Fire ventilation

Flashover has still not
taken place and the
risks associated with
fi re ventilation
are small.
108
and making sure that the inlets are at least 1–2 times larger
than the outlets.
Positive pressure ventilation can be used to improve the
effect of the openings. Positive pressure ventilation also
reduces the requirement for the positioning of the outlets.
For positive pressure ventilation the outlets should be 1–2
times larger than the inlets.
Because of the increased supply of air during fi re ventilation,
and because the combustible material and surfaces in
the rooms have been heated up, the fi re can quickly increase
To take into consideration during the initial stage of
the fi re:
• Select outlets carefully, since combustible gases
can ignite in the openings.
• Observe the change in the situation for a short
while before any fi re fi ghting operations are started.
• Implement a rapid suppression operation to avoid
an increase in the intensity of the fi re.
• Use positive pressure ventilation where appropriate
to enable a more rapid suppression/life saving
operation.