7.0 Ventilation

  7.1 Fuel pump room(s), fuel storage room(s) and other closed spaces which contain fuel handling equipment, and to which regular access is required during cargo handling operations, are to be provided with permanent ventilation system(s) of the mechanical extraction type.

  7.2 The ventilation system(s) should be capable of being operated from outside the compartment being ventilated and a notice should be fixed near the entrance stating that no person is to enter the space until the ventilation system has been in operation for at least 15 minutes.

  7.3 The ventilation system(s) should be capable of 20 air changes per hour, based on the gross volume of the pump room or space.

  7.4 Protection screens of not more than 13 mm square mesh should be fitted in outside openings of ventilation ducts, and ventilation intakes should be so arranged as to minimise the possibility of re-cycling hazardous vapours from any ventilation discharge opening. Vent exits are to be arranged to discharge upwards.

  7.5 The ventilation should be interlocked to the lighting system (except emergency lighting) such that the pump room lighting may only come on when the ventilation is in operation. Failure of the ventilation system is not to cause the lighting to go out and failure of the lighting system is not to cause loss of the ventilation system.

  7.6 Non - Sparking Fans for Hazardous Areas

  7.6.1 The air gap between impeller and housing of ventilation fans should be not less than 0,1 of the impeller shaft bearing diameter or 2 mm whichever is the larger, subject also to compliance with 7.6.2.5. Generally, however, the air gap need be no more than 13 mm.

  7.6.2 The following combinations of materials are permissible for the impeller and the housing in way of the impeller:

• .1 Impellers and/or housings of non-metallic material, due regard being paid to the elimination of static electricity.

• .2 Impellers and housings of non-ferrous metals.

• .3 Impellers and housings of austenitic stainless steel.

• .4 Impellers of aluminium alloys or magnesium alloys and a ferrous housing provided that a ring of suitable thickness of non-ferrous material is fitted in way of the impeller.

• .5 Any combination of ferrous impellers and housings with not less than 13 mm tip clearance.

• .6 Any combination of materials for the impeller and housing which are demonstrated as being spark proof by appropriate rubbing tests.

  7.6.3 The following combinations of materials for impellers and housing are not considered spark proof and should not be permitted:

• .1 Impellers of an aluminium alloy or magnesium alloy and a ferrous housing, irrespective of tip clearance.

• .2 Impellers of a ferrous material and housings made of an aluminium alloy, irrespective of tip clearance.

• .3 Any combination of ferrous impeller and housing with less than 13 mm tip clearance, other than permitted by 7.6.3.2.

  7.6.4 Electrostatic charges both in the rotating body and the casing should be prevented by the use of antistatic materials (i.e. materials having an electrical resistance between 5 x 104 ohms and 108 ohms), or special means should be provided to avoid dangerous electrical charges on the surface of the material.

  7.6.5 Type approval tests on the complete fan should be carried out to the satisfaction of the Classification Society.

  7.6.6 Protection screens of not more than 13 mm square mesh should be fitted in the inlet and outlet of ventilation ducts to prevent the entry of objects into the fan housing.

  7.6.7 The installation of the ventilation units on board should be such as to ensure the safe bonding to the hull of the units themselves.