How to fill, replace or drain oil in a refrigeration compressor
Before starting any repair work on the compressor, you must read the technical literature or consult with specialists. This is especially important if the device is under warranty . Often, an ordinary oil filling, which takes place in violation of technological moments, inevitably leads to the ingress of air and moisture into the system. To avoid excessive consumption of oil, do not open the container with liquid prematurely. In order to save money, it is better to purchase such an amount that is exactly enough for refueling. Also, do not pour oil from one container to another. See more at How much oil should you add to your compressor?
When pouring used oil from the compressor, use basic protective equipment: goggles and rubber gloves, as the used oil may contain acidic particles.
Most are filled with oil directly at the manufacturer's premises. Exceptions are possible in the case when it is necessary to add oil to the compressor “on site” - this can happen during the installation of the equipment or during its servicing.
Before filling the system with refrigerant, you must first make sure that there is oil, if it is not there, then it is imperative to fill or replace, while the amount of used oil is the same as the one charged. The following equipment is used for refueling: vacuum pump, manometer, charging hose. The entire refueling procedure can be divided into the following stages:
- first, the entire system is evacuated and both service valves on the compressor are closed. A vacuum pump is connected to one of the service valves. Leave the compressor pressure as low as positive, for example 0.1 bar, and stop the pump. Then remove the oil plug and screw on the charging hose with a shut-off valve;
- gradually open the suction service valve, thereby letting refrigerant vapors from the system into the compressor in order to create a slight positive pressure, and then close the suction service valve. Next, a shut-off valve on the charging hose is opened to remove air. After opening the lid in oil, the end of the charging hose is lowered to the very bottom, after which the shut-off valve is closed;
- then the vacuum pump is started and monitored when the pressure in the compressor drops below atmospheric, after which the shut-off valve is opened and oil begins to fill the compressor. In this case, they observe through the viewing window and when the required level is reached, the shut-off valve is closed;
- the vacuum pump is stopped and a slight positive pressure is created by first opening the suction service valve. After that, disconnect the charging hose and screw in the oil plug.
This technique makes sure that neither moisture nor air will enter the system. However, in this case, you can lose a small amount of refrigerant, which will need to be renewed later.When filling the compressor with oil , do not completely empty the oil container, as there is a risk of air getting into the unit . If this does happen, then it is necessary to close the oil plug and perform vacuuming .
In order to reach the maximum oil level, the required amount can be replenished with a syringe. In a short period of time, when the oil plug is open, air will not enter the system and the refrigerant will not quickly evaporate, since it is dissolved in the oil at a pressure higher than atmospheric pressure.
If an oil pump is available, if used correctly, a metered amount of oil can be added to the compressor despite the pressure in the compressor crankcase.
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