Vertiv Liebert HPC-M Serie Manuel De Service page 11

charging the unit. It is imperative that the cylinder is
weighed both before and after the operation.
• For the units with R407C the refrigerant charge must
be made exclusively with liquid refrigerant.
S Charge the unit until the bubbles in the sight glass have
disappeared and the working conditions of the entire
refrigeration circuit have returned to normal (sub----
cooling and superheating within the limits indicated
below).
• Measure the superheat as follows:
1) Detect the temperature on the suction line, close to
the bulb of the thermostatic expansion valve, using a
contact thermometer.
2) Connect a pressure gauge (by max. a 30---cm pipe)
with the Schraeder connection and read the corre-
sponding saturated evaporating temperature.
3) The superheat is the difference between the two
readings.
4) For the units with R407C refer to the pressure
gauge scale indicated with the initials D.P. (Dew
Point)
S Verify that the superheat is 5---8
• Measure the sub---cooling as follows:
1) Detect the temperature on the liquid line using a
contact thermometer.
2) Connect a pressure gauge (by max. a 30---cm pipe)
with the Schraeder connection on the liquid line and
read the corresponding saturated condensing tem-
perature.
3) The sub---cooling is the difference between the two
readings.
4) For the units with R407C refer to the pressure
gauge scale indicated with the initials B.P. (Bubble
Point)
S Verify that at the condenser outlet, sub---cooling is
o
4---8 C.
IT IS IMPORTANT TO CARRY OUT CHARGING
CORRECTLY. An excess of refrigerant causes an in-
crease in sub---cooling and consequent operating difficul-
ties in the hot season; a shortage of charge generates an
increase in superheating and possible compressor stop-
pages. Whenever work is carried out on the unit, ensure
afterwards that the working conditions are correct, check-
ing sub---cooling and superheating.
8
o
C.
English
5.2 --- Oil charge
Contact the Technical Support Department for the speci-
fications of the oil to be used for topping up; the oil
changes according to the type of used refrigerant.
NEVER MIX DIFFERENT OILS TOGETHER.
CLEAN THE PIPING COMPLETELY BEFORE
CHANGING THE TYPE OF OIL USED.
TOP---UPS OF UPTO 20---30% OF THE TOTAL
AMOUNT OF OIL CONTAINED IN THE COMPRES-
SOR CRANKCASE ARE PERMITTED; FOR LARG-
ER PERCENTAGES CONTACT THE TECHNICAL
SUPPORT DEPARTMENT.
5.2.1 --- Procedure for oil topping--- up
If there has been any loss of oil then this must be topped
up as follows:
1) Take a clean, dry, transparent container (with volume
calibrations) and fill it with at least twice the amount
of oil required.
2) Isolate the compressor by closing the delivery and suc-
tion cocks (or the one on the liquid line).
3) Connect to the fittings on the compressor body (Schra-
eder valves) and empty it of refrigerant until atmos-
pheric pressure (1 bara) is reaching.
4) Using a pipe, connect the oil container to the oil servi-
ce cock on the lower central part of the compressor.
5) Open the oil service cock lifting the container, so that
the oil flows by gravity.
6) Charge the required quantity of oil (make sure the
tube always remains below the oil level).
7) Close the oil service cock, open the shut---off cocks of
the compressor and on the refrigerating circuit and re-
store the drained refrigerant charge.