Profroid QUIETCO2OL MC Notice D'instruction page 78

COMMISSIONING
– As vapor is drawn from the R744 cylinders, pressure and temperature inside the
cylinder will decrease. Frosting on the bottom exterior of the cylinder is evidence
that some R744 liquid evaporated inside. The reduction in pressure also causes a
slower flow rate of vapor into the system. Once the flow from the cylinder has slowed
to a low level, the cold cylinder should be disconnected and allowed to warm.
After the cylinder warms, additional R744 can be removed. In the meantime,
another warm tank can be connected to the system to continue the charging process.
– After making sure that all valves are open starts all compressors by using the
electronic controller and check that all compressors operates without special noise.
(Check that LP pressure switches can deactivate compressors) It is recommended to
start with the compressors of the booster part when it exists.
– 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 expansion valves by setting the MOP -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 BP manometers of the
MT and LT control unit
– Pressure should not increase (start the compressors to increase the pressure drop if
necessary and thus not introduce too much CO2 unnecessarily)
– If pressure rises the causes can be:
– Non-tightness of expansions valves
– A connection problem on the expansion valve (In backup mode the
controller continues to supply power if the superheat sensor is out of order
for example, or the connection of the expansion valve supply is not correct).
In this case the expansion valve is operating.
– A tube crossing between liquid and suction (the diameters are sometimes the
same).
– If the pressure does not rise or rise very low, 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 by using the charge 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 bars, to complete the filling of the installation; By "artificially"
maintaining the intended transcritical operating conditions.
WARNING
– The filling operation in Transcritical mode must be maintained in order to to be close
to the low level alarm.
– In Subcritical regime the level of liquid CO2 can increase considerably.
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