Flooded type water cooled screw chiller (MIC) MCAC-CTSM-2018-1
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1. Change oil periodically: Check the lubrication oil after every 10,000 hours of continuous running.
When the compressor first runs, change the oil and clean the oil filter after running for 2,000 hours.
Check whether the system is clean and change the oil every 20,000 hours or after 3 years of continuous
running when the system has been running normally.
2. Avoid debris or swarf clogging oil filter as this may cause the bearings to fail. The oil pressure
differential switch will trip when the oil pressure differential reaches the critical point (default: 150 kPa).
The compressor will automatically shut down to prevent the bearings from being damaged by a lack of
lubricating oil.
Caution
Compressor oil is pressurized. Take safety precautions when relieving pressure.
Oil Filter Maintenance
Each compressor has its own internal oil filter and each circuit also has an in-line external filter located
under the external oil separator. The internal oil filter pressure drop should be checked and filter
changed (if necessary) after the initial 2,000 hours of compressor operation. Oil line pressure loss is
monitored by the control and reported for each compressor as the oil filter pressure drop.
Normally the pressure differential (discharge pressure minus oil pressure) is typically less than 150kPa
for a system with clean internal and external filters. To determine the oil pressure drop due to the oil lines
and external filter only, connect a gauge to the oil pressure bleed port. Compare this value to the
discharge pressure read at the touch screen. If this value exceeds 150 kPa, replace the external filter.
Moisture-Liquid Indicator
Clear flow of liquid refrigerant indicates sufficient charge in the system. Note, however, that bubbles in
the sight glass do not necessarily indicate insufficient charge. Moisture in the system is measured in
parts per million (ppm), changes of color of indicator are:
Green—moisture is below 80 ppm;
Yellow-green (chartreuse)—80 to 225 ppm (caution);
Yellow (wet)—above 225 ppm.
Change filter drier at the first sign of moisture in the system.
IMPORTANT: The unit must be in operation for at least 12 hours before the moisture indicator can give
an accurate reading. With the unit running, the indicating element must be in contact with liquid
refrigerant to give a true reading.
Relief Devices
Pressure relief valves
Relief valves are installed on the evaporator, condenser and oil separator. These valves are designed to
provide relief if an abnormal pressure condition arises. Relief valves on the condenser start at 2.07MPa.
These valves should not be capped. If a valve relieves, it should be replaced. If it is not replaced, it may
relieve at a lower pressure compared to the set point, or leak due to trapped dirt from the system which
may prevent resealing.
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