Start-Up - Danfoss BOCK HG88e Operating Manual

8 | Commissioning

8.6 Start-up

WARNING
Check that the safety and protection devices (pressure switch, motor protection, electrical
contact protection measures, etc.) are all functioning properly.
Switch on the compressor and let it run for at least 1 minute at a frequency of at least 50 Hz.
Only then may the speed of the compressor be reduced.
Check the oil level by: The oil must be visible in the sight glass.
ATTENTION I f larger quantities of oil have to be topped up, there is a risk of
8.7 Avoiding slugging
ATTENTION Slugging can damage the compressor and cause refrigerant to
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). For HC and LG compressors see chapter 5.3.
The system must reach a state of equilibrium.
Particularly in critical systems (e.g. several evaporator points), measures are recommended such
as replacement of liquid traps, solenoid valve in the liquid line, etc.
There should be no movement of coolant whatsoever while the compressor is at a standstill.
The use of a check valve is strongly recommended, especially for heat pump applications.
Otherwise there is a risk of back condensation, which can cause compressor damage.
© Danfoss | Climate Solutions | 2023.10
Ensure that both shut-off valves are open before starting the
compressor!
oil hammer effects.
If this is the case check the oil return!
leak.
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