Class B Foam Concentrates
Class B foam concentrates are designed to extinguish class B flammable liquids. There are two types of class B flammable liquids. The first type is a non-polar flammable liquid which is immiscible in water. Non-polar flammable liquids include gasoline, heptane and crude oil. The second type of flammable liquid is a polar flammable liquid which is miscible in water. Polar solvent liquids include isopropanol, methyl ethyl ketone (MEK) and methyl tertiary butyl ether (MTBE). Generally all foams are designed to be used on non-polar solvents but only polar solvent or alcohol resistant concentrates are effective on polar solvents.
Standard AFFF (Aqueous Film–Forming Foam)
Standard AFFF (Aqueous Film-Forming Foam) is typically available in 1%, 3% and 6% nominal concentrations. AFFF concentrate is a synthetic foam made with fluorinated surfactants and can produce an air-excluding foam blanket. In addition, AFFF foam solutions provide a vapor sealing film on non-polar flammable liquids. Alcohol resistant AFFFs are essentially AFFFs with the addition of polysaccharide polymer. Polar solvents will destroy standard AFFFs but the polymer in AR-AFFFs forms a membrane to separate the polar solvent from the foam blanket.
Alcohol resistant AFFF
Alcohol resistant AFFF is typically available as follows:
- 3/6% AR-AFFF for use at 3% on non-polar solvents and 6% on polar solvents
- 3/3% AR-AFFF for use at 3% on both non-polar and polar solvents
- 1/3% AR-AFFF for use at 1% on non-polar solvents and 3% on polar solvents.
Fluoroprotein foam is typically available in 3% and 6% nominal concentrations. Fluoroprotein foams use protein and fluorochemical surfactants.
Protein foams were the first type of mechanical foams used to fight flammable liquid fires. They are made from the hydrolysis of granulized keratin protein. They also contain additives to prevent bacterial decomposition and corrosion.
FFFP (Film Forming Fluoroprotein Foam)
FFFP (Film Forming Fluoroprotein Foam) is typically available in 3% and 6% nominal concentrations. FFFPs use protein and fluorochemical surfactants; however the fluorochemical surfactants are generally used at a higher concentration than standard fluoroprotein foam, giving these solutions the ability to form a vapor sealing film on non-polar solvents in a way similar to AFFFs.
Alcohol Resistant FFFP
Alcohol resistant FFFPs are essentially FFFPs with the addition of polysaccharide polymer. Polar solvents will destroy standard FFFPs but the polymer in AR-FFFPs forms a membrane to separate the polar solvent from the foam blanket. Alcohol resistant FFFPs are typically available as follows: 3/6% AR-AFFF for use at 3% on non-polar solvents and 6% on polar solvents 3/3% AR-AFFF for use at 3% on both non-polar and polar solvents￼
High Expansion Foam Concentrate
High expansion foam concentrate is a mixture of surface-active agents and synthetic foaming agents. This foam solution must be applied with high expansion foam generating equipment, which produces a foam with an expansion ratio of approximately 500 to 1. High expansion foam extinguishes a fire by cooling the fire and excluding oxygen from the fire. High expansion foam can be used on class A, non-polar class B and polar Class B fires.
￼Class A Foam Concentrate
Class A foam concentrates are typically used at concentrations from 0.1% to 1% in water. By adding class A foam concentrate to water, the resulting foam spreads over the class A fuel and slowly releases water to cool the fire. The foam concentrate also reduces the surface tension of the water enabling it to better penetrate the fuel.