Oil Filling - Profroid MiniCO2OLcompact Notice D'instructions

6.1.6

Oil filling

Fill up to the bottom of the higher level sight glass on the receiver. The separator should also be filled with approximately 0.5 liters of
oil. The oil will be introduced inside the oil receiver.
In all cases, the oil filling must be done while the machine is under vacuum and using a vacuum pump.
Once these operations have been carried out, the operation of the vacuum pump will be maintained for at least 1 hour in order to
evacuate the air and the moisture possibly contained in the oil.
6.1.7 Filling with refrigerant
The filling of CO2 with less than 10 ppm of moisture is carried out after the system has been vacuumed. Quality required is R744.
Filling in gas phases is mandatory when the installation is under vacuum, until the pressure in the whole installation will be above 6
bar (triple point of the fluid: 5.2 Absolute bar) . A value of 15 bar is recommended.
After making sure that all valves are open, start all compressors using the electronic controller and check that all compressors
operate without special noise (check that the LP pressure switches do no switch off the compressors). It is recommended to start
with the compressors of the booster part when existing.
If all the compressors are operational or after having made them operational and before introducing the fluid in liquid form via the
liquid line (charging valve at the filter drier):
Close the AKV expansion valves by setting the MOP at -50 ° C
Manually check the activation of the Transcritical High Pressure Expansion Valve.
Manually check the activation of the Medium Pressure Flash gas valves on the receiver
Set these valves to automatic operation, turn on the fan motors of the Gas Cooler
Introduce the liquid CO2 in a small amount first through the service valve on the liquid line and check the pressure rise at the
LP manometers of the MT and LT stages.
Pressure should not increase (start the compressors to increase the pressure drop if necessary and thus do not introduce too much
CO2 unnecessarily)
If pressure rises, the causes can be:
Non-tightness of AKV expansions valves
A connection problem on the AKV (in backup mode the controller continues to supply power if the superheat sensor is out
of order for example, or the connection of the AKV supply is not correct). In this case the expansion valve is operating.
A wrong pipe connection between liquid and suction (the diameters are sometimes the same).
If the pressure does not rise or rises very slowly, the charging operation can be continued by starting a compressor on each
stage, preferably the one with the VSD.
Check the operation of the HP valve, the optimum pressure must be adjusted after a few minutes to be very close to the calculated
value.
Beyond this pressure, a liquid phase charge is still possible using the charging service valve on the liquid receiver. Start filling
only at a minimum oil temperature of 35-40 ° C.
Start a single MT compressor when the suction pressure of the compressors reaches 25 to 30 bar, to complete the filling of the
installation; maintaining "artificially" the intended transcritical operating conditions.
WARNING!
The refrigerant charge is a critical operation to ensure proper operation of the installation all year long.
Depending on the installation configuration (volume and position of the gas cooler, length of the liquid line, heat recovery
module or not, gas cooler by-pass or not in heat recovery mode, load variations from the consumers, ...), important variations
of liquid refrigerant charge inside the receiver can be observed. They are particularly noticeable between transcritical and
subcritical modes.
In case of any doubt on the refrigerant charge needed for the installation, plan at the design phase, when sizing the
installation, a bigger volume for the liquid receiver of the rack or an additional receiver if necessary depending on the
specific layout of the equipments inside the machine room.
It is highly recommended to keep checking the impact of the refrigerant charge over the year, checking the filling level of
the liquid receiver and the temperature at the consumers. This will ensure that the amount of refrigerant is well adapted to
the fluctuations of the system over the seasons and different operating modes.
6.1.8 Safety tests and presets
HP safety pressure switches
They are connected to the compressor discharge
Compressors Booster stage: PSH cut-off set at 0.9 x PS
Compressors to Gas Cooler: PZH cut-off at 108 Bar