AGL_Unit_ZX_Small_E_Rev03
15
4
Start-up & operation
Before commissioning, ensure that all valves on the refrigeration unit are fully opened.
4.1 Evacuation
CAUTION
System pressure below atmospheric pressure! Compressor damage!
Never energize the unit without minimum refrigerant charge in the system.
There is a risk of malfunction of the unit in deep vacuum operation which can
cause compressor damage.
IMPORTANT
The evacuation procedure is based upon achieving an actual system
vacuum standard and is NOT TIME DEPENDENT! The installation has to be
evacuated with a vacuum pump before commissioning. Proper evacuation
reduces residual moisture to 50 ppm. The installation of adequately sized
access valves at the furthest point from the compressor in the suction and
liquid lines is advisable. The system must be evacuated down to less than
3 mbar. If required break the vacuum with dry nitrogen. Pressure must be
measured using a vacuum pressure gauge on the access valves and not on
the vacuum pump. This serves to avoid incorrect measurements resulting
from the pressure gradient along the connecting lines to the pump.
4.2 Charging procedure
4.2.1
Refrigerant charging procedure
CAUTION
Service valve closed! Compressor damage!
Do not charge the unit with
vapour (gas). The suction service valve must not be fully closed at any time
when the compressor is running. To do so would cause damage to the
compressor in the same manner as explained above. This valve is provided
for ease of connection and for the fitting of service gauges without removing
the unit panel.
IMPORTANT
Inadequate charge! Overheating!
The scroll compressor design requires
system charging as quickly as possible with liquid refrigerant into the liquid
line. This will avoid running the compressor under conditions whereby
insufficient suction gas is available to cool not only the motor but also the
scrolls. Temperature builds up very quickly in the scrolls if this is not done.
Pre-charging must be carried out with liquid refrigerant through the service valve on the liquid line.
It is advisable to pre-fill the suction side with a partial charge to avoid vacuum operation. Further
charging can be carried out by carefully filling refrigerant through the suction line while
simultaneously checking the sight glass. The charge is sufficient if no more bubbles appear in the
sight glass.
Recommendation is to break vacuum in the system with partial charge of refrigerant, then start the
system.
After checking the refrigerant quantity in the sight glass, put the rubber cap back into place as
shown in
Figure 13
.
Figure 13: Sight glass & rubber cap
