What is Fire Fighting Foam?
Foam is a dense composition of air-filled bubbles. Foam consists of three components: Foam, Water and Air. Foam solution is obtained by mixing the proportioned water with the foam concentrate. Mixing of the foam solution with air is achieved by passing it through foaming devices.
The first use of foams in flammable liquid fires in the world dates back to the 1900s. In these years, mechanical foams were not invented yet, and only chemical foams obtained from the reaction of sodium bicarbonate and aluminum sulfate with the foaming agents of CO2 gas were used. Mechanical foams have been invented since the 1930s. Synthetic foaming agents have started to be used with foaming devices at a certain rate.
Expansion Rate (Expansion)
The expansion ratio is equivalent to the ratio of foam solution to expanded foam. There are 3 types of expansion.
When foams are grouped according to their chemical component and characteristic performance, they can be examined in 7 main types.
1- Protein Foam Concentrate ( P )
It is a type of foam obtained by hydrolyzing animal nail horns with various metallic salts and additives. It is used against hydrocarbon fires. They are usually produced at a rate of 3% and 6%.
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2- Fluoroprotein Foam Concentrate ( FP )
It is a type of foam obtained by extracting fluoroprotein surfactants into protein foam concentrates.
In addition to the properties of protein foams, faster flow on the fuel surface, suppression force and extinguishing ability are its advantages over protein foams.
3- FFFP (Film Forming Fluoroproteins)
It is a type of foam formed as a result of the combination of protein foam and film-forming surfactants and stabilizers.
It effectively forms a film on the surface of highly flammable and combustible hydrocarbons. This film suppresses flammable vapors like AFFF. Compared to fluoroprotein, it has a faster suppression effect and stability. It is used at rates of 3% and 6%. They can expand up to 10:1 ratio in low expansion lances and 50:1 ratio in medium expansion lances. At the same time, FFFPs can be used with very low expansion lances.
Standard film-forming foam concentrates cannot be used on polar solvent fires.
4- AFFF (Film Forming Foam Concentrate)
Aqueous film-forming foams are the type of foam that is formed as a result of combining fluorochemical surfactants and synthetic foamers, and is suitable for use with fresh water and sea water.
The film layer formed by AFFF spreads rapidly on the surfaces of hydrocarbon fuels, effectively extinguishing the fire, cooling and forming a cover to pass the flammable vapors. Even if the film layer spread on the fuel surface is somehow dispersed, it regains its original form.
The main areas of use of AFFF foams are in oil refineries, fuel tankers, fuel storage facilities, and can also be used against Class A fires as it is a useful wetting agent thanks to its low surface tension. It can be applied with low, medium and very low expansion lances.
Not effective on polar solvent fires.
5- Synthetic Foam Concentrates
Synthetic foam is a type of foam formed as a result of the combination of synthetic-based foamers and stabilizers. It is used as medium and high expansion. It has good fluidity and suppression ability. Short drainage time and late fuel coating level are disadvantages.
Therefore, it is not preferred in fuel fires.
However, it provides maximum protection in large areas. It is especially recommended for use in warehouses, hangars, machine rooms, ship decks, mines and basements.
It can be foamed at a rate of 1000:1 with high-expansion generators.
1.5% 2%, 3% and 6% types are available.
6- Ar Type Foam Concentrates
Polar solvents, i.e. water-miscible fuels, destroy the foam layer formed by the foams used to extinguish hydrocarbon fires.
The foam type known as ‘Alcohol resistant’ is used in this type of fuel. It is generally produced on the basis of AFFF and FFFP. They form multi-purpose foam concentrates by applying them to both hydrocarbon and polar solvent fires with 2 types of correct application techniques.
The polymeric additive in AR type foams adheres to the structure of the foam until it mixes with the polar solvent. The polymeric membrane contained in the foam colliding with the polar solvent provides quenching by knitting a polymeryl film layer on the surface. In addition to the AFFF and FFFP properties, the high stability and flame retardancy level is provided by the polymer additive.
Scope of Application