Foam fire extinguishers: why they deliver concentrated fire-fighting power

Foam fire-fighting technology is now an effective and versatile option for use for a multitude of applications in your home and workplace. We explain why.

When Flight 609 failed to take off from Munich Airport almost 60 years ago this February 6th it ploughed into a house, ultimately killing 23 of its passengers.
But that was only half of the people aboard. All might have died if a fire beneath the starboard wing had reached about 500 gallons of aviation fuel inside it.

This was the flight in which so many of the Busby Babes of Manchester United were killed, and the flames under the wing which might ultimately have killed them all were fought by the aircraft’s pilot, using just two hand-held fire extinguishers.

This incident highlights the way fire-fighting techniques have developed over the years, as part of on-going efforts to make flying safer. In 1959, the year after the Munich disaster, there were 15 accidents per million flight hours. In 2000, that figure had been reduced to just two. That doesn’t mean the problem has been cured, however; according to European flight safety initiative AircraftFire and the FAA, over the last decade there have been 3,000 fire incidents on aircraft, 40 of which involved fatalities.

The fire-fighting contribution to that reduction is, in part, down to the development of Foam Fire Extinguishers – or AFFF – technology.

The use of foam fire extinguishers has grown, since the technology is now available to much smaller users like you and I.

How does a foam fire extinguisher work?

It is extremely effective because of the clever way the ingredients in a foam fire extinguisher work together. These are concentrated foam solution, water and inert nitrogen, which pressurises the extinguisher. When the extinguisher is used, the stored pressure drives out the foam solution, which swirls around in the nozzle, producing a fine spray of foam in a much larger volume than the extinguisher itself.

How does it work? In two ways. The foam seals the fire from its oxygen supply, and secondly the moist foam cools the burning material.
The foam extinguisher colour is usually red with a cream label saying ‘foam’, which conform to British Standard EN3. Stainless steel extinguishers are available for use in design-led or clean environments – but they will still have that cream label. Beware: older foam fire extinguishers aren’t red, but are completely cream. These don’t conform to the EN3 standard, and ought to be replaced and disposed of in an environmentally-friendly way. Your fire extinguisher supplier should be able to do that for you.

Foam fire extinguisher facts

Also called AFFF extinguishers, which stands for Aqueous Film Forming Foam
• Foam fire extinguishers work by building a non-combustible chemical ‘seal’ that cuts off a fire’s oxygen supply
• Much more effective than water alone
• Lighter than the equivalent water extinguisher
• Available in stainless steel for design or hygiene-led locations
• Not recommended for use close to live electrical appliances, because they contain a quantity of water

Foam fire extinguisher uses

What is a foam fire extinguisher used for? Fighting fires of Class A (solids such as wood or paper) and Class B (flammable liquids) at locations including:

• aircraft
• oil refineries
• garages
• forecourts
• workshops
• small industrial locations
• motorsport
• boating
• caravanning

How to use a foam fire extinguisher

• DO spray just above the surface of the fire to allow foam to build up and flow over the fire
• DO spray towards the back of a container containing burning liquid or against a vertical surface behind it
• DO use a gentle side-to-side sweeping motion to cover the whole fire
• DO NOT approach the fire too closely
• DO NOT spray directly onto burning liquid. This pushes the foam beneath the liquid, where it can’t put out the fire, but could spread it to a wider area

If you’re confused about which fire extinguisher is right for your application, our handy guide on the different types of fire extinguishers will help you decide.