6.4.1 Hazardous enclosed spaces should be ventilated.
Where mechanical ventilation is applied it should be such that the
hazardous enclosed spaces are maintained with underpressure in relation
to the less hazardous spaces or areas and non-hazardous enclosed spaces
are maintained in overpressure in relation to adjacent hazardous locations.
6.4.2 All air inlets for hazardous enclosed spaces
should be taken from non-hazardous areas. Where the inlet duct passes
through a more hazardous area the inlet duct should have overpressure
in relation to this area
6.4.3 Each air outlet should be located in an
outdoor area which, in the absence of the considered outlet, is of
the same or lesser hazard than the ventilated space.