Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/1032074
48 | September - October 2018 | www . machinerylubrication.com BACK PAGE BASICS or ultrasound technology for grease applications. Using a synthetic lubricant is another option. Synthetics commonly offer higher viscosity indexes for dealing with a wider temperature range. Also, be sure the correct type of bearing is utilized for the particular application. While there is some overlap between oil-filled vs. grease-filled bearings, it is important the correct decision has been made. When evaluating between the two, consider speed, location, environment, contamination level and local temperature. Moisture Most sampled lubricants have some amount of moisture. If moisture is allowed to increase, it can lead to failure. Moisture accumulates in a lubricant through several mechanisms, such as handling, storage and general use in the system. It is worth noting that moisture appears in three distinct forms: free, dissolved and emulsified. e most common problems related to moisture are additive depletion, hydrolysis, cavitation wear and water- washing. Additive depletion occurs due to excess water contamination soaking up polar additives. e process of hydrolysis arises through the breakdown of base oils and some associated additives, thus accelerating the oxidation process. Cavitation wear is activated through pressure increases in the lubricant when moisture is present. As cavitation takes place, it can cause damage to exposed surfaces. Water-washing presents failure concerns in both grease and oil. Grease water-washing tends to happen through direct contact of water spray with a bearing. In oils, moisture ingression through water-washing typically occurs through the seals. Moisture Elimination Strategies Hardware modifications, lubricant changeouts and component alterations can all be employed to eliminate moisture. Just like with particle contamination, the installation of suitable breathers and filters can also help to address moisture contamination. Again, it is important to understand the parameters of your equipment when selecting filters and breathers. Bottom sediment and water (BS&W) bowls are another good option for identifying and removing moisture. One thing to consider with BS&W bowls is that you are not preventing moisture from entering the system but simply addressing it once it is already present. Vacuum dehydrators and dialysis equipment are other alternatives that can aid in the elimination of moisture currently in the system. A lubricant-related strategy would include using a lubricant with high demulsibility properties. is exploits the oil's ability to separate from water, thus making it easier to remove moisture from the system. Reservoir containment, headspace f low, sealed bearings and enclosed motor applications are among the various component strategies. Creating headspace flow will minimize humidity, draw moisture from the lubricant and aid in the prevention of condensation in the reservoir. The Road Ahead As you begin to understand the different lubrication failure modes, including why they occur, how they affect lubricants and how you can mitigate or eliminate them, a culture change should begin to take place with new instal- lations and equipment overhauls. Although this is not a quick process, like most successful initiatives, it should pay off over time. Eventually, maintenance personnel should see their repetitive task load begin to shrink, and those lingering PM backlogs will be reduced. ML References Neale, M.J. (1973). "e Tribology Handbook." Woburn, MA: Butterworth Heinemann. Scott R., Fitch, J.C., & Leugner, L. (2012). "e Practical Handbook of Machinery Lubrication." Tulsa, OK: Noria Corporation. About the Author Matthew Adams is a technical consultant for Noria Corporation, concentrating in the field of predictive main- tenance. He has experience in multiple condition-based maintenance technologies and focuses the majority of his attention on lubrication program development, training and general consulting. Matthew holds a Machine Lubricant Analyst (MLA) Level II certification and a Machine Lubri- cation Technician (MLT) Level I certification through the International Council for Machinery Lubrication (ICML). Contact Matthew at madams@noria.com to find out how Noria can help control contamination and reduce machine failures at your plant.