Foam

Question 1

What is foam?

Answer 1

Chemical & Mechanical (Air) Foam consists of a cohesive mass of fine bubbles, which must be relatively heat-resistant and long-lasting to be effective; it must be delivered to the fire faster than it can breakdown from the fire exposure; it must have a lower density than the flammable liquid to make it float on the surface; it must have a low enough viscosity to spread and flow over liquid surfaces, around obstructions and form a complete seal over the entire surface. The characteristics must be evident whether the foam is produced chemically or mechanically. Foam is employed primarily for the extinguishment of flammable liquid fires. It extinguishes by blanketing the liquid surface; obstructing access of the flammable vapours to the air; insulating the flammable liquid from the heat of the fire and cooling the surface.In general foam works by forming a blanket of foam on the burning fuel. THe foam blanket excludes the oxygen and stops the burning process. The water in the foam is slowly released as the foam breaks down. This action provides a cooling effect on the fuel.

Question 2

What types of foam are there?

Answer 2

Type A
Type B

Question 3

What is type A foam used for?

Answer 3

ordinary combustibles

Question 4

What is type B foam used for?

Answer 4

flammable and combustible liquids. Think of B = Barrel

Question 5

How is type A foam formulated?

Answer 5

mixing 0.1% - 1.0% concentrate with 999 gallons of water (makes 0.1% concentrated foam) or with 99 gallons of water (makes 1.0% concentrated foam)

Question 6

How is type B foam formulated?

Answer 6

3% (3 gallons of concentrate) with 97 gallons of water
6% (6 gallons of concentrate) with 94 gallons of water