Machinery Lubrication

Machinery Lubrication May June 2014

Machinery Lubrication magazine published by Noria Corporation

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Page 51 of 77 | May - June 2014 | 45 particles produced will be among the most important properties of the oil. Because several components are being lubricated, the "live zone" for sampling is in more than one location. This requires a sample to be taken after the lines converge on the return lines but before being passed through a return-line filter and back to the reservoir (in the case of a hydraulic system). This sampling location provides a good representative oil sample for the system as a whole before valu- able wear data is removed by the filter. In addition, it is always best to take a sample where the fluid becomes turbulent. To identify a turbulent sampling location, deter- mine where the fluid is forced to turn and tumble, such as on a pipe elbow. This is important because without turbulence, heavier particles, such as wear debris, can be pushed past sample valve ports, especially with high fluid velocity. This particle fly-by phenomena can result in false low particle readings. If there is sufficient pressure, a sampling tube with an adapter affixed to a minimess valve can be used to draw the fluid into a certified clean bottle once the sampling lines have been flushed. If there is not sufficient pressure, a vacuum sampler pump will be required. When abnormal wear is evident in a primary sample taken after the lines converge, it will be necessary to obtain samples at secondary locations to determine where this wear is being produced. These sampling locations should be positioned immediately after the lubricant discharges from the component (e.g., bearing) before the line branches into the return header. Circulating Wet Sump Sampling Taking a representative oil sample from machine live zones can be challenging with a wet sump system, such as a diesel engine or circulating gearbox in which a return or drain line is not accessible or does not exist. In this type of system, there is a pressurized supply line or a kidney-loop filtration system. With a system containing a pressurized supply line, the most appropriate sampling location may be after the pump but before the filter. Because the sample is taken at a pressurized point, the best wet sump sampling after the pump but before the filter

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