Foam fire extinguishers

 

Foam fire extinguishers are one of the most common types of fire extinguisher, and are generally used for fires involving flammable solids and liquids.  We explain all in our simple guide.

Summary:  foam fire extinguishers are good, general use extinguishers, suitable for the majority of premises.


Also known as:

• AFFF foam fire extinguishers
• Spray foam fire extinguishers


Foam fire extinguisher uses:

• Fires involving flammable solids, such as paper, wood, and textiles (‘class A’ fires)
• Fires involving some flammable liquids, such as petrol, diesel, and paint (‘class B’ fires)
• Fires involving electrical appliances IF the extinguisher has passed the 35kv conductivity test

Please note: foam extinguishers are not explicitly designed for use on electrical fires.

The 35kv conductivity test is an additional safety measure intended to safeguard users who accidentally use a foam fire extinguisher on an electrical fire – there is a risk to using a foam fire extinguisher this way, including the possibility of getting an electric shock.

We strongly recommend ONLY using a CO2 extinguisher or a Dry Powder extinguisher for electrical fire risk.


Do not use foam fire extinguishers for:

• Cooking fires involving oil and grease, such as chip pan fires (‘class F’ fires)
• Fires involving flammable gases, like methane and butane (‘class C’ fires)


foam fire extinguishers

How to identify a foam fire extinguisher:

• CREAM coloured label stating ‘Foam’
• Should be identified by an extinguisher ID sign fixed nearby – ‘Foam Extinguisher’


Sizes of foam fire extinguisher available:

• 2 litre
• 3 litre
• 6 litre (most commonly used)
• 9 litre


How foam fire extinguishers work:

Foam fire extinguishers work in 2 ways.

Firstly, they are mainly water-based and so have the same cooling effect as water extinguishers, putting the fire out by lowering the temperature.

Secondly, they contain ‘Aqueous Film Forming Foam’ (this is why they are also known as AFFF foam extinguishers).

AFFF works by smothering the fire and sealing in the flammable vapours. This prevents the fire re-igniting. It also allows foam fire extinguishers to put out flammable liquid fires, by creating a barrier between the liquid’s surface and the flames.


Pros and Cons of foam fire extinguishers:

Pros: non-toxic, non-damaging to most materials, largely safe if accidentally used on electrical fires (although this is not recommended), designed to prevent the re-ignition fires, lighter in weight than the equivalent water extinguisher.

Cons: damaging to electrical appliances. Dangerous if used on cooking fires or flammable gas fires.


Who needs foam fire extinguishers?:

Foam fire extinguishers are the ideal extinguishers for premises with multiple fire risks, such as:
• Offices
• Warehouses
• Factories
• Garages
• Hotels

In fact, most premises benefit from having foam extinguishers and these are frequently recommended, especially when paired with CO2 extinguishers for use on electrical fires.

Read more about the different types of extinguisher here.


How to use a foam fire extinguisher:

foam fire extinguishers how to remove safety pin

Removing a safety pin

Foam fire extinguishers need to be used differently, depending on the type of fire.

In all cases, firstly remove the safety pin to break the anti-tamper seal, and stand well back from the fire.

Flammable liquids fires:

• Do NOT spray directly at the fire, this can cause it to spread to nearby surfaces
• Where the liquid on fire is contained, point the extinguisher at the inside edge of the container
• If it’s not contained, spray with a gentle, sweeping movement across the TOP of the fire, or against an adjacent surface
• This way the foam will drop down and settle on the top of the burning liquid

Flammable solids fires:

• Aim at the base of the fire
• Keep the extinguisher moving forwards and backwards across the flames as you spray

Electrical fires (not recommended):

• Treat the same way as flammable solids fires
• Make sure you are standing at least 1m away from the flames to minimise the risk of electric shocks


If you think you need foam fire extinguishers, or if you’re not exactly sure what you need, just get in touch with our friendly team by calling 0845 845 3001, or emailing info@surreyfire.co.uk.  They can arrange a free survey visit for you from a BAFE registered engineer.

All extinguishers we supply come with a 5 year guarantee, and we will fit and commission them for you, free of charge.

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