Brief Analysis on Causes of Varnish Formation in Air Compressor Lubricating Oil

Lubricating oil acts as the "blood" circulating inside an air compressor. Normal operation of air compressors relies heavily on lubricating oil. 

Varnish formation will seriously impair the efficient operation of air compressors. This article conducts an in-depth analysis of the causes behind varnish formation in air compressor lubricating oil.

1. Metal Ions

   During compressor operation, friction between components readily generates metal debris. Such metal debris serves as a catalyst, 

2. accelerating chemical reactions of certain hydrocarbon polymers inside the lubricating oil. In addition, metal ions may block the oil circuit system of the air compressor and trigger varnish formation.

3. Oxidation

   The lubricating oil inside air compressors generally operates at elevated temperatures. High temperatures easily initiate oxidation reactions of the oil. Over time, 

4. polymeric sediments are formed, leading to varnish build-up. Higher oxygen concentration intensifies oxidation, shortening the service life of lubricating oil.

5. Influence of Moisture

   Water vapor from ambient air enters the compressor and contacts the lubricating oil, resulting in oil emulsification and white flocculent substances. Emulsified oil is more susceptible to hydrolysis, 

6. triggering rust formation inside the compressor. The resulting iron debris further promotes varnish formation in lubricating oil.

7. Impact of Used Oil

   Matching dedicated lubricating oil must be adopted for air compressors. Two different types of lubricating oil cannot be mixed. Lubricants manufactured by different suppliers adopt different additive packages; 

8. mixing different oils may cause chemical reactions between incompatible additives. Moreover, residual old lubricating oil can cause deterioration of new oil and lead to varnish formation.