GEA Grasso - Switching off; Normal Shutdown; Shutting down for a Lengthy Period; Measures During Stoppages

OPERATING INSTRUCTIONS
CO
2
/NH
3
CASCADE UNIT
250 - 1000 KW
22 _551511_om_kas_gbr_1_.doc
1.8.3.1 Monthly
1.8 Switching off
• Check that a gauge pressure is constantly
applied in the cascade. Use a leak detector to
check the cascade for leaks once a month.
1.8.1 Normal shutdown
Shutting down for short stoppages (< 48 h)
• Start up the oil pump for approx 5 minutes.
• Staged output reduction of NH
and CO
2 3
compressors down to minimum load
• Manually rotate the compressor shaft (min 10
revolutions).
compressor first, then NH
CO
2 3
compressor
1.8.3.2 Four weeks before putting back into service
• Shut down coolant, heat transfer medium and
cooling water system as necessary
• Check the moisture content and ageing
condition of the refrigerator oil. Analyse the oil
and compare the values with the fresh oil data.
Grasso advises an oil change after 1 year
(ammonia, see Maintenance Instructions).
• If necessary, shut down ancillary drives
• Leave the valves in the operating position
1.8.2 Shutting down for a lengthy period
• Check the insulation resistance of the drive
motors (see electric motor's User Manual).
Shutting down for lengthy stoppages (> 48 h)
• Switch on the oil pump.
— Staged output reduction of CO
2
and NH
3
compressors down to minimum load
• Check the cascade for leaks.
compressor first, then NH
CO
2 3
compressor
1.8.4 Putting back into service after approx 1
year
— Close the shut-off valves on the intake side and
outlet side (or shuttable check valves).
• Change the oil filter inserts (see Maintenance
Instructions).
— Switch off CO
refrigerant pump
2
— Remove the heat transfer medium from service
• Switch the oil heater on at least one hour before
starting the cascade.
— Close the shut-off valves (or shuttable check
valves) in economizer suction line.
• Open the shut-off valves on the intake side and
the discharge side (or shuttable check valves).
— Cut-off the refrigerant supply to the
thermosyphon oil cooler.
• Open the shut-off valves (shuttable check valves)
in the economizer suction line.
— Close the manual cut-off valve of the refrigerant
injection.
• Open the refrigerant supply to the
thermosyphon - oil cooler.
— Switch off the oil heater.
• Open the manual shut-off valve of the
refrigerant injection.
— Switch off the main switch of the power supply
system for the cascade
• Remove all non-condensable gases are removed
by venting. To this end, check the condensing
pressure and temperature (see parameter list).
Caution!
The main switch for the auxiliary
refrigeration unit remains switched
on!
• Check the oil collection sump and empty if
necessary.
— Ensure you cover the venting slots of the
electric motors!
• Switch on the compressor and observe the
operating instructions of the electrical
switchgear. Functional run of the cascade to
check the sensor technology and actuators
(function and display accuracy).
1.8.3 Measures during stoppages
In the event of lengthy stoppages, which last longer
than half a year, despite the gauge pressure in the
cascade, the moisture contant of refrigerant and the
refrigerator oil must be checked. The moisture
contant must not differ substantially from the initial
values.