HSO 2024 to HSO 2035 Installation, Operation and Maintenance Manual
Issue 1.2 : 03/10
Publication 2-119
Page 15 of 94
The movement of the slide valves is effected by oil pressure acting on a
piston which is connected to the valves by a yoke. Pressurised oil is
taken from the lubrication system and fed through solenoid valves which
respond to signals from the plant control system. The solenoid valves
direct oil to each end of the compressor capacity control cylinder via two
connections positioned at the rear of the main casing, moving the
capacity control piston in the appropriate direction to load or unload the
compressor. Oil from the other end of the capacity control cylinder is
vented to the low pressure (LP) side of the system via a connection in the
suction line before the suction non-return valve.