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6 | Commissioning
6.5 Refrigerant charge
CAUTION!
Make sure that the suction and discharge line valves are open.
With the compressor switched off, add the liquid refrigerant directly to the condenser or receiver,
breaking the vacuum.
If the refrigerant needs topping up after starting the compressor, it can be topped up in vapour
form on the suction side, or, taking suitable precautions, also in liquid form at the inlet to the
evaporator.
INFO!
6.6 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 allow to run for a minimum of 10 min.
Check the oil level by: The oil must be visible in the sightglass.
ATTENTION! I f larger quantities of oil have to be topped up, there is a risk of
6.7 Avoiding liquid sluggings
ATTENTION! Slugging can damage the compressor and cause coolant to leak.
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.
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 refrigerant in the compressor while the system is at a
standstill.
Wear personal protective clothing such as goggles and
protective gloves!
Avoid overfilling the system with refrigerant!
To avoid shifts in concentration, zeotropic refrigerant blends
(e.g. R407C) must always only be filled into the refrigerating plant
in liquid form.
Do not pour liquid coolant through the suction line valve on
the compressor.
It is not permissible to mix additives with the oil and refrigerant.
Ensure that both shut-off valves are open before starting
the compressor!
oil hammer effects. If this is the case check the oil return!
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