Maintenance Methods for Screw Chiller Units

I. Maintenance Methods for Screw Chiller Units

1. Screw Compressor
   The screw compressor is a crucial component in the unit. The quality of the compressor is directly related to the stability of the unit. If the compressor malfunctions, due to the high installation accuracy requirements of the screw compressor, it is generally necessary to invite the manufacturer for maintenance.
2. Cleaning of Condenser and Evaporator
   The cooling water of the water - cooled condenser is in an open - loop circulation, and tap water is generally used and recycled through the cooling tower. When the content of calcium and magnesium salts in the water is high, they are extremely likely to decompose and deposit on the cooling water pipes to form scale, affecting heat transfer. Excessive scaling can also reduce the cross - sectional area of the cooling water flow, decrease the water volume, and increase the condensing pressure. Therefore, when the quality of the cooling water used is poor, the cooling water pipes should be cleaned at least once a year to remove scale and other dirt in the pipes.

   

   There are usually two methods to clean the condenser water pipes:
   (1) Use a special pipe - cleaning gun to clean the pipes.
   (2) Use a special cleaning agent for circulating flushing, or inject it into the cooling water. Replace the solution after 24 hours until it is clean.
3. Replace Lubricating Oil
   After long - term use of the unit, the quality of the lubricating oil deteriorates, and the impurities and water content in the oil increase.

   

   Therefore, the quality of the oil should be observed and checked regularly. Once a problem is detected, it should be replaced in a timely manner. The brand of the replaced lubricating oil must conform to the technical data.
4. Replace Drying Filter
   The drying filter is an important component to ensure the normal circulation of the refrigerant. Since water and refrigerant are immiscible, if there is water in the system, it will greatly affect the operating efficiency of the unit.

   

   Therefore, it is very important to keep the inside of the system dry. The filter element inside the drying filter must be replaced regularly.
5. Calibration of Safety Valve
   The condenser and evaporator on the screw chiller unit are pressure vessels. According to regulations, a safety valve should be installed on the high - pressure end of the unit, that is, on the condenser body.

   

   Once the unit is in an abnormal working environment, the safety valve can automatically relieve pressure to prevent possible harm to the human body caused by high pressure. Therefore, the regular calibration of the safety valve is of great importance to the safety of the entire unit.
6. Refrigerant Charging
   Under normal circumstances, without other special reasons, the unit will not have a large amount of leakage. If a certain amount of refrigerant leaks due to improper use or after maintenance, it is necessary to recharge the refrigerant. When charging the refrigerant, it is necessary to pay attention to the brand of the refrigerant used in the unit.

II. Operation Management and Precautions for Shutdown

1. Precautions for Operation Management of Screw Chiller Units
   (1) The normal startup and shutdown of the unit must be carried out strictly in accordance with the steps in the operation manual provided by the manufacturer.
   (2) During the operation of the unit, parameter recording should be done in a timely and correct manner.
   (3) If the unit alarms and shuts down during operation, relevant personnel should be notified in a timely manner to check the unit, or you can directly contact the manufacturer.
   (4) During the operation of the unit, it is strictly prohibited to short - circuit the water flow switch to prevent freezing and damaging the water pipes.
   (5) The machine room should be in the charge of special staff. Unrelated personnel are strictly prohibited from entering the machine room and operating the unit.
   (6) The machine room should be equipped with corresponding safety protection equipment and maintenance detection tools, such as pressure gauges, thermometers, etc. The tools should be stored in a fixed location.
2. Precautions for Shutdown of Screw Chiller Units
   (1) After the unit is shut down, the main power switch should be cut off.
   (2) If the unit is in a long - term shutdown state, all the accumulated water in the chilled water and cooling water systems should be drained to prevent corrosion. The water chamber end cover should be sealed.
   (3) During long - term shutdown of the unit, maintenance work should be carried out.
   (4) During the shutdown period, the entire unit should be covered to prevent dust accumulation.
   (5) During the shutdown period, personnel unrelated to the unit should not touch the machine.