Where necessary

Where necessary, main intakes and outlets are to be fitted with gratings to prevent fouling and
the entry of rats and other large vermin.
D.1.4 Where a fixed gas fire-extinguishing system is fitted, ventilation openings of these spaces shall
be capable of being closed from outside the protected space. If the closures are not fitted directly at the
external bulkhead of the protected space the duct between bulkhead, and closing device shall be constructed
of steel having a thickness of at least 3 mm and flange joints are to be sealed by non-combustible
material.
D.1.5 Where individual rooms have separate arrangements for flooding with CO2, the ventilating
system must also be separate. Provision is to be made to remove CO2, after flooding of these spaces.
D.1.6 Electrical machinery and installations (switch cabinets, etc.) are to be protected such that water
particles penetrating into the air ducts will not cause disturbances. Risks of this kind are to be minimized
by appropriate arrangement (water traps) of ducts and air in/outlets.
D.1.7 The number of ventilation openings in watertight subdivisions shall be reduced to the minimum
compatible with the design and proper working of the ship. Where ventilation ducts are routed through
watertight decks and bulkheads, arrangements shall be made to ensure the watertight integrity. If valves
are provided at watertight boundaries to maintain watertight integrity, than the valves are to be capable of
being operated from a control panel located in the navigation bridge, where the position of the shut-off
valves is to be indicated.