Foam Spray Fire Extinguishers

ADVANTAGES

ü       Smaller Extinguisher – The foam extinguishers are a lot smaller than their standard water equivalents but carry the same Class A Fire rating. Typically a 3Litre Foam will weigh 70% less than a 9Litre water but both have a 13A rating.

ü       Multiple Classes Of Fire Covered - Can be used on both Class A and Class B fires, also if used inadvertently on a fire involving electrics (up to 35Kv) the operator will not get a electric shock.

ü      Quick Knock Down – The AFFF extinguisher medium gives a rapid knockdown of the fire and in the case of contained flammable liquid fires the fuel is covered by a film of foam that help cool the fuel as well as sealing in the flammable vapours.

ü      Visibility - Does not impair visibility of the operator when used.

ü       Suitability – The foam extinguisher is non-toxic and non-damaging to most materials.  That said the environmental implications of using foam extinguishers should always be considered.  Effective against obstructed Class B fires such as car engine bays.  Can be applied to liquids in tanks shielding them from another source of ignition.

DISADVANTAGES

X        Freezing Problems – Due to the extinguisher being mainly water, the extinguisher is liable to freezing, even with a Low freeze additive added it will only be suitable in temperatures down to minus 10^oc.

X        Flammable Liquid Fires - Although foam can be used on most flammable liquid fires, there are limitations to the liquids covered.  Consulting with the datasheet of the liquids to be covered will help identify which foam should be used, fires involving alcohol require alcohol-resistant aqueous film forming foam (AR-AFFF).

X       Costs – The cost of purchasing and refilling are higher than the water extinguishers and with the additional environmental implications of disposing of foam will see higher recharging costs.

Foam extinguishes Class A Fires by cooling the burning material and removing the heat from the combustion triangle.