Machinery Lubrication magazine published by Noria Corporation
Issue link: https://www.e-digitaleditions.com/i/290460
www.machinerylubrication.com | March - April 2014 | 7 (infant mortality) and when it has exceeded its maximum useful life. Sampling frequencies must be modified according to the classic "bathtub" curve used to explain this probability of equipment failure. For this reason, sampling frequencies must be increased during these periods of higher failure probability, especially when analysis results indicate impending machine mortality. Oil Age The age rule applies to lubricants as well. Aside from the obvious new oil sample for baseline purposes, the lubricant needs a frequent recheck in the first 10 percent of its expected life. This is particularly true when a new oil type or manufacturer is used. Target Tightness The final consideration is the tightness of any goal-based limits. For example, if the ISO code 15/13/10 is set as the fluid cleanliness target and the average fluid cleanliness is normally around 14/12/9, then this would be considered tight. However, if it typically trends at 11/9/6, then this would be considered loose. Tight targets require more frequent sampling because the possi- bility of exceeding the target will occur more readily than with relatively loose targets. Sampling Locations A sample taken from an incorrect location can kill the accuracy of your oil analysis program. Understanding the differences between primary and secondary sampling ports can help you choose the proper sample location. Primary Sampling Ports The primary sampling port is where routine oil samples are taken. Oil from this sample location is generally used for moni- ROOT CAuSE DETECTION INCIPIENT FAuLT DETECTION PROBLEM DIAGNOSIS FAILuRE PROGNOSIS POST MORTEM What Oil Analysis is Telling You When something is occurring that can lead to failure – root cause conditions When an early stage fault exists that is otherwise unnoticed, e.g., abnormal wear What is the nature of observed problem? • Where is it coming from? • What is the failure mode? • Root cause? • How severe or threatening is the condition? • How much time is left? • Are corrective actions needed? What caused the machine to fail? Could it have been avoided? What You Monitor Particles, moisture, viscosity, tem- perature, additives, oxidation, AN/BN, soot, glycol, FTIR, RPVOT Wear debris, density, temperature, particle count, moisture, elemental analysis, viscosity, analytical ferrography Wear debris, elemental analysis, moisture, particle count, temperature, viscosity, analytical ferrography, vibra- tion analysis Elemental analysis, analyt- ical ferrography, vibration analysis, temperature Analytical ferrography, ferrous density, elemental analysis Maintenance Mode Proactive Predictive Predictive Run to failure Run to failure Relative Savings* 10 6 3 2 1 What Oil Analysis Can Tell You *10 = High, 1 = Low