Knowing the knowledge of special oil for air compressor will make the life of air compressor longer!

Author : RUNNINGWAY

Update time : 2020-05-27 13:50:48

In air compressor refrigeration, oil and refrigerant are constantly mixed. Air compressor oil is soluble in liquid refrigerant, and they can be completely mixed at normal temperature. Since oil must pass through the compressor block to provide lubrication, a small amount of oil always circulates with the refrigerant. Oil and refrigerant vapors are not easy to mix. Only when the gas velocity is high enough to sweep the oil can the oil be properly circulated through the system.

If the refrigerant speed is not high enough, the oil will tend to be located at the bottom of the evaporator piping, reducing heat transfer and may cause insufficient oil in the compressor. As the evaporation temperature decreases, this problem becomes more critical because the viscosity of the oil increases as the temperature decreases. For these reasons, proper piping design is essential for satisfactory oil return in refrigeration systems.

One of the basic characteristics of a refrigerant-oil mixture in a sealed system is that the refrigerant is attracted by the oil and will evaporate and migrate through the system to the compressor even if there is no measurable pressure difference resulting in movement. Upon reaching the compressor, the refrigerant will condense into a liquid. This migration will continue until the oil is saturated with liquid refrigerant. The amount of refrigerant that oil will attract depends mainly on the temperature, which increases rapidly with increasing temperature and approaches the maximum value at normal room temperature.

When the pressure on the saturated mixture of refrigerant and oil suddenly decreases, as occurs in the compressor at start-up, the amount of liquid refrigerant required to saturate the oil decreases sharply, and the remaining liquid refrigerant flashes into steam, A mixture of refrigerant and oil that causes violent boiling.

This results in typical foaming often being observed in the compressor at startup, which can remove all the oil from the compressor in less than a minute. In the first encounter with service personnel, one of the surprising conditions is that although the level of refrigerant and oil mixture may cause too much liquid refrigerant to be introduced into the compressor, the oil pressure or The loss of oil transported to the bearing is observed in the sight glass.

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