Machinery Lubrication magazine published by Noria Corporation
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42 | July - August 2017 | www.machinerylubrication.com IN THE TRENCHES individuals in the field. However, if the lab made a mistake and reported a fluid prop- erty, wear or contamination parameter in a critical or red state, immediate action was taken, which normally meant dumping the oil charge and replacing the filters without ever taking a follow-up sample to confirm the evidence of an issue. If even one of those red reports had been a false positive, you could have avoided several man-hours of work and in some cases thousands of dollars in replacement parts. This could have easily paid for the secondary sample or follow-up action required to ensure the lab results were accurate. When you receive less than desirable oil analysis results, the first step generally is to take a follow-up or confirming sample to send to the laboratory for more testing. Although this is an easy process to imple- ment, it requires diligence on the part of the individual reviewing the data as well as the person taking the sample. If the orig- inal sample comes back in a critical alarm, taking another sample and sending it to the lab for immediate analysis must be pushed to the top of the priority list. This works well for most organizations that are willing to rely on the lab to have its own standards and policies for ensuring repeat- ability of the tests. Others would rather take this into their own hands and be the masters of their own data. Onsite Oil Analysis With many manufacturers of laboratory instruments now offering smaller and easier- to-use equipment for field applica- tions, onsite oil analysis is becoming increasingly popular. These devices can perform a vast array of tests on used oil and provide useful data in nearly real time. Of course, the same consistency concerns that commercial laboratories must overcome also apply to onsite labs. These issues can be even more difficult for onsite laborato- ries due to the training and calibration requirements of much of the equipment. Still, these are fantastic tools for any oil analysis program. Far too often when auditing lubrication programs, I see companies that have invested in testing equipment but do not properly maintain it or dedicate adequate personnel for its upkeep and use. Even for those who do make the proper investment in equipment and staff, the onsite lab should never replace sending periodic samples to an outside commercial labora- tory. In most cases, the commercial lab will be able to perform more specialized tests than the onsite lab and can serve as a crucial check of your internal testing proto- cols and equipment accuracy. Checking a Lab's Accuracy One way to check the accuracy of any oil analysis laboratory is by using what is commonly referred to as a tracer sample. Think of this as a blind test to determine whether your sample preparation and results are what they should be. You can use the same fluid in multiple samples or change the fluid to see what the results will be. The best practice is to utilize a reference sample of new oil, which you can then use to check for signs of additive depletion, viscosity changes or other physical property differences. Instead of extracting a single sample of new oil, you could take several. This will provide a bank of oil samples from the same batch of new oil. These now become your tracer samples. Send the first tracer sample to the lab and have it tested against the normal test slate. The results should be archived. Several months later, send another tracer to the lab for analysis. Remember, oil ages, even inside a sample bottle, but the change is very slight. Therefore, the results of the additional tests should be in the same range. If the results vary widely, there is an issue with either the testing equipment or in the sample preparation. Ultimately, it will be up to the laboratory to determine the reason, but this merits a phone call to discuss the results. This process is equally effective for onsite labs. Just be sure they don't know when a tracer sample is coming. To check the accuracy of specific tests, such as elemental analysis or particle counting, you might choose to employ different fluids. For example, an ultra-clean lamp oil could be used to test a particle counter. If a sample of this type of oil is sent for particle counting, the results should be very low. If high particle counts are seen, it could be an indication that something is not working properly. Turbine oil can be used for checking elemental analysis. Most oil analysis results for turbine oils appear as a blank slate in the elemental signature. Sending a sample of a known turbine oil and then analyzing the results in the elemental spectrum can provide good information on the repeat- ability and accuracy of a lab. Some companies prefer to use multiple commercial laboratories to test the same sample of oil and then compare the results. This is quite common and encouraged for the utmost data accuracy. While this may not be feasible for every oil sample, it is good practice to periodically send the same sample from a critical machine to two different labs and run the same test slate just to ensure your data is trustworthy. 25% of lubrication professionals say they would not under- stand how to interpret an oil analysis report received from a commercial laboratory, based on a recent survey at MachineryLubrication.com