What is a firefighting foam?
Firefighting foam is simply a stable mass of small air-filled bubbles, which have a lower density than oil, gasoline, or water.
Foam is made up of three ingredients: water, foam concentrate, and air.
When mixed in the correct proportions, these three ingredients form a homogeneous foam blanket.
How does the firefighting foam work?
Foam is designed for extinguishing fires by smothering and cooling by reducing to zero any risk of restarting the flames.
Like water, foam insulates fuels from the air, separates the oxygen element from the other elements, also retaining flammable vapors.
It forms a stable foam blanket that spreads above the fuels and adheres to surfaces.
Foam fire extinguishers extinguish the fire by taking away the heating element of the fire triangle, and by sealing the surface of the liquid.
When the firefighting foam can be used?
Foam fire extinguishers can be used on Class A and B fires:
Class A – fires involving solid materials such as wood, paper, or textiles.
Class B – fires involving flammable liquids such as petrol, diesel, or oils.
They are most suited to extinguishing liquid fires such as petrol or diesel and are more versatile than water jet extinguishers because they can also be used on solids such as wood and paper.
They are not suitable for use on free-flowing liquid fires.