Hitachi SAMURAI CLG2, Руководство пользователя, Страница: 73 / 118

Maintenance
Technical Catalogue
11
73
TCGB0051 rev 0 - 09/2009
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CAUTION:
- Do not charge OXYGEN, ACETYLENE or other flammable and poisonous gases into the refrigeration cycle
when performing a leakage test or an airtight test. These types of gases are extremely dangerous, because
explosion can occur. It is recommended that compressed air or nitrogen be charged for these types of tests.
- Mineral deposits on water cooler plates act as thermal insulators, and also act as resistance Against water flow,
causing the water flow to decrease running through them, and resulting in a decreasing of the cooling capacity.
Deposits on the plates should be inspected at regular, intervals, experience with the water Chiller will dictate
accurate inspection intervals.
- These deposits should be removed by circulating diluted acid through the water passes after the water has
been drained. As water in different localities contains different minerals, different acids are required, depending
upon the thickness of the deposits.
- This unit is equipped with an operation hour meter. In the case that the total operation time reaches 40,000
(water-cooled) hours or 5 years. and 24,000 (air-cooled) hours or 3 years pass after installation, exchange the
bearings of the compressor. For details, refer to the Service Handbook for HITACHI Screw Compressors.
- For R407C refrigerant system, charge the refrigerant with liquid condition to avoid its composition change.
11.10. Compressor removal
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When Removing the Compressor
Remove the compressor while completing the following procedures.
1. Collect all refrigerant into a condenser before this work.
2. Turn off the switch, DSW3 of the PCB in the electrical box in order not to operate the compressor except
for the cycle.
3. Circulate the chilled and cooling water sufficiently through the water cooler and condenser, and operate
the water Chiller for 10 minutes, and check to ensure that the oil level is maintained at a stable condition.
4. Stop the Chiller and completely close the liquid stop valve.
5. Operate the Chiller after circulating water through the water cooler and field supplied condenser.
6. Stop the Chiller when the low pressure reaches at approximately 0.05 MPa. Do not operate at the
pressure lower than 0.05 MPa. If operated, it will cause a damages to the compressor.
7. Wait for several minutes. If the low pressure increase up to 0.15 to 0.2 MPa, repeat the above
procedures 5 and 6 four or five times.
8. Turn OFF the power supply to the unit.
9. Remove the bolts on the discharge and suction flanges of the compressor.
11.11. Safety and protection control
The safety and protective devices are equipped with the unit to ensure dependable and long life operation.
Their functions should be carefully noted, and field adjustment is not recommended, if the setting is
maintained at the point listed in the table
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Compressor protection
1. Fuse and thermal relay equipped in the control box cut out each compressor operation when the current
to the compressor exceeds the setting
2. The internal thermostat embedded in the motor winding cuts out each operation, when the temperature
exceeds the setting
3. The oil heater in the compressor prevents from oil foaming during cold starting. This heater warms the
oil, while the compressor is stopped
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Refrigeration Cycle
1. The high pressure switch and low pressure control protect against excessive discharge pressure and
exceedingly low suction pressure. The switch and control cut out compressor operation when discharge
pressure or suction pressure is abnormal.
2. The pressure relief field supplied valve is equipped on discharge gas line. When high pressure exceeds
the setting, gas refrigerant will be discharged to prevent abnormal high pressure
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Water Cooler
Pump interlock, freeze protection control, low pressure control and suction gas temperature control can
protect water cooler against water cooler freezing