Section 8 Low pressure compressed air systems

8.1.1 The requirements of this Section are applicable to low pressure (LP) compressed air systems intended for essential pneumatic control and instrumentation purposes.

8.1.2 Compressed air systems used for diesel engine starting are to comply with the requirements of Pt 10, Ch 1, 8.5 Starting air pipe systems and safety fittings and Pt 10, Ch 1, 9 Starting arrangements.

8.2.1 Where LP air is not derived from the starting air system, at least two LP air compressors are to be provided. The output of any one compressor is to match the total demand of all essential users. The system is to be arranged for auto-start of the compressors.

8.2.2 If only one LP air compressor is to be provided, a cross-connection to the starting air system is to be made via a reducing valve/cross-connection station.

8.2.3 Where LP air is derived only from the starting air system, each starting air compressor is to have sufficient capability of supplying the total demand on the LP air system.

8.3.1 The LP air system and any associated air receivers are to be configured to provide sufficient stored energy to supply LP compressed air without the pressure in the system falling below a level that is insufficient for the operation of all essential users. See also Pt 16, Ch 1, 2.5 Control systems 2.5.10.

8.3.2 All air receivers are to comply with the requirements of Pt 15, Ch 4 Pressure Plant as applicable.

8.3.3 Stop valves on air receivers are to permit slow opening to avoid sudden pressure rises in the piping system.

8.4.1 Drain pots with drain valves are to be provided throughout the distribution system at all low points.

8.4.2 Pipelines that are situated on the low pressure side of reducing valves/stations and that are not designed to withstand the full pressure of the source supply, are to be provided with pressure gauges and with relief valves having sufficient capacity to protect the piping against excessive pressure.

8.4.3 In-line filters capable of being cleaned/changed without interrupting the flow of filtered air are to be fitted in the system.

8.5.1 Where valves, which are required by the Rules to be capable of being closed from outside a machinery space in the event of a fire, have pneumatic closing arrangements, the arrangements are to comply with Pt 15, Ch 3, 8.5 Pneumatic remote control valves 8.5.2.

8.5.2 A dedicated air receiver is to be fitted to supply compressed air to the valves. This air receiver is to be located outside the machinery space.

8.5.3 The air receiver is to be maintained fully charged from the main LP air system via a non-return valve located at the air receiver inlet which is to be locked in the open position.

8.5.4 In the case of passenger craft, a permanently attached hand-operated compressor capable of charging the air receiver is to be provided in the space in which the air receiver is located.

8.5.5 The capacity of the air receiver is to be sufficient to operate all valves and any other essential supplies such as ventilation flaps without replenishment.

8.5.6 Where valves, which are required by the Rules to be capable of being operated in the event of a flooding, are pneumatically operated, the arrangements are to comply with Pt 15, Ch 3, 8.5 Pneumatic remote control valves 8.5.7.

8.5.7 A compressor is to be fitted to supply compressed air to the valves. This compressor is to be accessible and operable in the flooding condition. Where valves are required by the Rules to be operable from above the bulkhead deck, the compressor is to be located above the bulkhead deck. Consideration shall be given to alternative arrangements which are equivalent to those required by the Rules.

8.6.1 The control, alarm and monitoring systems are to comply with Pt 16, Ch 1 Control Engineering Systems.