7. MAINTENANCE
101
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CAUTION
To prevent severe scale attachment or to remove the scale, conduct a chemical treatment, but for a proper treatment, con-
sult a water treatment specialist.
Heat exchanger tube cleaning (evaporator/condenser)
Heat exchanger tube inspection
- Evaporator
When the first operation season is over, clean the evaporator tubes. These tubes having foreign objects inside, to
completely clean the tubes, a special caution is required. The tube condition at this time will be the data to decide
how often tube needs to be cleaned and whether water handling in the chilled water(brine) system is appropriate.
Check the corrosion or scale in the chilled water inlet/outlet temperature sensor, and if there is a corrosion, replace
the sensor, and if there is a scale, remove the scale.
- Condenser
Since cooling water circuitry is generally of an open system, the tubes are easily contaminated and scale is easily
accumulated. Therefore, condenser tubes need to be cleaned at least once a year, and if the water is contaminated,
should be cleaned more frequently.
Check the corrosion or scale in the cooling water inlet/outlet temperature sensors, and if there is a corrosion, re-
place the sensor, and if there is a scale, remove the scale.
The reason that the condenser pressure is higher than normal but not reaching previous chilling load is generally be-
cause tubes are contaminated or there is air in the machine.
If the difference between cooling water outlet temperature and condenser refrigerant temperature is big, condenser
tube may be contaminated or water flow is not in good condition.
Since the refrigerant is used in a high pressure, it is easier to have leakage than to have air inside.
When cleaning the tube, use a specially designed brush not to scratch the tube wall. Never use wire brush.
- Refrigerant charging amount adjustment
To enhance the performance of the machine, in case it is required to adjust the refrigerant charging amount, run the
machine at the designed load, and slowly add or remove refrigerant until the difference between the chilled water
outlet temperature and the evaporator refrigerant temperature becomes the designed value or the minimum. Do not
overcharge the refrigerant.
Refrigerant may be added through storage tank or directly charged to the chiller.
- Refrigerant leakage inspection
Since the refrigerant has a higher pressure than the air pressure at room temperature, leakage inspection is neces-
sary. Carry out the leakage inspection using electronic detector, or halogen leakage detector, or soap bubbles.
Room ventilating should be adequate, and to prevent wrong measurement, check whether the refrigerant is gath-
ered in one place. Before performing any repair work on leakage, remove all of the refrigerant from the leaked con-
tainer.
- Refrigerant leakage
If there are many refrigerant leakage and chiller performance is greatly degraded, thus its operation becomes impos-
sible, it is advised to stop using the chiller and perform repair work.
- Refrigerant filter
Refrigerant filter/drier installed in the refrigerant cooling pipe of the motor needs to be replaced once a year. It may
require more frequent replacement depending on the filter condition.
To find the existence of moisture in the refrigerant, a sight glass is installed next to the filter.
If you see moisture through the sight glass, conduct a thorough leakage inspection to find the source of the water.
ENGLISH
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