KCF Technologies Blog

There's a Major Difference Between Vibration Monitoring and Vibration Analysis

A SmartDiagnostics® wireless vibration sensor on a pump at a wastewater
treatment facility.
Dating back to 1905, Gardner Denver Nash --"your source for industrial vacuum and compressed gas solutions" -- has its offices in Pennsylvania, Brazil, Germany, and China.  The firm provides improved global service and technical support for Nash liquid ring vacuum pumps, compressors, and engineering systems serving the chemical, petroleum, power, paper, mining, environmental, food, and wastewater treatment industries.  It also produces a thought-provoking quarterly newsletter.

One of its newsletters last year featured a brief, unsourced piece on "Vibration Analysis vs. Vibration Monitoring."  It's conclusion was unexceptional: "Implementing the proper maintenance plan will have a positive impact on the longevity of you equipment."  But, it found that the difference between monitoring and analysis can be the difference between merely piling up a lot of numbers and insightful comprehension of actual machine performance.

"Companies heavily depend on maintenance to keep equipment running, but simply monitoring bearing vibrations at set intervals may not be the best way to evaluate equipment.  When monitoring and analyzing bearings the trend data, the equipment may seem to be operating correctly when in fact it is not.  An example of this comes from a 2007[-09] case study at a wastewater facility in Washington, D.C."

"Briefly, the wastewater treatment facility began tracking the reliability of it's pumps in 2007 using vibration analysis.  Working with a simple analyzer, a rotating machinery technician examined any pump with high vibrations.  Due to the quantity of pumps and the multiple plant locations, it was difficult to service the pumps before they had issues.  By the time attention was given to problematic pumps, extensive repair was needed--which increased the cost as well as the downtime."

In 2009, the company shifted...to a monthly monitoring schedule.  This new approach helped to reduce the cost associated with catastrophic failures.  The problem with monthly trending is that you can occasionally have higher than normal vibration peaks and they could go unseen in the overall trend data.  Even though they were having fewer failures, they were still not able to determine the problem pumps before there was an issue.  After discussion with an outside consultant, it was determined that a continuous monitoring system would solve their problem."

Triaxial vibration/temperature sensors on the pumps were connected to data modules that sent measurements by radio to a communications module, which relayed the signals to a tower, which transmitted them to a company network.  The result?  "Plant technicians, maintenance personnel, and other operators could view the data directly on their computers, via the internet, from any location.  The results showed that vibrations spiked from a low level of approximately 0.05 inches per second...to a high level that was close to the 0.5 inches per second alarm level.'

Predictive, preventive, and proactive maintenance all have their places in any water and wastewater treatment system.  But, vibration monitoring--just observing that pumps vibrate from time to time--is by no means the same as vibration analysis--recording patterns of vibration when and as they happen, tracking non-standard patterns and peaks, and intervening in time to schedule needed maintenance and avoid downtime.

Photo by Christopher Shannon/KCF Technologies.  All rights reserved.

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