You have vibration problems


YOU HAVE VIBRATION PROBLEMS ST018_5

There are several different types of vibration that include:

  • Mechanical causes of vibration
    • Unbalanced rotating components. Damaged impellers and non-concentric shaft sleeves are common.
    • A bent or warped shaft. This often happens during the removal of the shaft sleeve, the bearing, or the mechanical seal.
    • Pump and driver misalignment.
    • Pipe strain. Either by design or as a result of thermal growth.
    • Thermal growth of various components especially shafts.
    • Rubbing parts.
    • Worn or loose bearings.
    • Loose hold down bolts.
    • Loose parts.
    • The product is attaching to a rotating component, probably the impeller.
    • Damaged parts.
    • There is not enough mass or weight in the pedestal. If you weigh the pump and its driver there should be a least five times that mass in the pump pedestal.
    • The pedestal is not wide enough. If you drop a vertical line from the center of the motor, two lines radiating out thirty degrees from this centerline should pass through the base, not the sides of the pedestal.
  • Hydraulic causes of vibration
    • Operating off of the best efficiency point (BEP) of the pump.
    • Vaporization cavitation.
    • The impeller vanes are running too close to the pump cutwater.
    • Internal recirculation
    • Air is getting into the system through vortexing etc.
    • Turbulence in the system (non-laminar flow).
    • Water hammer.
  • Other causes of vibration.
    • Harmonic vibration from nearby equipment.
    • Operating the pump at a critical speed. Watch out for this problem in variable speed and pulley driven pumps.
    • Seal “slip stick” at the seal faces.
    • The product is vaporizing at the seal faces
    • A pump discharge recirculation line is aimed at the seal faces. Each pass of an impeller vane gives a pulse to the fluid going to the stuffing box.

Posted

  • On February 18, 2018