Extinction by smothering, cooling and oxygen starvation

Question 1

Fires can be starved of fuel in

three ways. give examples of each

Answer 1

1. By removing potential fuel from the neighbourhood of the fire. For example, by:
   draining fuel from burning oil tanks;
   working out cargo at a ship fire;
   cutting trenches or creating fire breaks in, for
   example, peat, heath and forest fires,
   demolishing buildings to create a fire stop;
   and counter-burning in forest fires.
2. By removing the fire from the mass of combustible
   material - for instance, pulling apart a
   burning haystack or thatched roof.
3. By dividing the burning material into smaller
   fires which may be left to burn out or which can be
   extinguished more easily by other means. The
   beating out of a heath fire owes much of its effectiveness
   to this.

Question 2

The general procedure of smothering for extinction

give examples

Answer 2

to
try to prevent fresh air from reaching the to the seat
of the fire and so to allow the combustion to reduce
the oxygen content in the confined atmosphere
until it extinguishes itself. This is less effective
where, as in the case of celluloid, the burning
material contains within itself in a chemically
combined form the oxygen it requires for combustion

battening down ships hold
persons clothing alight
sand on metal fire
capping oil well
and FOAM

Question 3

state 3 extinguishing agents that use the principle of smothering

Answer 3

foam
CO2
dry powder (though it inhibits as well)

Question 4

describe the principal of extinguishing by cooling

Answer 4

If the rate at which heat is generated by combustion
is less than the rate at which it is lost from the
burning material, burning will not continue.

So. to extinguish a fire by cooling, the rate at
which heat energy is lost from the burning material
must be increased by removing some of the heat
energy. This reduces the temperature of the burning
mass, reducing the heat release rate.
Eventually, the rate at which heat is lost from the
fire may be greater than the rate of heat production
and the fire will die away.

Question 5

when cooling what visually indicates the severe fire is under control

Answer 5

When the heat of a fire is considerable, as in its
early stages, the steam formed will not be visible,
but as the temperature falls the steam will condense
above the fire. This is widely recognised by
experienced fire-fighters as a sign that a fire is
being brought under control