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Recently I visited a customer’s facility to provide onsite training for the VibXpert vibration data analyzer they had recently purchased. Before we could get started collecting data,  we needed to build the equipment hierarchy and measurement templates required. Once the database was created, we loaded routes into the VibXpert and proceeded to collect vibration data.
The first room we entered had two large belt driven overhung fans. At first glance it was obvious that one of the fans was running extremely rough. We collected vibration data on both fans and paused to review the results. We noticed that the 1× amplitude on the rough fan was over 1.0 inches per second peek. The local CM technician immediately commented that the fan should be balanced and his observation was correct when simply looking at the vibration data.
The room was full of clues which explained the cause of the fan unbalance. This facility processed and manufactured wood products. Large amounts of wood dust are produced and these fans were designed to ventilate a high dust area. Everything in the room was covered with wood particles and dust. The only question was how much had accumulated on the inside of these fans.
I asked if the fan could be stopped for a short period and the inspection door opened. My request was honored and the fan was shut down and locked out. Our examination revealed the fan blades had amassed substantial amounts of wood particles. The fan blades were cleaned and resulting in a pile of wood chips weighing about 5 lbs. The fan was placed back into operation and allowed to run for several minutes. Vibration data was recollected on the fan and the 1× amplitude had reduced to 0.1 inches per second.
Fans require corrective action to eliminate unbalance conditions from time to time. However, the cause of unbalance may simply be buildup of foreign matter on the blades. This fan was being allowed to beat itself to death due to product buildup. This facility learned a few lessons from the experience. First, inspections utilizing the human senses (touch, hearing, etc) could have been used to determine that this fan was in need of attention. Second, periodic vibration monitoring would have identified a need for maintenance on this fan. Third, if a fan is properly balanced, simply cleaning foreign matter buildup may reduce the vibration, prevent equipment damage and maintain the reliability of the equipment. Make sure that you utilize these three steps during your daily maintenance efforts on equipment.

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, , by Dave Leach CRL CMRT CMRP