Tech Tip: Pump Cavitation

Centrifugal pump cavitation can be described as the formation and eventual collapse or implosion of vapor bubbles inside a pump.

A primary cause for cavitation is inadequate net positive suction head available (NPSHa). Poor NPSH leads to lower liquid pressure in the pump and if pressure in the eye of the impeller falls below the vapor pressure of the fluid, then cavitation can begin. When this takes place, the following can occur:

  • Pitting on impeller blades
  • Bearing failure
  • Mechanical seal failure
  • Shaft breakage
  • Poor efficiency

Preventing this type of pump cavitation may require several changes in system design or operations. Increasing pressure at the suction of the pump, decreasing the temperature of the liquid being pumped, and reducing head losses in the pump suction piping can increase the NPSH.

Implosion of vapor bubbles that form within the liquid inside a pump is what causes cavitation. Determining if this abnormal condition is taking place and how to correct will be vital to the longevity of your pump.

Sources: Engineers Edge, Enggcyclopedia

About J.R. Banks

Process Systems Assistant Product Manager, Nelson-Jameson, Inc.
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