Section 2 Ventilation

201. General

1. Attention is to be given to ventilation inlet and outlet location and airflow in order to minimize the possibility of cross contamination.

2. Inlets are to be located in non-hazardous areas as high and as far away from any hazardous area as practicable.

3. Each air outlet is to be located in an outdoor area which, in the absence of the considered outlet, is of the same or lesser hazard than the ventilated space.

4. Ventilation for hazardous areas is to be completely separate from that used for non-hazardous areas.

202. Ventilation of hazardous areas

1. Where the ventilation duct passes through a hazardous area of a higher level, the ventilation duct should have overpressure in relation to this area and where the ventilation duct passes through a hazardous area of a lower level, the ventilation duct should have under-pressure in relation to this area.

2. The arrangement of ventilation inlet and outlet openings in the space is to be such that the entire space is efficiently ventilated, giving special consideration to location of equipment which may re- lease gas, and to spaces where gas may accumulate.

3. The outlet air from Zone 1 and Zone 2 spaces is to be led in separate ducts to outdoor locations.

The internal spaces of such ducts belong to the same Zone as the inlet space.

4. Air inlet ducts designed for constant relative under-pressures are to be rigidly constructed to avoid air leaks.

5. Fans are to be designed so as to reduce the risk that sparks may occur.

6. All areas are to be adequately ventilated. Hazardous enclosed spaces are to be ventilated with un- der- pressure in relation to adjacent non-hazardous locations and non-hazardous enclosed spaces are maintained in overpressure in relation to adjacent hazardous locations. To ensure that a negative pressure condition exists in any enclosed Zone 1 and Zone 2, supply and exhaust fans are to be interlocked so that supply fans cannot be activated without first engaging exhaust fans.

7. Means are to be provided for shutdown of ventilation fans and closing external openings from out- side the spaces served, in the event of fire or detection of combustible or hydrogen or hydrogen sulfide gas.

The requirements of this Section should be substituted for SOLAS regulations II-2/4.5.2.6 and II- 2/4.5.4.

203. Mechanical Ventilation in the Cargo Area

The requirements of this Section should be substituted for SOLAS regulations II-2/4.5.2.6 and II-2/4.5.4.

1. Spaces required to be entered during normal cargo handling operations (IGC Code 12.1)

(1) Electric motor rooms, cargo compressor and pump rooms, other enclosed spaces which contain

cargo handling equipment and similar spaces in which cargo handling operations are performed should be fitted with mechanical ventilation systems capable of being controlled from outside such spaces. Provision should be made to ventilate such spaces prior to entering the compart- ment and operating the equipment and a warning notice requiring the use of such ventilation should be placed outside the compartment.

(2) Mechanical ventilation inlets and outlets should be arranged to ensure sufficient air movement through the space to avoid the accumulation of flammable or toxic vapours and to ensure a safe working environment, but in no case should the ventilation system have a capacity of less than 30 changes of air per hour based upon the total volume of the space. As an exception, gas-safe cargo control rooms may have eight changes of air per hour.

(3) Ventilation systems should be fixed and, if of the negative pressure type, permit extraction from either the upper or the lower parts of the spaces, or from both the upper and the lower parts, depending on the density of the vapours of the products carried.

(4) In rooms housing electric motors driving cargo compressors or pumps, spaces except machinery spaces containing inert gas generators, cargo control rooms if considered as gas-safe spaces and other gas-safe spaces within the cargo area, the ventilation should be of the positive pressure

type.

(5) In cargo compressor and pump rooms and in cargo control rooms if considered gas-dangerous, the ventilation should be of the negative pressure type.

(6) Ventilation exhaust ducts from gas-dangerous spaces should discharge upwards in locations at least 10 m in the horizontal direction from ventilation intakes and openings to accommodation spaces, service spaces and control stations and other gas-safe spaces.

(7) Ventilation intakes should be so arranged as to minimize the possibility of re-cycling hazardous vapours from any ventilation discharge opening.

(8) Ventilation ducts from gas-dangerous spaces should not be led through accommodation, service and machinery spaces or control stations, except as allowed in Pt 7, Ch 5, Sec 16 of Rules for the Classification of Steel Ships.

(9) Electric motors driving fans should be placed outside the ventilation ducts if the carriage of flammable products is intended. Ventilation fans should not produce a source of vapour ignition in either the ventilated space or the ventilation system associated with the space. Ventilation fans and fan ducts, in way of fans only, for gas-dangerous spaces should be of non sparking construction defined as:

(A) impellers or housing of nonmetallic construction, due regard being paid to the elimination of static electricity;

(B) impellers and housing of nonferrous materials;

(C) impellers and housing of austenitic stainless steel; and

(D) ferrous impellers and housing with not less than 13 mm design tip clearance.

Any combination or an aluminium or magnesium alloy fixed or rotating component and a

ferrous fixed or rotating component, regardless of tip clearance, is considered a sparking hazard and should not be used in these places.

(10) Spare parts should be carried for each type of fan on board referred to in this Section.

(11) Protection screens of not more than 13 mm square mesh should be fitted in outside openings of ventilation ducts.

2. Spaces not normally entered (IGC Code 12.2)

Hold spaces, interbarrier spaces, void spaces, cofferdams, spaces containing cargo piping and other spaces where cargo vapour may accumulate, should be capable of being ventilated to ensure a safe environment when entry into the spaces is necessary. Where a permanent ventilation system is not provided for such spaces, approved means of portable mechanical ventilation should be provided. Where necessary owing to the arrangement of spaces, such as hold spaces and interbarrier spaces,

essential ducting for such ventilation should be permanently clear of personnel access openings, and should comply with the Classification of Steel Ships.

installed. Fans or blowers should be

Pt 7, Ch 5, 1201. 9 of Rules for