Machinery Lubrication

Machinery Lubrication May June 2014

Machinery Lubrication magazine published by Noria Corporation

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44 | May - June 2014 | BeNNett FItCh | NorIA CorPorAtIoN Oil analysis plays a critical role in a lubrication program, allowing you to have confidence in the quality of the lubri- cant in a machine and to analyze the health of the machine in its current state. The problem is that several facets of oil analysis must be performed correctly or the integrity and validity of the entire program will be at risk. The first requirement for effective oil analysis is to obtain a representative sample. This involves using proper sampling bottles (discussed in Part 1 of this series), employing appropriate extraction tools and procedures (detailed in Part 2), and determining the optimum sampling location and frequency, which is the focus of the third and final part of this series of articles. Where to Sample In all the time I've spent walking around heavy machinery at plants, the one thing I seem to always find lacking is the proper location to sample oil. If a sample is not taken at the right location and in the correct manner, it becomes increasingly difficult to ensure the representative nature of the oil analysis results. Success- fully trending data becomes even less of a possibility. Choosing the sample location should be based on obtaining fluid in a machine's most important lubrication zone — the live zone. For a rolling-element bearing, this would be the lubricant between the rollers and the race. For a gearbox, it would be the lubricant between meshing gear teeth. While it may not always be possible to take a fluid sample adjacent to the gear teeth, attempting to sample in close proximity or where the fluid returns back to the reservoir can be just as effective for maximizing data density and minimizing data disturbance. Following are sample locations for three types of machines: a dry sump circulating system such as a turbine lube oil system, a wet sump circulating system like a diesel engine, and a non-circu- lating system such as a bath/ splash-lubricated gearbox. Circulating System Sampling A dry sump circulating system contains a central reservoir, a pump, various components to be lubricated, a filter and piping to connect them all together. A sample for this type of system should always be taken just down- stream of components that may produce wear, since any wear l u b r i c a n t s a m p l i n g lessoNs IN lUBrICAtIoN Anatomy of a representative oIl sAmPle: Part 3 ─ sampling Frequency and location 64% of lubrication professionals rate machine criticality as the most important factor to consider when adjusting oil sampling frequency, according to a recent survey at Sampling Frequency variables

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