Novel Varnishing Potential Analysis Developed for Gas Turbine and Hydraulic Systems Prevents Unexpected Equipment Failure

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The lubricating oil in gas turbines and hydraulic systems is increasingly subject to the ravages of varnish. The debilitating effects of varnish are well documented. The complexities associated with detecting varnish potential render routine oil analysis ineffective in reporting varnish. However, there are a number of technologies, although seldom used, which have been successful in reporting incipient varnish potential. Insight Services has developed a Varnishing Potential Analysis that incorporates these technologies into one simple report to offer an integrated varnish potential solution.

Whether you are tending to a gas turbine or a large hydraulic system, the mere mention of varnish can cause your spine to tingle. A number of explanations for the increasing occurrence of lube oil varnish have been postulated. Tighter filtration requirements, higher lube oil flow rates, higher operating temperatures, and the switch to Group II base stocks in oil formulations have been offered as potential culprits in the decimation of many lube oil systems. The destruction left in the pathway of varnish can often lead to unplanned outages and costly downtime. Understanding and responding to varnish with remedial filtration is critical. Unfortunately, the ability to measure varnish potential has remained elusive.

Insight Services, an industrial oil analysis lab with headquarters in Cleveland, Ohio, has developed a Varnishing Potential Analysis solution to alert customers of developing lube oil varnish potential. Their new analysis combines multiple testing technologies to measure a lube oil’s propensity to drop out varnish deposits.

Insight’s new “Varnishing Potential Analysis” combines the results of seven individual tests to provide a complete analysis of a lube oil’s varnishing potential. The ultra centrifuge test subjects a lube sample to significant G-forces which yields oil degraded insoluble contaminants typically associated with varnish. The density of the agglomerated material is compared to a rating scale to derive a UC Value. Microscopic Particle Counting is used as a tool to trend particles in the microscopic size ranges and alert of potential varnish anomalies. It is well documented that varnish is a thin insoluble contaminant comprised of oil degradation by-products and sometimes depleted additive molecules. Because these “soft contaminants” are less than 1 micron in size, this technique allows a technician to visually count particles with a high intensity microscope and monitor the submicron ranges for increases in levels.

Mike Barrett, Insight Services’ Director of Marketing, explains the benefit: “Initially we thought the colorimetric analysis was an adequate solution. As we dug deeper, it became apparent that the ultra centrifuge test and microscopic particle counting are just as valuable in determining varnishing potential.”

As more operators face the prospects of varnish in their lube oil systems, they are turning to oil analysis labs for answers. But the unique nature of varnish particles makes detection extremely difficult. The standard battery of oil analysis tests proves futile. The new Varnishing Potential Analysis developed by Insight services offers a solution to detecting your lube oil’s propensity for varnish. Once aware of varnish potential, you can take active measures before the destructive varnish ravages your system. Visit Insight Services at to find out additional information on Varnishing Potential Analysis.


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