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Flooded type water cooled screw chiller (MIC)
MCAC-CTSM-2018-1
90
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
between the condensing temperature and leaving cooling water temperature may become bigger. It
means that the cooling water is dirty or the water is hard, and it is scaling constantly. So it is compulsory
to perform a softening process or clean the tubes.
Note: Keeping the normal operation parameters of the initial unit
’s commissioning is very useful. It can
be used for comparative analysis to find out problem trends.
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 is with in the allowable range. Check whether the power supply is within ±10% of
the rated voltage at any time.
Visual inspection
Keep the unit clean. If there is rust, do scaling with iron brush and cover it with antirust paint. Pay
attention to oil traces (sign of a refrigerant leak) and water traces on pipeline. Check the threaded
connection joints carefully, fasten any loose screws in time. If the insulating material flakes off, stick it
with adhesive.
Compressor
Check insulation resistance yearly. It should be over 5
MΩ when measuring with a DC 500V ohmmeter .
When touching the shockproof rubber, it should be elastic, or the rubber will age. Every 3,000 hours,
inspect vibration and oil. Every 6,000 hours, check the safety device and protective device to guarantee
normal operations.
Important: The normal oil level is in the middle of sight glass. Add lubricating oil if the oil level declines
noticeably. Inspect the oil quality monthly to see if there is dirt or deterioration. 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 with the same brand.
Heat exchangers
Adjust the water flow to keep the high/low pressure within a normal range (high pressure
0.6~1.2MPa/low pressure 0.1~0.4),If the temperature difference between the leaving cooling water
temperature and refrigerant temperature in the condenser is more than 6 °C, the condenser is scaling
and cleaning is needed. When the chiller is not used for a long time, fully drain the water in heat
exchangers and pipe system. For newly installed chiller, the filters in water system should be cleaned
after running for 24 hours and then clean the filters quarterly.
Valves and pressure controllers
▲ Safety valves
Inspect the integrity and performance of valves every year. Maintenance ON safety valves should be
performed by specialized technicians. Take apart the connecting pipe of the safety valve, and check it to