7.4.1 Spaces in which flammable gases may accumulate
should be provided with effective ventilation to the satisfaction
of the Administration.
7.4.2
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(a) In general, the control and closure of ventilation
openings to fire hazard areas should be capable of being operated
from outside the area and also from inside where necessary.
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(b) The Administration should, in addition, consider
the need to have similar arrangements for other compartments.
7.4.3 All ventilation fans should be capable of
being stopped from outside the spaces which they serve.
7.4.4 Where a compartment is likely to be occupied,
ventilation controls for that compartment should also be operable
from within.
7.4.5 Fire hazard areas should have separate ventilation
systems and ventilation ducts. Ventilation ducts for fire hazard areas
should not pass through other spaces, and ducts for ventilation of
other spaces should not pass through fire hazard areas. The Administration
may permit relaxations from these requirements, provided that the
ducts have adequate fire integrity and insulation or automatic fire
dampers are fitted close to the boundaries penetrated.
7.4.6 An effective ventilation system to give
a minimum of 10 changes per hour should be provided in special category
spaces with means provided at the control station to indicate the
loss or reduction in operation of the system.