Water Purification Plant Pre-Construction Specialized Vibration Testing for Future Improvements

By January 4, 2017
vertical turbine pump operating deflection shape ODS

A construction firm needed help identifying potential issues with future pump motor replacements at a water purification plant.  MSI was called to conduct specialized vibration testing on the current units and to predict how a motor change and future variable frequency drive operation (VFD) would impact the system.

water purificaton plant vertical turbine pumps

  • Problem Statement (Challenge)
    • What (type of machine):Water Purification Vertical Turbine Pump
    • Where (State/ Country): Massachusetts
    • Why (problem/reason): A construction firm needed help identifying potential issues with future pump motor replacements at a water purification plant. MSI was called to conduct specialized vibration testing on the current units and to predict how a motor change and future variable frequency drive operation (VFD) would impact the system.
  • Work Performed
  • Results/ Solution
    • Findings: The testing predicted that future operation would not be trouble-free due to possibilities of structural natural frequencies being present in the future VFD operating range. Although the vibration levels measured on the current pump system met the HI/ANSI specification for this style pump, a motor modification would change that.  ODS testing indicated that the discharge head, soleplate, and foundation were properly connected.
    • Impact: The findings led MSI to recommend a finite element analysis (FEA) of the system (calibrated to the data collected in the field) including the new motor to make modifications, preventing future issues.  This pre-construction analysis saved headaches down the road that would have come up due to structural natural frequency resonance.  This allowed the construction firm to be proactive in the new motor implementation and avoid having to deal with a project delay penalty clause.
vertical turbine pump operating modal analysis FRF

Experimental modal analysis results.

vertical turbine pump torque strain gauge FFT plot

FFT plot from strain gauge on pump shaft

vertical turbine pump operating deflection shape ODS

Click image to animate

vertical turbine pump table of predicted new natural frequencies

Predicted natural frequencies from manual calculation