Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/359954
56 | July - August 2014 | www.machinerylubrication.com Right Sampling Location It is critical that samples are taken from the proper location, i.e., from a "live zone." If a sample is drawn just below the surface of the oil in a gearbox, the particle counts will not be very accurate. The same holds true when sampling from a drain plug on the gearbox. Most of the particles will settle to the bottom of the reservoir. If you have a high particle count when sampling from the top of the reservoir, there is a serious contamination issue. Likewise, if you are sampling from the bottom of the reservoir, you should expect elevated particle counts. Of course, neither of these locations will give you an accurate count of the particles at the gear mesh, which is where the damage is actually occurring. In a circulating system, samples should be taken at an elbow on the return line prior to the filter. In the gearbox example, I recom- mend that a minimess sample connection be used in conjunction with a pitot tube to allow samples to be drawn consistently from a location near the gear mesh. Right Frequency If you are only sampling your equipment on an annual basis, I would surmise that in most cases this is not enough. Several factors should be considered when determining the sampling frequency such as the age of the equipment, the age of the lubricant, the machine's criticality, etc. Right Procedure You also must ensure that each sample is representative of the fluid in the reservoir and not affected by outside contaminants. A minimess allows a sample to be drawn without opening the reser- voir. In addition, by keeping the sample bottle in a plastic bag, you can prevent airborne contaminants from entering the bottle. Drawing a sample from a drain valve with the cap off the bottle enables airborne contaminants to enter the sample. Depending on the environment, this can lead to severely elevated particle counts, essentially rendering the sample useless. Right Equipment Sampling equipment should be kept in a clean environment and cleaned after each use and prior to storage. Use minimess sample connections and select sample bottles based on the cleanliness targets. Sample bottles come in three categories: clean, super- clean and ultraclean. In every manufacturing process, a certain amount of particles is generated. A bottle's cleanliness relates to its signal-to-noise ratio. Ultraclean bottles generally are made of glass and are shipped in hermetically sealed vacuum packaging. Right Alarms and Limits Many of the plants I visit have robust oil analysis programs. Sadly, several of these programs have improperly set alarms and limits. In the July-August 2011 issue of Machinery Lubrication, Jim Fitch explained how world-class organizations are taking charge of their own alarm settings to ensure that specific objectives are met. He also detailed how the advent of sophisticated oil analysis software has put this objective within reach of most anyone who desires it. To learn more about how to set both proactive and predictive limits for oil analysis, see http://www.machinerylubrica- tion.com/Read/28520/setting-oil-analysis-limits. Right Data interpretation Strategy Even if the right lab has been selected, the right test slate is chosen, the right sampling equipment is used, the right proce- dures are followed and samples are taken from the right location, if you don't employ the right data interpretation strategy, it is the same as having an all-encompassing encyclopedia and never opening the book. To make the best use of your oil analysis data, you may need to do a bit of homework. Elemental analysis of the lubricant can give you an idea of the composition of the wear metals in a given sample, but if you aren't familiar with the metal- lurgy and internal machine configuration, you are likely to suffer some confusion and have to guess as to where the wear material is being generated. Keep in mind that the rights of oil analysis are all equally important. No one specific right takes precedence over another. Each of these rights must be addressed and applied correctly. Otherwise, your time, effort and money will be wasted. When used properly and combined with other condition monitoring technologies, oil analysis can enable your maintenance program to reach its full potential. About the Author Loren Green is a technical consultant with Noria Corporation, focusing on machinery lubrication and maintenance in support of Noria's Lubrication Program Development (LPD). He is a mechanical engineer who holds a Machine Lubrication Technician (MLT) Level I certification and a Machine Lubricant Analyst (ML A) Level III certification through the International Council for Machinery Lubrication (ICML). Contact Loren at lgreen@noria.com. BACk PAge BAsICs Each of these rights must be addressed and applied correctly. Otherwise, your time, effort and money will be wasted. 54% of lubrication professionals utilize offsite oil analysis testing, according to a recent survey at machinerylubrication.com