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Analysis of Lubricant Coking Causes in Air Compressors

Analysis of Lubricant Coking Causes in Air Compressors


Air compressor lubricating oil is continuously affected by high temperature, oxygen, pressure, and metal catalytic effects during operation. 

Over time, the oil undergoes oxidation and degradation, leading to sludge, carbon deposits, and eventually coking.


Oil Oxidation Is the Main Cause of Coking


The main components of lubricating oil are hydrocarbon compounds, including:

  • Paraffins

  • Naphthenes

  • Aromatics

During compressor operation, continuous exposure to high temperature and oxygen causes oxidation reactions.

These oxidation reactions can cause:

  • Molecular chain breaking

  • Molecular cross-linking

  • Increased oil viscosity

  • Higher acid value

  • Darkened oil color

  • Increased insoluble deposits

When oxidation becomes severe, deposits harden and form carbon-like substances, resulting in lubricant coking.

Main Factors Causing Lubricant Coking

1. Poor Quality LubricantLow-quality mineral oils usually have:

  • Poor oxidation resistance

  • Weak high-temperature stability

  • Short service life

They are more likely to oxidize and form carbon deposits under high-temperature compressor conditions.

 Long-Term High Temperature Operation


High operating temperatures caused by:

  • Poor cooling performance

  • High ambient temperature

  • Blocked coolers

  • Excessive oil temperature

will accelerate oil oxidation and increase coking risks.


How to Prevent Lubricant Coking


Use high-quality compressor lubricants

Maintain proper operating temperature

Inspect cooling systems regularly

Replace oil and filters according to maintenance schedules

Avoid long-term overload operation


The main cause of air compressor lubricant coking is oxidative degradation under high-temperature and oxygen-rich conditions

Using high-quality lubricants and maintaining proper operating temperatures are essential to ensure stable compressor performance and extend service life.



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