GEA Bock HGZ7 - Manual (Page 30)

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7| Commissioning
ATTENTION To avoid liquid shocks on the HP stage, the expansion valve may
only be opened approx. 15-20 seconds after the compressor is
switched on (full load operation).
At compressor shut-down:
Close the solenoid valve approx. 15 - 20 seconds before the com-
pressor is switched off.
7.7 Avoiding slugging
To prevent slugging:
The complete refrigeration system must be properly designed.
All components must be compatibly rated with each other with regard to output
(particularly the evaporator and expansion valves).
Suction gas superheat at the compressor input should be min. 7 - 10 K. (check the setting
of the expansion valve).
The system must reach a state of equilibrium.
When selecting the evaporator expansion valve, pay attention to correction factors for liquid
subcooling. Avoid transfer of refrigerant into the compressor when the system is at a
standstill.
The use of a liquid separator is recommended.
ATTENTION Slugging can damage the compressor and cause refrigerant to
leak.