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Flooded type water cooled screw chiller (PCB Control)
MCAC-CTSM-2012-11
76
with local customer service centre of Midea after chiller out of warranty, to keep the chiller always under
effective service and guarantee reliable operation.
Note: Repair work caused by incorrect maintenance within warranty will lead to extra charges.
Daily maintenance
The basic work of unit maintenance is to truly record the operation parameters of unit at certain intervals
(e.g. 2hours) everyday. Fill the operation parameter table which contains such key parameters as
high/low pressure, suction/discharge temperature, degree of sub-cooling/overheat degree. True and
complete records of operation parameters are useful for analyzing and forecasting the trend of unit
operation. It’s good for finding and forecasting the problem that may occur and taking measures in time.
For example, by analyzing the record of a whole month, you may find that the temperature difference of
condensing temperature and leaving cooling water temperature may become bigger. It means that the
cooling water is dirty or water hardness is big, and it is scaling constantly. So it’s compulsory to perform
softening process or clean the tubes.
Note: Keeping the normal operation parameters of initial unit commissioning is very useful. It can be
used for comparative analysis to find out the trend of problem.
Scheduled maintenance
General
Take notice of the noise at any time by standing 1m from the unit. Watch the vibration amplitude at all
times to see whether it’s within permitted. Check the voltage of power supply whether it’s within ±10% of
rated voltage at any time.
Visual inspection
Keep the unit clean, if there’s rust, do scaling with iron brush and cover it with antirust paint. Pay
attention to the oil traces (sign of a refrigerant leak) and water traces on pipeline. Check the threaded
connection joints carefully, fasten any loose screw in time. Any time seeing the insulating material flakes
off, stick them with adhesive.
Compressor
For insulation resistance, check it yearly and it should be over 5M
Ω
when measuring with ohmmeter of
DC 500V. When touching the shockproof rubber, it should be elastic, or it means the rubber gets ageing.
Every 3000 hours, make middle inspection of vibration and oil level; every 6000 hours, check the safety
device and protective device to guarantee the normal operation.
Important: The normal oil level is at the middle of sight glass. Adding lubricating oil if the oil level decline
obviously. Inspect the oil quality monthly to see if there’s dirt or deterioration, otherwise, replace the oil
and filter core if necessary by specialized technicians. Make chemical analysis of the lubricating oil, if
emulsification phenomenon occurs, change the oil of same brand.
Heat exchangers
Adjust the water flow to keep the high/low pressure within normal range (high pressure 0.6~1.2MPa/low
pressure 0.1~0.4,If the temperature difference between leaving cooling water temperature and
refrigerant temperature in condenser is larger than 6 °C, it means the condenser is scaling and