OPERATING INSTRUCTIONS
CO
2
/NH
3
CASCADE UNIT
250 - 1000 KW
12 _551511_om_kas_gbr_1_.doc
After the leak test has finished and it has been
established that the cascade is free of leaks, reinstall
any instrumentation and control devices removed.
Warning!
Check the oil grade to be charged. See
contract / project or Grasso
recommendation.
1.6.2.2 Drying, vacuum
After the leak test has been completed, the system is
evacuated and subjected to a vacuum test for 3
hours. Evacuation is used to remove air and moisture
from the system.
The quantity of oil to be charged for the respective
compressor is given in the compressor
documentation.
During the 3 hour period the vacuum reached may
rise by maximum 5 torr.
Warning!
Due to the use of selected components,
the refrigerator oils tend to absorb more
moisture. Therefore, when charging a
compressor the oil should be allowed to
come into contact with air for a short
time only. The contents of an opened
drum have to be used up within one
working day, provided the drum is
properly closed between charging.
fig. 1: Vacuum required to remove moisture from
refrigerating plants
A Vacuum
B Room or wall temperature
After the required vacuum has been reached
measured values must be logged hourly. After the
negative pressure (vacuum) value, the temperatures
in the machine house and the outdoor temperatures
in the shade must be entered in the log. After the
vacuum test the pressure must be equalized with
refrigerant.
Warning!
Shut off the oil pump during evacuation!
1.6.2.3 Oil charge
The compressor is filled (charged) with oil in the NH
3
or CO
2
circuit according to the compressor's user
instructions.
The vacuum present in the cascade unit before
pressure compensation can be utilized for the first oil
charge. A separate oil recharging pump is required
after the pressure compensation and for refilling
with oil.
1.6.2.3.1 Oil charge - NH
3
side
The connection of the oil draining/oil charging shut-
off valve (090) must be connected with the oil
charging tank.
Switch the valves to the operating position before
charging with oil.
Open the shut-off valve (090) until the oil level has
reached the top third of the oblong sight glass in the
oil separator sump.
The oil separator is generally charged with oil via the
oil cooler.
When charging with oil for the first time, oil must be
charged via the service valve (135) too. To this end
the shut-off valve (065) must then be closed.
1.6.2.3.2 Oil charge - CO
2
side
The connection of the oil draining/oil charging shut-
off valve (5720) must be connected with the oil
charging tank.
Before charging with oil, switch the valves to the
operating position.
Open the shut-off valve (5720) until the oil level has
reached the top third of the oblong sight glass in the
oil separator sump.
The oil separator is generally charged with oil via the
oil cooler.
When charging with oil for the first time, oil must be
charged via the service valve (5710) too. To this end
the shut-off valve (5305) must then be closed.
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