Clean and dry control air is essential for efficient, trouble-free operation of a ship's pneumatic control air system.

(a) Sketch and describe a low pressure control air systems used on board ships, showing various arrangements to deal with dust, oil and moisture as well as safety systems. (8)

(b) Explain using a line diagram, arrangement provided, to reduce the air pressure to 7/8 bars, required for control air system. (8)