The Peaks Provide the Early Warning in Machinery Protection

by | Dec 8, 2011 | Asset Management | 0 comments

I was in Knoxville this week visiting our Machinery Health Management team. They are the team behind the Emerson CSI Technologies machinery monitoring and analysis products. I had the chance to sit down and connect with Emerson’s Robert Skeirik, who leads the wireless program. We discussed a wide range of issues with the health of plant assets. Critical assets such as generators, compressors, turbines, and boilers typically have continuous monitoring and predictive systems applied, such as the CSI 6500 system.

Robert discussed a whole class of essential plant assets that fall just below the critical assets in importance to the process. Depending on the process equipment where they are located, they typically include pumps, fans, motors, and gears. In some cases, equipping them with vibration monitoring has been physically or economically out of reach. The CSI 9420 wireless vibration transmitter was developed to address these difficult installation areas.

Through the wireless gateway, vibration and PeakVue diagnostic information is available to the operators through their control system operator workstations.

Robert spent time explaining the PeakVue diagnostic with me as it relates to ball bearing monitoring. Imagine a very small pit in the road. It is a pit on its way to becoming a pothole. You likely wouldn’t feel anything driving over it while it was still a pit but would feel as it grew into a pothole. And, the bump impact would feel greater the faster you drove over it. It’s much the same way as ball bearings roll over a slight defect in the bearing inner or outer race. As the defect gets deeper or the RPMs increase, the size of the impact peak increases. The PeakVue diagnostic is designed to detect the impact while the defect is still small.

This PeakVue digital signal samples over 50,000 times per second. It needs to sample this fast to pick up any ball bearing impacts, which may last only microseconds. Traditional vibration measurements incorporate signal-processing techniques that diminish or even completely remove the amplitude of these impacts. They wouldn’t show up as anything more than “road noise”. In contrast, the PeakVue technology not only captures the event but also detects the peak value of the impact. Since the amplitude of the impact correlates to the severity of the fault, this gives operators an intuitive way to track the development of a mechanical defect.

Robert shared an illustration of what the relative vibration and PeakVue readings might look like on a typical process pump as it moved through the 5 stages of bearing failure:

  1. Less than 20% bearing life
  2. Less than 10%
  3. Less than 5%
  4. Less than 1%
  5. Imminent failure

It is important to note that the traditional vibration signal (left) is close to the first alert level during normal operation. This is the “road noise” involved with normal operation. In comparison, the PeakVue reading on a good machine should be at or close to zero.

Robert stressed to me that the key is to provide a simple diagnostic to the operators that can serve as early warning to get a maintenance action initiated in time to maintain the health of the equipment and keep the process operating smoothly. This provides the ability to plan when and how best to maintain the equipment, helps to shorten the downtime involved, allows planned personnel and parts scheduling, and helps avoid any secondary damage to other machines.

We covered numerous topics during our conversation, which I’ll share in future posts.


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The opinions expressed here are the personal opinions of the authors. Content published here is not read or approved by Emerson before it is posted and does not necessarily represent the views and opinions of Emerson.

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