General arrangements

D.1 General arrangements
D.1.1 The ventilation systems for machinery spaces of category A, vehicle spaces, ro-ro spaces,
galleys, special category spaces and cargo spaces shall, in general, be separated from each other and
from the ventilation systems serving other spaces.
Exceptions are the galley ventilation systems on cargo ships of less than 4000 gross tonnage and in passenger
ships carrying not more than 36 passengers, which need not be completely separated, but may be
served by separate ducts from a ventilation unit serving other spaces. In this case, an automatic fire
damper shall be fitted in the galley ventilation ducts near the ventilation unit.
D.1.2 Balance openings or ducts between two enclosed spaces are prohibited except for openings
in or under "B" class doors. Such openings shall be provided only in the lower half of the door. Where
such an opening is in or under a door, the total net area of any such opening or openings shall not exceed
0.05 m2. Alternatively, a non-combustible air balance duct routed between the cabin and the corridor,
and located below the sanitary unit, is permitted where the cross-sectional area of the duct does not exceed
0.05 m2. Ventilation openings, except those under the door, shall be fitted with a grill made of noncombustible
material.