Machinery Lubrication


Machinery Lubrication magazine published by Noria Corporation

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6 | September - October 2017 | This article will describe industry- accepted tests for predicting lubricant life, including results from real commercial lubricants. Many of these tests are used by formulators when designing and evaluating new lubricants. Comparing and analyzing these actual test results will reveal how to examine informa- tion from various resources and help you make better decisions about your lubricants. The Lubricants The lubricants in this study were turbine oils, which fall in the category of rust and oxidation (R&O) fluids. The samples tested included one polyalkylene glycol (PAG) oil and three different mineral oil formulations. The mineral oil formulations were chosen from a list of commercial products based on the American Petroleum Institute's Group II and II-Plus base stocks. They consisted of an older formulation, a new formulation and a new premium formulation. The PAG formula - tion was based on a Group V (synthetic) base stock. There are three types of synthetic PAG oils: water soluble, water insoluble and oil soluble. This study focused on water-insol- uble PAG turbine oil. To complete the study, in-service lubricants were also obtained for these formulations if available. The Tests Since newer lubricant formulations may not have been in operation long enough for a comparable long-life measurement, bench aging tests are of ten used. The industr y's accepted aging tests include ASTM D2272, D2619 and D665(A). The lubricants in this study were aged by these standard test methods to assess their suitability for operation first as new lubricants. After the aging tests were performed, the lubricants were measured to determine their condition. The second group of analytical tests included ASTM D5185, D6304(C), D665(A), D974, D2272, D1401, D6971, D7414, D7843 and D892. Compatibility The first consideration when changing lubricants is whether the new lubricant and the in-service lubricant are compat- ible. This issue can impact flushing and change-out decisions as well as result in significant costs. Group V synthetics are of ten thought to be incompatible with Group I-IV hydrocarbon fluids. This should be the first issue addressed, but it is also one of the easiest to answer. ASTM D7155 explains how to test fluids for compatibility. In this study, lubricant ratios of 90-to-10 and 95-to-5 were tested using two different Group II lubricants with

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