Foam Fire Extinguishers

Foam fire extinguishers have come a long way in 30 years. The original foam was thick, gloopy and smelled appalling, due to its high animal protein content. (Not good for vegetarians, then!)

Modern Aqueous Film Forming Foam (AFFF) fire extinguishers are another breed altogether, one of the best all-round units available. Foam extinguishers are red with a cream panel above the operating instructions.

How Aqueous Film Forming Foam (AFFF) Fire Extinguishers Work

When sprayed onto a fire, AFFF foam (pronounced A-triple-F) extinguishes and smothers the flames, then seals in any harmful vapours under the outer film of foam.


The foam also penetrates absorbent materials, and cools the fire as the water in the foam evaporates.

Foam is extremely effective on Class A fires, involving paper, wood, etc, so they are a good choice for a general office fire extinguisher are particularly great on man-made furnishings, where the fibres in the fabrics might otherwise liquify in the heat of the fire.

When used on flammable liquid fires (Class B), the foam forms a film that prevents re-ignition of the flammable liquids by sealing the liquids away from oxygen in the air.

Light in Weight but Not Lightweight

AFFF extinguishers are lighter than ordinary water ones because the 6 litre foam has the same 13A fire rating as the heavier 9kg water only equivalent.

Foam Fire Extinguishers and Electricity

The foam spray nozzle that sprays the foam evenly, allowing you to coat the fire area quickly. Since the foam fire nozzle is non-conductive, you can use an AFFF fire extinguisher near (but not directly on) live electrical equipment. The quality models will have been tested to the BS EN3 35,000V dielectric test as defined by BSEN3-7:2004.

Foam Fire Extinguishers Containing PFOS

Perflourooctane Sulphonate (or PFOS) was used for many years in foam extinguishant. However, it has been proved to be toxic and a potential risk to aquatic wildlife, in addition to having a known carcinogenic content. Major manufacturers UK of extinguishers such as Chubb and Thomas Glover have not used PFOS in their foam fire extinguishers since 2001.

3m’s Lightwater was the world’s most popular fire fighting foam but production was stopped long ago.

Chrome Aqueous Film Forming Foam Fire Extinguishers

AFFF fire extinguishers are also available in chrome, for when “red will so clash with the decor, darling!” Chrome finish fire extinguishers of any type are not BS EN3 certificated, as they are not painted red.

However, from the quality manufacturers such as Chubb Fire, Thomas Glover and Amerex, they still feature all the required safety instructions, and CE mark and use the same components as their red versions.