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© Danfoss | Climate Solutions | 2023.06
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Commissioning
6.7 Pressure switch
Check that the safety and protection devices (pressure switch, motor protection, electrical contact
protection measures, etc.) are functioning properly.
Switch on the compressor and let it run for at least 10 minutes.
The machine should reach a state of equilibrium.
Check the
oil level
: The oil level must be visible in the sight glass.
After a compressor is replaced, the oil level must be checked again.
Suitably adjusted pressure switches according to EN 378 or a corresponding safety standard that
switch off the compressor
before reaching
the maximum permissible operating pressure must be
installed in the system. The pressure reduction for the pressure switches can occur either at the
suction and pressure lines.
ATTENTION
If larger quantities of oil have to be topped up, there is a risk of oil
impact effects. If this is the case, check the oil return!
6.6 Start-up
6.8
Avoiding slugging
To prevent slugging:
The complete refrigeration plant 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 superheating at the compressor input
should be > 10 K
(check the setting of the
expansion valve).
Regard oil temperature and pressure gas temperature. (The pressure gas temperature has to be
high enough min. 50 °C, so the oil temperature is > 30 °C).
The system must reach a state of equilibrium.
Particularly in critical systems (e.g. several evaporator points), measures such as the use of liquid
traps, solenoid valve in the liquid line, etc. are recommended.
There should be no movement of refrigerant in the compressor while the system is at a
standstill.
ATTENTION Slugging can result in damage to the compressor and cause
refrigerant to leak.
6.9 Filter dryer
Gaseous CO
2
has a significantly lower solubility in water than other refrigerants. At low temperatures
it can therefore cause blocking of valves and filters due to ice or hydrate. For this reason we recom
-
mend the use of an adequately sized filter drier and a sight glass with a moisture indicator.