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Guest post by Brad Loucks, Mechanical Engineer at Pioneer Engineering
In a condition monitoring vibration program, determining the appropriate intervals of data collection is just as important as the data that is being analyzed. Properly scheduled data collection intervals of equipment provides data analyst with a better picture of how equipment is performing over a period of time. Having a history of data is important for in an effective condition monitoring vibration program and this is done by establishing correct data collection intervals.
Data collection intervals should be established and executed with purpose, not done randomly. To establish intervals, it is important to know and understand how equipment works. Determining the appropriate time interval between collections is done by identifying how often the equipment runs, how fast it runs, and the application. The calculations are based on the estimated life cycle of the bearings but also the estimated amount of time it takes to go from a defect to complete failure.
Collection intervals should be a routine function. Many times data collection falls behind because the collection person is too busy to collect the data. One of the most common issues that I have come across is that plants will begin to collect data and then the person collecting the data gets pulled to do other work and the data collection gets missed and becomes more random. This is a slippery slope in that it almost always leads to the data no longer being collected. Then when an emergency comes up such as a bad sounding machine, the analysis has not been collecting a history on the equipment but they have also been out of the analysis for so long that they have a difficult time remembering how to analyze. The history and interval is just as important for a proper analysis as it helps to give the analyst a more accurate analysis by allowing them to see the progression timeline.
Bearings often do not fail in a predictable time span. If this were the case, vibration analysis could be overlooked and time-based maintenance could be used. A bearing can go from a known defect to catastrophic failure over the course of a few years or it can happen within minutes. The collection intervals are calculated so that not only can data be collected and the severe defects be identified, but also to identify when a defect has formed and allow for a history to be built in order to watch the progression of the defect. This can aid in determining whether immediate action should be taken or if the defect is at an early enough stage where proper planning and measures can be taken to avoid an immediate shut down and loss of production.
If the equipment is deemed valuable enough or if unplanned downtime is just out of the question, then calculated collection intervals are a necessity of a proper condition monitoring vibration program. Through proper maintenance, a condition monitoring vibration program can save a plant both time and money in reducing or eliminating unplanned downtime, as well as significantly reduce the possibility of injury or death of plant staff due to catastrophic equipment failure.
Download our Calculations of Bearing Defect Frequencies

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, by Ana Maria Delgado, CRL