what types of fire they extinguish and how to use them safely in case of a fire incident, in our handy guide to foam fire extinguishers. 

Foam fire extinguishers (also known as AFFF fire extinguishers) are one of the most commonly used fire extinguisher types in the UK. Their popularity is due to the fact they can extinguish fires involving both flammable liquids (petrol, diesel, paint) and combustible organic materials (paper, plastic, woods). In fire safety terminology, these are respectively referred to as Class B and Class A fires. 

As the foam extinguisher is lighter than a water extinguisher of the same size, it’s easier to use which makes it a preferred choice for use on Class A fires. The foam discharged during use is non-toxic and apart from leaving a mess for you to clean, it isn’t likely to cause any damage. It is also designed to prevent reignition once the flames have been put out. 

Foam fire extinguishers are not recommended for use on electrical fires either but if your extinguisher has undergone a 35kv conductivity test (or a BS EN3 35,000V dielectric test), there shouldn’t be any significant problems if it’s accidentally used on an electrical fire. However, foam fire extinguishers should never be used on Class C (flammable gas fires) and Class F fires (cooking fires). 

You’ll usually find foam fire extinguishers in office buildings, hotels, warehouses and other buildings accessible to the public. In an office environment, a foam fire extinguisher can usually be found paired up with a CO2 fire extinguisher as the latter is effective on fires involving electrical equipment. 

How to recognise a foam fire extinguisher

Each fire extinguisher type can be identified by the colour of its label. The label of the foam fire extinguisher is cream.  The label should also have the word “Foam” written across in large capital letters so you won’t have to worry about remembering the fire extinguisher colours in an emergency situation. 

In the UK, the canister of a fire extinguisher is usually bright red. This applies to all types of extinguishers, including AFFF extinguishers. Foam fire extinguishers are also available in silver. Those are referred to as chrome fire extinguishers and they are made of steel. If you come across one of these, don’t worry – they have the exact same functionality as a normal red foam fire extinguisher, only the colour of the canister is different. 

How do foam fire extinguishers work?

Foam fire extinguishers work by combining the power of water with special Aqueous Film Forming Foam (AFFF), which makes them a double-action solution. When you use an AFFF extinguisher it does the following two things:

  • Cools the fire: Due to their water-based properties, foam fire extinguishers attack the heat element of the fire triangle, in the same way that a water fire extinguisher would. 
  • Prevents reignition: The Aqueous Film Forming Foam creates a thin barrier between the flames and the burning surface and smothers the fire, preventing reignition

In the past, foam fire extinguishers also used to contain an active ingredient called Perflourooctane Sulphonate (or PFOS). It was banned in the early 2000s as it was discovered that this chemical was toxic and could be harmful to both humans and the environment with severe negative effects, such as causing cancer and destroying marine wildlife. Modern AFFF extinguishers on the UK market no longer contain PFOS to reduce global pollution. 

How to use a foam fire extinguisher

Before you try to extinguish a fire using any fire extinguisher, including the AFFF type, you should first make sure that you are not in danger. You should always have clear access to an escape route and you should never attempt to take on the fire if the flames are too big or if there is too much smoke. 

Also, if you don’t have the appropriate fire extinguisher training and you don’t feel confident in using the extinguisher, the safest choice is to evacuate the building alongside everyone else and let the firefighters handle the problem.  

If the situation allows you to safely extinguish the fire using a foam fire extinguisher, you should do the following: 

  • Quickly inspect the pressure gauge and the safety pin to see if the extinguisher is full and undamaged 
  • Take a position at a safe distance away from the fire 
  • Break the tamper seal 
  • If it’s a Class A fire (paper, wood, plastic), aim at the base of the fire and sway the hose across the flames
  • If it’s a Class B fire (flammable liquids), aim at a vertical surface close to the flames. Do NOT aim directly at the fire 
  • Squeeze the lever to release the foam
  • Slowly move towards the fire as the flames get smaller

Even though an AFFF extinguisher is designed to prevent reignition, if you have a fire blanket at hand it’s a good idea to cover the area where the fire was burning once it has been extinguished. This provides additional protection against re-ignition. 

We mentioned earlier that if you are dealing with a burning liquid, such as petrol or paint, you should NEVER aim the extinguisher directly at the flames. Doing so could push the fire aside, causing it to spread across the surface. 

After using the foam extinguisher, you will have to clean up the area. This can easily be done by soaking up the water and foam with a towel, followed by thorough washing with water and drying up any excess liquid with a towel once again. Of course, you should always leave the cleaning job after the fire emergency services have cleared the scene and have given you the green light to re-enter the building. 

Foam fire extinguisher legal requirements

According to UK regulations, every building in the UK is required to have at least two Class A fire extinguishers, such as a foam fire extinguisher, on each floor. These must be securely fitted to the wall or stored in special safety cabinets to prevent tampering or damage. 

Every AFFF fire extinguisher must be commissioned by a competent person when it’s installed in the building. This means that it has to be inspected by a trained fire safety engineer to determine that it’s safe to use and that it’s been installed in line with all relevant regulations. 

After that, the foam fire extinguisher will require a regular annual fire extinguisher service by a qualified engineer, along with daily visual inspections by the fire marshal. 

Your foam fire extinguisher has to be replaced every five years from the date of commissioning or six years from the date of manufacture, whichever occurs first. 

AFFF fire extinguisher sizes 

Foam fire extinguishers are commonly sold in a range of sizes, including 2l, 3l, 6l and 9l with 6l being the most popular choice. For high-risk areas, such as petrol stations and large industrial buildings, you may be interested in getting wheeled foam fire extinguishers – they go up to 50l. 

Buy a Foam Fire Extinguisher

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