Why is the return oil white in color?
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In our centrifugal compressor units, the oil return pipe is connected to both the oil return port and the coupling; the color of the oil in the oil return sight glass is white, which is different from the color of the oil in other return lines. Why is that?
Take a little of the oil and check whether it contains water or any gases, as well as what color it takes when mixed with the oil
Inlet water, emulsification; it is recommended to check for leaks in the oil cooler
It’s just a difference in temperature; don’t worry
There is internal water ingress, caused by oil emulsification.
In centrifugal compression units, high rotational speeds require the use of oil-lubricated bearings, which facilitate heat dissipation and rapid startup. Question: Oil emulsification – After emulsification, the mixture generally takes on a milky white color similar to that of milk. Since water cannot act as a lubricant, bearing wear increases. Emulsions, with increased viscosity, reduce circulation speed, which is detrimental to heat dissipation. Solve ； 1. Check for leaks in the oil cooler; the seals may not be resistant to oil. 2. If the lubricant has poor anti-emulsification properties, a lubricant that is resistant to water can be chosen.
To determine if the oil is turning white, one usually checks whether there is any white residue on the oil sight glass. If the sight glass is clear, it is generally caused by bubbles in the oil; however, if there are white solids on the sight glass, the situation is more serious. Regularly, it is necessary to strengthen the inspection of the quality of lubricating oil.
Sometimes it is not a problem with the quality of the oil that causes the return oil to turn white. As mentioned above, bubbles in the oil can also cause the returning oil to turn white; it is necessary to conduct an oil analysis to determine exactly what the problem is.
If only the coupling is milky white, it’s likely a bubble issue; emulsification is unlikely to be the cause.
If the oil is emulsified, water droplets or mist will form above the oil sight glass.