First, the role of lubricating oil:
1) A dynamic seal is formed between the screw, the compression chamber and the male and female screws to reduce the leakage of refrigerant from the high pressure side to the low pressure side during the compression process.
2) To cool the compressed refrigerant, oil is injected into the compressor to absorb the heat generated by the refrigerant gas during the compression process and reduce the exhaust temperature.
3) An oil film is formed between the bearing and the screw to support the rotor and lubricate it.
4) It transmits the differential pressure force, drives the capacity adjustment system, and adjusts the position of the capacity adjustment slider through the action of the loading and unloading solenoid valve of the compressor to realize the capacity adjustment control of the compressor.
5) Reduce running noise
illustrate:
The lubricating oil inside the compressor is the key to maintaining the normal operation of the compressor. The general problems of lubricating oil are:
1) Foreign matter is mixed in, causing lubricating oil pollution and blocking the oil filter.
2) The high temperature effect causes the deterioration of the lubricating oil and the loss of the lubricating function.
3) Water pollution, acidification and erosion of the motor in the system.
2. Compressor refrigeration oil inspection and replacement:
For system manufacturers, the detection and replacement cycle of compressor refrigeration oil is related to the process control of its production process. If the cleanliness of the system’s evaporator, condenser and system pipeline is well controlled, the pollutants entering the compressor will be relatively less, and the inspection and maintenance period can be relatively extended.
Main monitoring indicators:
1) PH value index: The acidification of the lubricating oil will directly affect the life of the compressor motor, so it is necessary to regularly check whether the acidity of the lubricating oil is qualified. Generally, the acidity of lubricating oil is lower than PH6 and needs to be replaced. If the acidity cannot be checked, the filter drier of the system should be replaced regularly to keep the dryness of the system in a normal state.
2) Pollution degree index: If the pollutants in 100ml of refrigeration oil exceed 5mg, it is recommended to replace the refrigeration oil.
3) Water content: more than 100ppm, the refrigeration oil needs to be replaced.
Replacing cycle:
Generally, the lubricating oil must be checked or replaced every 10,000 hours of operation, and after the first operation, it is recommended to replace the lubricating oil and clean the oil filter every 2,500 hours. Residues due to system assembly will accumulate in the compressor after the actual operation. Therefore, the lubricating oil should be replaced every 2,500 hours (or 3 months), and then periodically according to the cleanliness of the system. If the system cleanliness is good, it can be replaced every 10,000 hours (or every year).
If the exhaust temperature of the compressor is maintained at a high temperature for a long time, the deterioration of the lubricating oil will progress rapidly, and the chemical characteristics of the lubricating oil must be checked regularly (every 2 months), and replaced if it is unqualified. If regular inspection is not possible, it can be carried out according to the following recommendation table.
3. Operation method of refrigeration oil replacement:
1) Replacing the refrigeration oil without internal cleaning:
The compressor performs the pumping action to recover the refrigerant of the system to the condenser side (note that the minimum suction pressure of the pumping action is not less than 0.5Kg/cm2G), remove the refrigerant in the compressor, retain a little internal pressure as the power source, and put the refrigeration Oil is drained from the oil drain angle valve of the compressor.
2) Replace the refrigeration oil and clean the interior:
The oil draining action is as described above. After the refrigeration oil is drained clean and the pressure inside and outside the compressor is balanced, loosen the flange bolts with an Allen wrench, and remove the oil filter joint and the flange of the clearing hole (or oil level switch flange). After cleaning, remove the pollutants in the oil tank of the compressor, check whether the oil filter mesh is damaged, and blow off the sludge, pollutants, etc. on it, or replace the oil filter with a new one. The filter interface nut should be tightened and sealed to prevent internal leakage; the inner gasket of the oil filter joint must be replaced with a new one to prevent internal leakage; other flange gaskets are also recommended to be updated.
Four notes:
1. Different brands of refrigeration oil must not be mixed, especially mineral oil and synthetic ester oil must not be mixed.
2. If you replace the refrigeration oil of a different brand, be careful to remove the original refrigeration oil remaining in the system.
3. Some oils have hygroscopic properties, so do not expose the refrigerated oil to the air for a long time. When installing, minimize exposure time and do a good job of vacuuming.
4. If the compressor motor has been burned out in the system, special attention should be paid to removing the remaining acidic substances in the system when replacing the new machine, and the acidity of the refrigeration oil should be checked after 72 hours of commissioning and operation. It is recommended to replace the refrigeration oil and drying filter. , reduce the possibility of acid corrosion. After running for about a month, check or replace the refrigeration oil again.
5. If there has been a water intrusion accident in the system, special attention should be paid to removing the water. In addition to replacing the refrigeration oil, special attention should be paid to detecting the acidity of the oil, and replacing the new oil and drying filter in time.
Post time: Mar-16-2022
