Foam Fire Extinguishing System used in fire protection is an aggregate of air-filled bubbles formed from aqueous solutions, and is of lower density than the lightest flammable liquids. It is mainly used to form a coherent floating blanket on flammable and combustible liquids to prevent or extinguish fires by excluding air and cooling the fuel. It then prevents re-ignition by suppressing the formation of flammable vapours, and also adheres to surfaces, providing a degree of exposure protection from adjacent fires.
Foam can be used as a fire prevention, control or extinguishing agent for flammable liquid in tanks or processing areas.
Foam concentrate types
- Protein foam concentrate. It is diluted with water to form 3% to 6% solutions depending on the type and, in general, it is only
- Fluoroprotein foam concentrate is very similar to protein foam concentrates. It may also deposit a vaporisation preventing film on the surface of a liquid fuel. It is diluted with water to form 3% to 6% solutions depending on the type, and is used for crude oil or refined oil products where a higher degree of protection is preferred.
- Special ‘alcohol type’ foam concentrate forms a foam that has an insoluble barrier in the bubble structure which resists break down at the interface of the fuel and foam blanket. It is used for fighting fires in water solution and certain flammable or combustible liquids and solvents that are destructive to regular foam. Mainly used for protection onboard chemical tankers.
- Synthetic foam concentrate includes: AFFF and medium and high expansion foam concentrates are used to produce foam or foam-to-solution volume ratios from 20:1 to approx. 1000:1 and are used for local protection and engine room hi-ex systems.