Maintenance methods for refrigeration units-Shenzhen Oukelong Technology Industrial Co., Ltd

Maintenance methods for refrigeration units
1、 Compressor:

1. Oil change: The unit must change the refrigeration oil once a year, or decide whether to change the oil in advance based on the actual situation or oil analysis conclusions.

2. Oil filter replacement: Replace the oil filter when the oil pressure drops by 30% or after the unit has been running for six months. At the same time, check for metal shavings in the filter to confirm the wear condition inside the unit.

3. Tighten the slide valve: Check and tighten the pipeline connection of the slide valve.

4. Check the coil: Check the solenoid valve coil of the slide valve.

5. Check the compressor motor:

① Check the insulation of the motor;

② Add lubricating grease or oil to the motor bearings;

③ Check the contacts of the motor starter;

④ Check the contactor of the motor starter.

Maintenance methods for refrigeration units

2、 Return oil system:

1. Replace the dry filter of the return oil system.

2. Clean the nozzle of the oil injector.

3. Clean the accumulated material in the settling elbow.

4. Check that the solenoid valve of the injection circuit is functioning properly.

5. Check that the connecting pipelines of the entire oil return system are unobstructed.

Maintenance methods for refrigeration units

3、 Evaporator and condenser:

1. Check the flow of chilled water and cooling water.

2. Check the flow switches of chilled water and cooling water.

3. Check the refrigerant charging amount.

4. Check the screws of the evaporator and condenser water chambers and end caps. Confirm that there is no water leakage.

Maintenance methods for refrigeration units

4、 Check the refrigerant charging amount:

After the unit is stopped, the refrigerant charging amount should be checked and adjusted.

After the compressor and water pump have been shut down for four hours or more, the pressure and temperature of the condenser and evaporator reach equilibrium. At this point, the refrigerant level should be visible through the sight glass.

3. Keep a record of the refrigerant level. And compare with the original records to determine the sealing condition of the unit.

Maintenance methods for refrigeration units

5、 Startup cabinet:

1. Check and confirm the overload protection setting value of the air switch.

2. Clean the dust accumulated inside the starter cabinet.

3. Check the wiring of the starter cabinet and tighten it.

4. Check the contactor and its contacts.

5. Start the empty action test of the cabinet.

Maintenance methods for refrigeration units

6、 System leak detection:

1. The refrigerant side of the unit has undergone strict leak detection procedures both in the factory and during the commissioning process.

After the operation of the unit, the high-pressure part should be checked again with a leak detector to ensure the sealing of all connections.

If any leaks are found, they should be dealt with immediately. In general, tightening the connecting pins or flange bolts can eliminate the leakage point, but there is also a possibility that the refrigerant must be recovered and the leakage point must be treated. For example, leakage at the welding seam.

Maintenance methods for refrigeration units

7、 System pressure leak detection:

1. Fill the system with nitrogen until it reaches 25-50PSIG. Ensure that pressure reaches all parts of the system. You can slightly open the oil injection valve and use a leak detector to check for refrigerant.

2. Check every joint and weld seam carefully and take as much time as possible. The leak detection equipment used must be sensitive and reliable.

3. Open the top vent valves of the evaporator and condenser, and confirm that no refrigerant is detected. If refrigerant is found, the end cap should be removed to eliminate internal leakage.

4. Confirm that the system is completely sealed, and release gas from the filling valve at an appropriate flow rate to provide a certain purging effect.

Maintenance methods for refrigeration units

8、 Vacuum extraction and drying of the system:

1. Connect the high-efficiency vacuum pump and mercury vacuum gauge in series with the filling valve of the system.

2. Open all connected valves, exhaust valves, and vacuum gauges in the system. Confirm that all atmospheric valves are closed.

3. Start the vacuum pump and draw the vacuum degree of the system to 5mmHg.

If conditions permit, hot water at 50 º C can be introduced into the system to accelerate the evaporation of the liquid stored in the system and improve dryness.

5. Maintain the vacuum degree for 8 hours. If the vacuum degree rises to no more than 6.3mmHg, the vacuum degree test is considered qualified.

If the vacuum degree rises beyond the standard, the leak detection work must be repeated.

Maintenance methods for refrigeration units

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