Oil Charge; Safety Devices Settings - Liebert CRH 004 Service Manual

Charge with the compressor in operation, connecting the
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cylinder with the charge connector after the thermostatic ex-
pansion valve.
Flush the connection pipe between the cylinder and the
charging point; tighten the seal joint and then start charging
the unit. It is imperative that the cylinder is weighed both be-
fore and after the operation.
For the units with R407C the refrigerant charge must be
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made exclusively with liquid refrigerant.
Charge the unit until the bubbles in the sight glass have dis-
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appeared and the working conditions of the entire refrigera-
tion circuit have returned to normal (sub ---cooling and su-
perheating within the limits indicated below).
Measure the superheating as follows:
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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 corresponding
saturated evaporating temperature.
3) The superheating 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)
Verify that the superheating is 5ûC --- 8ûC.
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Measure the sub ---cooling as follows:
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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 temperature.
3) The sub ---cooling is the difference between the two read-
ings.
4) For the units with R407C refer to the pressure gauge
scale indicated with the initials B.P . (Bubble Point)
Verify that at the condenser outlet, sub ---cooling is 3ûC ---
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5ûC.
IT IS IMPORTANT TO CARRY OUT CHARGING CORRECTLY.
An excess of refrigerant causes an increase in sub ---cooling and

6 --- Safety Devices Settings

The water chiller has already been tested and set up by the manufacturer. The following setting values are suggested in the field.
COMPONENT
Low pressure switch (LP)
High pressure switch (HP)
The settings for the safety valves installed on the machine are indicated below:
MODELS
004---204---206---207---008
006---007---011---014---016
017---020---023---025---028---030---032
consequent operating difficulties in the hot season; a shortage
of charge generates an increase in superheating and possible
compressor stoppages. Whenever work is carried out on the
unit, ensure afterwards that the working conditions are correct,
checking sub ---cooling and superheating.

5.2 --- Oil charge

Contact the Technical Support Department for the specifications
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 PIP-
ING COMPLETELY BEFORE CHANGING THE TYPE OF OIL
USED.
TOP---UPS OF UP TO 20---30% OF THE TOTAL AMOUNT OF
OIL CONTAINED IN THE COMPRESSOR CRANKCASE ARE
PERMITTED; FOR LARGER 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 cal-
2) Isolate the compressor by closing the cock on the liquid line.
3) Connect to the fittings on the compressor body (Schraeder
4) Using a pipe, connect the oil container to the oil service fitting
5) Open the oil service cock, lifting the container, so that the oil
6) Charge the required quantity of oil (make sure the tube al-
7) Stop the oil flow by closing the oil service fitting, open the
SETTING
Operation with R407C/R22
(standard factory setting):
START : 3.6 bar
DIFF. : 0.8 bar
STOP : 2.8 bar
Operation with R407C/R22
(standard factory setting):
STOP : 26 bar
START : 20 bar
DIFF. : 6 bar (fixed)
SETTINGS
28 bar
29 bar
6
ibrations) and fill it with at least twice the amount of oil re-
quired.
valves) and empty it of refrigerant until atmospheric pres-
sure (1 bar) is reached.
on the lower part of the compressor.
flows by gravity.
ways remains below the oil level in the container).
shut---off cock on the refrigerating circuit and restore the
drained refrigerant charge.
reset
NOTES
set diff.
0.2 1.5
0.5
5
bar
bar
SAFETY VALVE
HP side