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Case Studies

What causes pump cavitation

April 10 2018

When a fluid has to be “moved” within a flow stream, pumps are used. In simple terms a pump is a machine which has the function of increasing the total energy of a liquid and is used to:

  • Move liquid from lower pressure area to a high-pressure area
  • To increase flow rate of the liquid within the stream
  • To move liquid from a lower elevation to a higher elevation

It can be tempting to speed up the process to move more liquid, or to slow down the process to save money on the pumping process, however over time that can cause significant problems, including cavitation and total pump failure.

To maximise efficiency and the life of a pump it needs to operate at its Best Efficiency Point. However, it is not a one size fits all solution – the size and type of pump required will depend on a range of factors including:

  • What you are trying to pump – clean vs dirty, oil vs water
  • Distance liquid is being moved
  • Elevation (see examples above); and
  • Allowable space to fit the pumping equipment.

For example, Allied Pumps was commissioned to supply the fire protection system to the Perth City Busport. There were a number of challenges to overcome with this project including – achieving sufficient fire water storage for fire protection in the underground terminal.

These factors in turn will determine the size of pump, pipes and fittings and the desired flow meter rates. In the case of the Perth Busport, our team were able to redesign the room layout, pump skid configuration and the tank dimensions to meet the restraints of the room size while still providing sufficient water to douse any potential fires within a short space of time.

PUMP PERFORMANCE CHART

WHAT CAUSES PUMP CAVITATION?

When the inlet pressure of a water pump falls below pump design specifications, tiny vapor bubbles can form in the water around the eye of the impeller. When the water containing these bubbles is forced into a high-pressure environment on the other side of the impeller, these bubbles collapse, thereby creating tiny shock waves and points of high temperature. These shock waves can actually corrode the surface of the impeller. To prevent cavitation, always be sure to operate your water pump within its pressure and flow specifications.

The second major problem that can cause pump cavitation is due to suction or discharge recirculation.

As we have discussed the pump is designed for a certain flow range, if there is not enough or too much flow going through the pump, the resulting turbulence and vortexes can reduce performance and damage the pump.

Get an honest recommendation from Allied Pumps

If you are unsure about what size pump you need please contact us. We’ll give you an honest, expert recommendation to get your pump operations running efficiently and effectively.

Contact the Allied Pumps Team

Contact us to learn about how we can help you with your pump needs.

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