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Table 10 - Upper Limit For Wear Metals And Moisture In Polyolester Oils In Daikin Centrifugal Chillers
Elements
Upper Limit (ppm)
Action
Aluminum
50
1
Copper
100
1
Iron
100
1
Moisture
150
2 &3
Silica
50
1
Total Acid Number (TAN)
0.19
3
Key to Action
1) Re-sample after 500 hours of unit operation.
a) If content increases less than 10%, change oil and oil filter and re-sample at normal interval (usually annual).
b) If content increases between 11% and 24%, change oil and oil filter and re -sample after an additional 500 hours
of operation.
c) If content increases more than 25%, inspect compressor for cause.
2) Re-sample after 500 hours of unit operation.
a) If content increases less than 10%, change filter-drier and re-sample at normal interval (usually annual).
b) If content increases between 11% and 24%, change filter-drier and re-sample after an additional 500 hours of
operation.
c) If content increases more than 25%, monitor for a water leak.
3) If TAN is less than 0.10, system is safe as far as acid is concerned.
a) For TAN between 0.10 and 0.19, re-sample after 1000 hours of operation.
b) For TAN above 0.19, change oil, oil filter, and filter-drier and resample at normal interval
8.2.2
Changing Oil Filters
Daikin chillers are at positive pressure at all times and do not leak contaminated moist air into the refrigerant circuit, th ereby
eliminating the need for annual oil changes. An annual laboratory oil check is recommended to check overall compressor
condition.
CE 079 and Larger Compressors -
The oil filter in these compressors can be changed by simply isolating the filter cavities.
Close the oil discharge line service valve at the oil pump (at the filter on CE126). Remove the filter cover; some foaming
can occur but the check valve should limit leakage from other compressor cavities. Remove the filter, replace with new
element, and replace filter cover using a new gasket. Reopen the valve in the pump discharge line and purge air from the
oil filter cavity.
When machine is operated again, the oil level must be checked to determine if oil needs to be added to maintain the proper
operating level.
8.2.3
Refrigerant Cycle
Maintenance of the refrigerant cycle includes maintaining a log of the operating conditions, and checking that the unit has
the proper oil and refrigerant charge.
At every inspection, the oil, suction, and discharge pressures should be noted and recorded, as well as condenser and
chiller water temperatures.
The suction line temperature at the compressor should be taken at least once a month. Subtracting the saturated
temperature equivalent of the suction pressure from this will give the suction superheat. Extreme changes in subcooling
and/or superheat over a period of time will indicate losses of refrigerant or possible deterioration or malfunction of the
expansion valves. Proper superheat setting is 0 to 1 °F (0.7 °C) at full load. Such a small temperature difference can be
difficult to measure accurately. Another method is to measure the compressor discharge superheat, the difference between
the actual discharge temperature and the saturated discharge temperature. The discharge superheat should be between
14 and 16 °F (8 to 9 °C) at full load. The liquid injection must be deactivated (by closing the valve in the feed line) when
taking the discharge temperature. The superheat will increase linearly to 55 °F (30 °C) at 10% load. The MicroTech
interface panel can display all superheat and subcooling temperatures.
8.2.4
Electrical System
Maintenance
of the electrical system involves the general requirement of keeping contacts clean and connections tight and
checking on specific items as follows:
1. The compressor current draw should be checked and compared to nameplate RLA value. Normally, the actual current
will be lower, since the nameplate rating represents full load operation. Also check all pump and fan motor amperages,
and compare with nameplate ratings.
2. Inspection must verify that the oil heaters are operative. The heaters are insert-cartridge type and can be checked by
ammeter reading. They should be energized whenever power is available to the control circuit, when the oil
temperature sensor calls for heat, and when the compressor is inoperative. When the compressor runs, the heaters
are de-energized. The Digital Output screen and second View screen on the operator interface panel both indicate
when the heaters are energized.
3. At least once a quarter, all equipment protection controls except compres sor overloads should be made to operate
and their operating points checked. A control can shift its operating point as it ages, and this must be detected so the
controls can be adjusted or replaced. Pump interlocks and flow switches should be checked to be sure they interrupt
the control circuit when tripped.
4. The contactors in the motor starter should be inspected and cleaned quarterly. Tighten all terminal connections.
