1 The term "free sectional area" means, even in the case of a pre-insulated duct, the area calculated on the basis of the inner diameter of the duct.
2 Where a thin plated duct with a free sectional area equal to, or less than, 0.02 m2 passes through "A" class bulkheads or decks, the opening should be lined with a steel sheet sleeve having a thickness of at least 3 mm and a length of at least 200 mm, divided preferably into 100 mm on each side of the bulkhead or, in the case of the deck, totally laid on the lower side of the decks pierced.
1 Manual closing may be achieved by mechanical means of release or by remote operation of the fire damper by means of a fail-safe electrical switch or pneumatic release (spring-loaded, etc.) on both sides of the division.
2 The fire dampers should be easily accessible. Where they are placed behind ceilings or linings, these latter should be provided with an inspection door on which a plate reporting the identification number of the fire damper. Such plate and identification number should be placed also on any remote control required.
1 Galley ventilation systems should be separated from the ventilation systems serving other spaces. On cargo ships of less than 4,000 gross tonnage and in passenger ships carrying not more than 36 passengers, galley supply ventilation may be achieved by separate ducts from the ventilation unit and an automatic fire damper fitted in the galley ventilation duct near the ventilation unit. When passing through accommodation spaces, service spaces and control stations, galley ventilation ducts should be constructed of "A" class standard having a thickness as per regulation II-2/16.3.1.1 for the entire length passing through such spaces.
2 The ventilation systems for machinery spaces of category A, car deck spaces, ro-ro cargo spaces, special category spaces and cargo spaces, in general, should be separated from each other and from the ventilation systems serving other spaces.
Equally effective local closing arrangements means that in case of ventilators these should be fitted with fire dampers or smoke dampers which could be closed easily within the control station in order to maintain the absence of smoke in the event of fire.
Manual closing may be achieved by mechanical means of release or by remote operation of the fire damper by means of a fail-safe electrical switch or pneumatic release (spring-loaded, etc.) on both sides of the division.
The controls should be easily accessible as well as prominently and permanently marked and should indicate whether the shutoff is open or closed.