Fire Suppression

Fire fighting foam is to cool the fire and to coat the fuel, preventing its contact with oxgen, resulting in suppression of the combustion. Low expansion foams have an expansion rate less than 20 times. Low expansion foams such as AFFF are low-viscosity, mobile and able to quickly cover large area. Foams with expansion ratio between 20-200 are medium expansion and high expansion foams have an expansion rate over 200. Alcohol resistant foams contain a polymer that forms a protective layer between the burning surface and the foam, preventing foam breakdown by alcohols in the burning fuel. Class A foams lower the surface tension of the water which assists in the wetting and saturation of Class A fuels with water, aiding fire suppression and prevent reignition. Class B foams are designed for flammable liquids.
 
Every type of foam has its application. High expansion foams are used when an enclosed space, such as a basement or hangar, needs to be quickly filled. Low expansion foams are used on burning spills... etc.  

Various fire fighting foam systems available with UL (Underwriters Laboratories) listing; FM (Factory Mutual) approval; major marine classification type approval