How to Read Oil Lab Results for Ammonia Compressors

Routine oil analysis is one of the most valuable tools in maintaining the health, reliability, and efficiency of industrial refrigeration compressors. Understanding how to interpret ammonia compressor oil lab results allows operators, technicians, and management to make informed decisions about oil changes, contamination control, and early detection of mechanical issues.

When interpreting ammonia compressor oil lab results, knowing the compressor manufacturers general guidelines for acceptable ranges of viscosity, wear metals, water content, acidity, and other parameters is the best baseline to start with. The following sections break down the most common data points you’ll see on an oil analysis report and what they mean for your ammonia refrigeration system.

Lube Hours

This value indicates the number of hours the lubricant has remained in the compressor since the last oil change. By comparing the lube hours with the oil's physical condition, you can gauge how much longer the oil will remain effective.

• Typical expectation: Many plants aim for about 6,000 hours between oil changes.

• The actual interval may vary depending on contamination, operating conditions, and oil type.

  
  

Viscosity

Viscosity is one of the most critical indicators of oil health. For optimum lubrication, the oil must maintain the manufacturer-specified viscosity range.

• Acceptable range: 55.8–78 cSt @ 40°C

• If viscosity increases:

  • Possible ammonia contamination

  • Other foreign substances in the oil

  • Excessively high discharge pressures

  • High suction superheat

• If viscosity decreases:

  • Oil dilution by mineral oils, solvents, or other chemicals

  • Loss of lubrication capability

Maintaining the correct viscosity ensures the oil can properly seal, cool, and lubricate compressor components.

T.A.N. – Total Acid Number

Every lubricant has a baseline acidity level based on its formulation. TAN measures the level of acidic compounds formed due to oxidation and degradation.

• Normal range: 0.001–0.99

• A TAN increase of more than 1.0 above the baseline indicates oxidation is occurring. Oxidation destroys lubricity, breaks down additive packages, and accelerates wear. Monitoring TAN helps identify when the oil is beginning to fail chemically.

Filtration Time

Contamination, overheating, and oxidation all lead to suspended particles in the oil. Filtration time measures how long it takes for the oil to pass through a standardized filter.

• Normal range: 1.5–10 minutes

• Over 10 minutes:

  • Indicates excessive contamination

  • Oil filter may be bypassing internally

  • Contaminated oil may be circulating through the compressor

  • Oil filter replacement is recommended

A longer filtration time is often one of the earliest indicators of developing mechanical or oil-related issues.

Appearance

Visual inspection still matters. Any significant change from the oil’s original color may indicate contamination or chemical changes within the lubricant.

• Darkening or cloudiness often correlates with oxidation, moisture, or sludge.

• Appearance alone won’t pinpoint the issue, but it often supports other findings in the report.

  
  

Anti-Oxidant Levels

Lubricants are formulated with anti-oxidant additives that prevent oil thickening and protect compressor components from corrosion.

• New oil: 100% additive strength

• When anti-oxidants fall to 5%: Oil should be replaced

• Low anti-oxidant levels lead to rapid oxidation and a shorter remaining oil life

  
  

Special thanks to CAMCO for providing the research data that made this information possible to share.

Lube Hours and CAMCO 717-HT

CAMCO 717-HT lubricant is known for exceptional longevity, often lasting up to 20,000 hours under ideal conditions. However, older refrigeration systems commonly contain sludge, tar, or varnish buildup. As these deposits gradually break loose, they contaminate the new oil faster than expected.

• Systems with heavy buildup may take up to two years to fully clean out.

• Cleaner systems experience fewer maintenance issues and more stable oil life.

• Periodic oil sampling allows early detection of any abnormal changes.

  
  

Final Thoughts

Regular oil analysis is not just a maintenance task, it’s a predictive tool that protects compressors from premature wear, contamination, and mechanical failure. By monitoring viscosity, TAN, filtration time, additive levels, and overall appearance, operators can extend oil life, improve system reliability, and reduce costly downtime. A well-interpreted laboratory report provides clear insight into the condition of both the oil and the compressor itself. When any parameter exceeds recommended limits, prompt corrective action ensures long-term system health and smoother plant operations.

Stay tuned to the MySafety blogs. Reach out to us if you have additional questions or concerns. Our team will be pleased to assist you.

Our community can't grow without you, and we deeply appreciate your support.

Please LIKE, SHARE, and FOLLOW our content on social media platforms.

Join our newsletter mailing list to stay up to date on our latest blogs/articles and information.

KEEP IT COOL & SAFE!

Ammonia Compressor Oil Analysis