Refrigerant oil replacement method and steps

Different compressors have different methods for replacing refrigerant oil. This article takes screw compressors as an example.
Method for replacing refrigerant oil in screw compressors:

1. Recover the system refrigerant to the condenser side, remove the refrigerant in the compressor, and discharge the refrigerant oil from the oil drain angle valve of the compressor.
2. The lubricating oil of the compressor is discharged from the oil drain valve on the oil filter. When the lubricating oil is almost exhausted, add a certain amount of nitrogen from the high-pressure end detection joint of the compressor, use pressure to accelerate the discharge of the lubricating oil, stop injecting pressure, and close the oil drain valve. Then remove the oil filter of the compressor, drain all the lubricating oil in the oil tank, and then clean the oil filter and install it to tighten it.
3. Add lubricating oil according to the standard amount of the compressor, and evacuate the system at the same time. It is recommended to select the high (low) pressure side angle valve or other relatively high points for the vacuum pump contact to prevent the vacuum pump from being damaged by the refrigerant oil. When performing vacuum pressure maintenance or leak detection, observe whether the pressure rebounds.
4. Inject lubricating oil, connect the clean plastic tube to the oil drain valve, and put the other end of the plastic tube into the oil barrel (the plastic tube is placed at the bottom of the oil barrel). The oil barrel should be sealed when injecting oil to reduce air pollution to the oil.