Explained: Foam type portable fire extinguisher

Foam type portable fire extinguiher

Chemical foam type extinguisher:

A chemical foam type extinguisher contains two containers, the inner and outer container. The inner container contains Aluminium sulphate solution and the main outer container contains soda bicarbonate solution.

To prevent the mixing of both the solution, the top of the inner container has a sealing arrangement.
In case of fire, turn the neck ring to lift the plunger on the gunmetal top cap and unlock the seal. Turn the extinguisher upside down and shake it thoroughly.

This allows the two solutions to chemically mix to produce aluminium hydroxide, sodium sulphate and carbon dioxide (now nitrogen).
Aluminium hydroxide and sodium sulphate combine to produce foam.
Pressurized carbon dioxide gas ( now nitrogen) expels the foam outside the extinguisher through the nozzle, thereby extinguishing the fire.
Chemical foam extinguisher is used to fight class A and Class B fires.

Mechanical Foam Type fire extinguisher:

Mechanical foam type extinguisher consists of a plastic bag filled with foam concentrate fitted below a carbon dioxide (now nitrogen) gas cartridge. The remaining area is filled with water.

In case of fire, hold the hose in the direction of fire, remove the safety guard and press the plunger.
The plunger pierces the cartridge and the carbon dioxide gas (now nitrogen) ruptures the foam bag allowing the foam concentrate to mix with water.

Carbon dioxide (now nitrogen) gas under pressure expels the foam solution out of the branch pipe through the dip tube.
Air enters into the pipe through air intake and generates good quality air foam solution which helps to smother the fire.
This type of extinguisher is used to fight class A and class B fires.

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