3 Ventilation of Spaces relating to Gasoline

  3.1 A space containing machinery powered by, or fuel tanks for, gasoline shall have a ventilation system that complies with this regulation and consist of the following:

• .1 for an enclosed space:

  • .1 at least two natural ventilation supply ducts located at one end of the space and that extend to the lowest part of the space or to the bilge on each side of the space; and

  • .2 a mechanical exhaust system consisting of at least two ventilation exhaust ducts located at the end of the space opposite from where the supply ducts are fitted, which extend to the lowest part or the bilge of the space on each side of the space, and which are led to one or more powered exhaust blowers; and

• .2 For a partially enclosed space, at least one ventilation duct installed in the forward part of the space and one ventilation duct installed in the after part of the space, or as otherwise required by the Administration. Ducts for partially enclosed spaces shall have cowls or scoops as required by IV/3.9.

  3.2 A mechanical exhaust system required by regulation IV/3.1.1(b) shall be such as to assure the air changes as noted in Table IV.3.2 depending upon the size of the space.

  3.3 An exhaust blower motor where mounted in any space required to be ventilated by this regulation, shall be located as high above the bilge as practicable. Blower blades shall be non-sparking with reference to their housings.

  3.4 Where a fixed gas fire extinguishing system is installed in a space, all powered exhaust blowers for the space shall automatically shut down upon release of the extinguishing agent.

  3.5 Exhaust blower switches shall be located outside of any space required to be ventilated by this regulation, and shall be of the type interlocked with the starting switch and the ignition switch so that the blowers are started before the engine starter motor circuit or the engine ignition is energised. A red warning sign at the switch shall state that the blowers shall be operated prior to starting the engines for the time sufficient to insure at least one complete change of air in the space served.

  3.6 The area of the ventilation ducts shall be sufficient to limit the air velocity to a maximum of 10 m/s(2,000 ft/min). A duct may be of any shape, provided that in no case will one cross sectional dimension exceed twice the other.

  3.7 A duct shall be so installed that ordinary collection of water in the bilge will not block air flow.

  3.8 A duct shall be of rigid permanent construction, which does not allow any appreciable vapour flow except through normal openings, and made of the same material as the hull or of non-combustible material. The duct shall lead as directly as possible from its intake opening to its terminus and be securely fastened and supported.

  3.9 A supply duct shall be provided at its intake opening with a cowl or scoop having a free area not less than twice the required duct area. When the cowl or scoop is screened, the mouth area shall be increased to compensate for the area of the screen wire. A cowl or scoop shall be kept open at all times, except when the weather is such as to endanger the vessel if the openings are not temporarily closed.

  3.10 A duct opening may not be located where the natural flow of air is unduly obstructed, adjacent to possible sources of vapour ignition, or where exhaust air may be taken into a supply duct.

  3.11 Provision shall be made for closing all supply duct cowls or scoops and exhaust duct discharge openings for a space protected by a fixed gas extinguishing system. All closure devices shall be readily available and mounted in the vicinity of the vent.