Foam Tender – this is one of the more unusual apparatus operated by the Los Angeles Fire Department. Using a specialized foam (see below) combined with water, this rig is extremely useful when suppressing fires that are resistant to traditional water-based operations.
Class A foams were developed in mid 1980s and were used when suppressing wildfires. Class A foams lower the surface tension of the water which assists in the wetting and saturation of Class A fuels with water. This aids fire suppression and can prevent reignition. Favorable experiences led to its acceptance for fighting other types of fires, including those that occur in vehicles and structures.
Class B foams are for more dangerous fires, where the application of a Class A foam might trigger an unexpected result. Specifically, Class B foams are designed for flammable liquid fires, such as gasoline or jet fuel. Class A foams are not designed to contain the explosive vapors produced by flammable liquids. Class B foams have two major subtypes: Synthetic foams or Protein foams.