How do fire extinguishers work?

For a fire to sustain itself three things are necessary, a
fuel supply, oxygen and a sufficiently high temperature. Fire extinguishers work by
cutting off the supply of oxygen and reducing the temperature. Some fire extinguishers
can also cut the supply of fuel to the fire.

There are many
different types of fire extinguishers each of which is appropriate for a particular type
of fire. Water is extensively used as a fire
extinguisher.

It works by reducing the temperature as the
heat is absorbed by the water and it gets converted to water vapor. Water cannot be used
in cases where electricity is the cause of the fire as water conducts electricity, it
also cannot be used when the fuel can float on water or the fuel reacts with water to
cause an explosion.

In these cases foam based extinguishers
or dry powder extinguishers and carbon dioxide extinguishers can be used. Foam and
powder based extinguishers cut the supply of oxygen to the fuel. These also release
carbon dioxide at high temperatures that works to smother the fire. Carbon dioxide
extinguishers also cut the supply of oxygen with carbon dioxide. Also, as the carbon
dioxide is stored in the extinguisher under very high temperatures, it has a very cold
temperature when it emerges which acts to reduce the temperature below that required to
sustain the fire.