Figure 22: Cold-start valve
Compressor hydraulic system
The compressor hydraulic system moves the movable slide valve (MSV) to load and unload the
compressor. It also moves the movable slide stop (MSS) to increase or decrease the compressor’s
volume ratio (Vi).
The hydraulic cylinder located at the inlet end of the SGC compressor serves a dual purpose. It is
separated by a fixed bulkhead into two sections. The movable slide valve (MSV) section is to the left
of the bulkhead and the movable slide stop (MSS) to the right. Both sections are considered double-
acting hydraulic cylinders as oil pressure moves the pistons in either direction.
Both sections are controlled by double-acting, four-way solenoid valves which are actuated when a
signal from the appropriate microprocessor output energizes the solenoid valve.
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SAB 283-355 A-Frame OHU 6042 and OHU 7650 (including ATEX) Screw Compressor Unit