Up Time Magazine- August/September 2008

Table 1: Effect of Moisture Content on Machine Life Life Extension Factor (LEF)* Moisture 50,000 ppm 25,000 ppm 10,000 ppm 5,000 ppm 2,500 ppm 1,000 ppm 500 ppm* 250 ppm 100 ppm 2x 12,500 6,250 2,500 1,250 625 250 125 63 25 3x 6,500 3,250 1,300 650 325 130 65 33 13 4x 4,500 2,250 900 450 225 90 45 23 9 5x 3,125 1,563 625 313 156 63 31 16 6 6x 2,500 1,250 500 250 125 50 25 13 5 7x 2,000 1,000 400 200 100 40 20 10 4 8x 1,500 750 300 150 75 30 15 8 3 9x 1,000 500 200 100 50 20 10 5 2 10x 782 391 156 78 39 16 8 4 2 Figure 4 - Dual-face magnetic bearing housing seal (MagTecta®, www.AESSEAL.com) * Example: Reducing the water content of an oil from previously 500 ppm to now 45 ppm would increase bearing life by 4 (300 percent). cost-justifying modern bearing housing seals is greatly facilitated. Table 1 represents data published by Noria Corporation. It allows us to enter a current, known moisture ppm (parts per million), and to move across to an achievable reduced moisture ppm. The resulting Life Extension Factor (LEF) can be obtained from the top line. Likewise, the LEF for reduced amounts of contaminants can be obtained from Table 2 (www.royalpurple.com). product by 2, will yield a combined bearing life multiplier. The writer proposes to use this realistic factor in cost justifications. Say, for example, the contamination levels are known and improved cleanliness would yield LEF’s of 3 and 4, respectively. The product of the two numbers is 12 and dividing by 2 yields 6. It can be anticipated that oil with contaminant levels thus reduced will allow bearings to live 6 times longer. Table 3 - ISO 4406:99 Cleanliness Standards* Range Number 24 23 22 21 20 Number of Particles per ml More Than 80,000 40,000 20,000 10,000 5,000 2,500 1,300 640 320 160 80 40 20 10 5 2.5 1.3 .64 .32 Up To & Including 160,000 80,000 40,000 20,000 10,000 5,000 2,500 1,300 640 320 160 80 40 20 10 5 2.5 1.3 .64 Table 2 - Effect of Solid Particle Contamination on Oil-Lubricated Rolling Contact Bearing Life* Life Extension Factor (LEF)* 19 18 17 A/B 26/23 25/22 24/21 23/20 22/19 21/18 20/17 19/16 18/15 17/14 16/13 15/12 14/11 13/10 12/9 2x 22/19 21/18 20.17 19/16 18/15 17/14 16/13 15/12 14/11 13/10 12/9 11/8 11/81 11/81 11/82 3x 20/17 19/16 18/15 17/14 16/13 15/12 14/11 13/10 12/9 11/8 4x 18/15 17/14 17/14 15/12 14/11 13/10 13/10 11/8 5x 17/14 16/13 16/13 14/11 13/10 12/9 11/8 6x 16/13 15/12 15/12 13/10 12/9 11/8 7x 15/12 14/11 14/11 13/10 11/8 11/8 8x 15/12 14/11 13/10 12/9 11/8 9x 14/11 13/10 13/10 11/8 10x 14/11 13/10 16 15 14 13 12 11 10 9 8 7 6 1 - Life Extension Factor 1.5 2 - Life Extension Factor 1.3 * Example: Improving the ISO 4406 cleanliness level of an oil from previously 20/17 to now 13/10 would increase bearing life by 4 (300 percent). * Note: The classification rating follows a geometric progression where each level decreases in cleanliness and is twice as dirty as the previous level. Oil cleanliness levels may be reported using either a two or three digit rating. Based on Table 2, the cleanliness level of an oil with a particle count of 2000 > 4 microns, 500 > 6 microns and 60 > 14 microns would be reported as 18/16/13. LEF’s make it easy to calculate with reasonable accuracy and conservatism the intrinsic value of modern bearing housing protector seals. Simply multiplying the Life Extension Factor for moisture reduction obtained from Table 1 by the LEF for reduced particle contamination shown in Table 2 and then dividing the www.uptimemagazine.com Or assume, in another example, that actual plant failure statistics indicate one’s present, “contaminated” bearings to last 1.9 years, and that data given by the bearing manufacturer showed a load and speed dependent L-10 life of 84,000 hours (or 9.6 years) with very clean oil. We could now reasonably expect that with well-sealed bearing housings, i.e. bearing housings with plugged vents and oil cleanliness assured by retrofitting either modern rotating labyrinth or dual-face magnetic seals, bearing lives of 9.6 years would be reached. Bearing life will thus be extended five-fold and several repairs will be avoided. With suitable advanced bearing protector seals and even magnetic seals typically costing considerably less than one 27 http://www.AESSEAL.com http://www.royalpurple.com http://www.uptimemagazine.com

Table of Contents Feed for the Digital Edition of Up Time Magazine- August/September 2008

Up Time Magazine- August/September 2008 Contents Upfront Upclose Information Technology Lubrication Infrared Maintenance Management Motor Testing Precision Maintenance Reliability Ultrasound Vibration Upgrade

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