Fire ventilation
Fire ventilation
Fire ventilation
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esults in quicker and more simple extinguishing. The<br />
spread of the fi re can be more easily prevented and therefore<br />
the damage caused by the fi re can be better contained.<br />
<strong>Fire</strong> <strong>ventilation</strong> at a later stage, when the fi re is <strong>ventilation</strong><br />
controlled, often means that it is more diffi cult to<br />
implement internal suppression. In closed areas the fi re<br />
scenario can accelerate violently when air gains access to<br />
the fi re as a result of fi re <strong>ventilation</strong>, in particular if the fi re<br />
has been underway for a prolonged period in the closed<br />
area. The intensity of the fi re can increase, the fi re spreads<br />
more quickly, more fi re gases is formed, and the fi re becomes<br />
more unpredictable. If the fi re rapidly becomes fully<br />
developed it can be more diffi cult to penetrate into the fi re<br />
room. The impact of the heat increases both on the enclosing<br />
structures and on the fi re fi ghters. There is also an<br />
increase in the production of fi re gases, which can spread<br />
the fi re. <strong>Fire</strong> <strong>ventilation</strong> of areas with fully developed fi res<br />
has a limited effect. It can therefore be wise to vent adjacent<br />
rooms where the damage is not so serious.<br />
<strong>Fire</strong> <strong>ventilation</strong> should be implemented as soon as possible<br />
during the fi re and rescue operation. If the fi re is fully<br />
developed in one or more rooms, it is very often better to<br />
focus on fi re <strong>ventilation</strong> of the adjacent rooms where the<br />
fi re has not yet spread.<br />
Extreme caution is required in the case of <strong>ventilation</strong>controlled<br />
fi res in very large or inaccessible rooms. Above<br />
all it is necessary to coordinate with other measures being<br />
taken at the scene of accident, in particular the suppression<br />
measures. In all probability the fi re will increase in intensity<br />
after implementing fi re <strong>ventilation</strong>. If air is supplied to a<br />
<strong>ventilation</strong>-controlled fi re the worst scenario can be a fi re<br />
gas explosion, or a backdraft.<br />
<strong>Fire</strong> gas explosion<br />
When unburnt gases<br />
from an underventilated<br />
fi re fl ow<br />
through leakages into<br />
a closed space<br />
connected to the fi re<br />
room, the gases there<br />
can mix very well<br />
with air to form a<br />
combustible gas<br />
mixture. If these gases<br />
are ignited, a fi re gas<br />
explosion may occur.<br />
Backdraft<br />
Backdraft is the<br />
burning of heated<br />
gaseous products of<br />
combustion when<br />
oxygen is introduced<br />
into an environment<br />
that has a depleted<br />
supply of oxygen due<br />
to fi re. This burning<br />
often occurs with<br />
explosive force.<br />
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