Machinery Lubrication

Machinery Lubrication May June 2014

Machinery Lubrication magazine published by Noria Corporation

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54 | May - June 2014 | Before joining Noria as a technical consultant, I served in the U.S. Navy where I was stationed aboard the USS Sara- toga and assigned to the oil lab. Prior to placing equipment into operation onboard the ship, we would draw an oil sample and conduct a visual analysis. If the sample was "clear and bright," it was considered acceptable, and the equipment was placed into service. I now know that using the "clear and bright" standard is not nearly good enough. Particles that cause the majority of damage in equipment are smaller than can be seen with the naked eye, and lube oils can contain up to 0.1 percent water and still be "bright." Keep in mind that at 0.1 percent water, 75 percent of the bearing's life may have been lost. Oil Analysis in the Navy The following excerpt is from the Navy's Machinist Mate 3 & 2, which is the advancement training guide for steam plant operators, heating and air conditioning technicians, and ship oil kings: "Lubricants must be maintained at specified standards of purity and at designed pressures and temperatures. Without proper lubrication, many units of shipboard machinery would grind to a screeching halt." Note the phrase "specified standards of purity." Prior to starting a piece of equipment, one of the requirements is to draw an oil sample. This sample is sent to the shipboard oil lab for analysis. According to the Machinist Mate 1 & C, the procedure is as follows: "The visual test must meet the clear and bright criteria. Clear refers to the lack of particulate matter in the sample. Particulate matter cannot cover more than one-quarter of the bottom of the sample bottle. The bright criteria refer to the lack of free water in the sample. Entrained water can dull the lube oil sample. If the sample is dull, try to read a PMS card through the sample. If you can read the PMS card, it passes this test. If it does not pass the visual test, you need to run a BS&W test. Be careful of entrained air that may dull the sample. If you are unsure whether air or water is the cause of the dullness, let the sample settle a few minutes. Air will clear to the top of the sample; water will settle to the bottom." If the oil sample contains particles longer than 1/8 inch along any axis or if visible sediment is noted, the procedure is to let the sample bottle sit for 10 minutes and then lay it on its side for 10 minutes or until all visible sediment has settled to the bottom. If this results in a solid line, a bottom sediment and water (BS&W) test is required. The BS&W test involves spinning 100 milliliters of the oil sample at 1,500 revolutions per minute for 30 minutes and then recording the results. Generally, results of less than 0.1 percent by volume are acceptable. Samples are sent periodically to a Navy oil analysis program laboratory for testing. The test slate will be dependent on the type of oil and the associated equipment class. The table below shows the test slate based on fluid and application types. For oils designated for equipment lubrication, a spectrometric o i l A n a l y s i s loreN greeN | NorIA CorPorAtIoN why CleAr and Bright oIl sAmPles are Not good enough BACk PAge BAsICs OIL TyPE/APPLICATION TEST PERFORMED LIMITS ALLOWED MIL-L-9000/Lube Oil (MS 9250) Diesel Engine Oil • Viscosity at 100ºF • Water Content • Acidity Test • Fuel Dilution • *Spectrometric Analysis Performed 100-225 Centistokes Pass/Fail 0-2% Satisfactory 2-5% Notify Customer 5% Abnormal: Secure Machinery MIL-L-17331/Lube Oil (MS 2190TEP) Marine Turbine Oil • Acid Number • Water Content • *Spectrometric Analysis Performed 0.5 Mg KOH/g max. 0.1% max. MIL-L-23699/Lube Oil Aircraft Engine Oil • Viscosity at 100ºF • Acid Number • *Spectrometric Analysis Performed 25-37 Centistokes 1.0 Mg KOH/g max. VV-L-825/Lube Oil Refrigerant Oil • Water Content • Acid Number • *Spectrometric Analysis Performed 0.01% Max. 0.1 Mg KOH/g Max. MIL-L-17331/Hydraulic MIL-H-17672/Hydraulic MIL-H-5605/Hydraulic MIL-F17111/Hydraulic • Water Content • Particle Count 0.05% Max. NAS Class 9 Max. MIL-H-83282/ Hydraulic • Water Content • Particle Count 0.05% Max. NAS Class 7 Max. MIL-H-19457/Hydraulic • Water Content • Acid Number • Flash Point • Particle Count 0.3% Max. 0.3 Mg KOH/g Max. 475ºF Min. NAS Class 12 Max. MIL-H-22072/Hydraulic • Viscosity at 100ºF • pH • Particle Count 41-51 Centistokes 8.2-10.0 NAS Class 9 Max.

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