Fire ventilation

112
Piercing nozzle
(fog nail).
Alternatives or supplements to fi re ventilation, for
example the use of piercing nozzles, should be considered
when the fi re is strongly ventilation controlled.
If the fi re gases can be cooled down in this way it will be
possible to implement fi re ventilation or internal suppression
with signifi cantly less risks. Filling with foam can be
another alternative, which however assumes that the requisite
opening can be made. The size of such an opening is
often less than what would be needed for fi re ventilation. It
can often be appropriate to fi rst secure the adjacent rooms
or buildings before measures are taken for the fi re room. In
the case of ventilation-controlled fi res it can be possible to
save lives in the fi re room, since the impact of the heat on
trapped persons can be relatively moderate.
Ventilation-controlled fi res involve large risks, since the
fi re gases contains large volumes of uncombusted gases. In
the event of rapid mixing of large volumes of air there is a
risk of backdraft. Above all there is a risk of very rapid fl ashover
scenarios when fi re ventilation is implemented.
To take into consideration during ventilation-controlled
fi res:
• Consider alternatives or supplementary methods to
fi re ventilation, for example cooling of the hot
gases with piercing nozzles.
• Observe great care during the implementation of
fi re ventilation.
• Observe great care during the choice of outlets,
both in view of fl ames that can come out from the
fi re area and a possible backdraft.
• Avoid turbulent mixing of fresh air in the fi re gases.
• Have a well-planned and coordinated ventilation
and suppression operation, since the supply of air
will increase the intensity of the fi re and the risk of
spreading the fi re and fi re gases.