Foam

Foam is gas bubbles composed from water liquids in different ways. Foam can float on the surface of flammable liquids prevent oxygen and extinguish fire.

Foam basic component: protein produced from vegetable and animal protein like bones and nails besides some chemicals.

Types of foam:

1. Chemical foam: a product of the chemical reaction between aluminum sulfate and sodium bicarbonate.
2. Mechanical foam: it is produced by steering foam solvents in water under exposure of air. There are five types of mechanical foam as follows:

A. Protein foam:

It is composed of natural proteins that are dissolved in water. Some materials are added to protein foam to prevent freezing, decay and to keep the foam in liquid state ready for use.

B. fluoric-protein foam:

This is protein foam with a slight portion of fluorine added to it. It covers the inflaming surface of the oil; insulates air and prevents inflammable vapors coming out of the oil.

C. Light-water foam:

Consisting of Fluorine hydrocarbon dissolved in water besides other anti-freeze chemicals. It is characterized by low viscidity and quick flow; the color is light ranging between transparent and yellow.

D. High-diffusion foam:

It consists mainly of ammonia sulfate salts dissolved in fresh water that is characterized by a large-scale bubble containing inert or inflammable gas. The cover consists of a stable thin wall of water solution.

E. Intensive alcohol-resistant foam:

These materials are made of Fluoric-protein or normal protein materials soluble in water but not in alcohol, that they protect the components of the bubbles form melting, in addition to other foam, materials made from non-natural materials containing jell materials surrounding bubbles shaping a layer on the surface of the liquid to be extinguished.
 

Foam characteristics:

1. Cohesion strength.
2. Adhesion Strength 
3. Free flow.
4. Light weight