Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/229047
LESSONS IN LUBRICATION then established to help determine any significant reduction in specific additives. Another section of the oil analysis report presents previously identified sample information from the customer such as oil manufacturer, brand, viscosity grade and in-service time, as well as if an oil change has been performed. This is important data that can provide an explanation for what could be false positives in alarming data changes. The "physical tests" section of a report offers details on viscosity at both 40 degrees C and 100 degrees C, along with the viscosity index and percentage of water. For common industrial oils, the viscosity measurement at 40 degrees C is usually given, since this correlates to the oil's ISO viscosity grade. If the viscosity index must also be calculated, such as for engine oil, then these additional viscosity measurements will be identified. The viscosity for engine crankcase oils is typically reported at 100 degrees C. Water contamination, which commonly is measured by the Karl Fischer test, is presented in percentages or ppm. While some systems are expected to have high levels of water (more than 10,000 ppm or 10 percent), the typical alarm limits for most equipment are between 50 to 300 ppm. The "additional tests" section shows two final tests: acid number (AN) and particle size distribution (aka, particle count). When analyzing the acid number, you should have both a reference value and the ability to trend from past analysis. The acid number often will jump considerably at some point. This may be your best indicator for when the oil is oxidizing rapidly and should be changed. The last section of the oil analysis report generally provides written results for each of the final few test samples along with recommendations for required actions. Typically, these recommendations are entered manually by laboratory personnel and based on information provided by the customer and the data collected in the lab. If there is an explanation for the data that stems from something not explicitly stated by the customer, the results must be reinterpreted by those familiar with the machine's history of environmental and operating conditions. Understanding the information given here is critical. Remember, there is always an explanation for each exceeded limit, and the root cause should be investigated. In addition to the raw data shown throughout the oil analysis report, graphs can help illustrate notable trends in the data. Below is an example of trended data points from analyzed data, with the water test having the most notable unfavorable spike. Along with the trend data, graphs should show typical averages, warning (marginal) limits and alarm (critical) limits. These limits Graphs in an oil analysis report can help illustrate notable trends in the data. (Ref. Fluid Life) 50 | November - December 2013 | www.machinerylubrication.com