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Reducing cavitation risks with variable speed drives

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Many fluid handling applications can be affected by cavitation, but it is a particular challenge for the water and wastewater industry where a high number of pumps are deployed.
The result of cavitation is an increased risk of downtime and higher maintenance costs. The issue goes beyond the need to replace a damaged pump. In remote areas, in particular, the cost of sending a maintenance team with heavy lifting equipment to the site might be many times the cost of the pump itself.
Cavitation can happen when the pumping process subjects a liquid to rapid local changes in pressure, creating vapour-filled bubbles. The exact point at which this liquid-to-vapour transition occurs depends on the pressure. At normal atmospheric pressure, water transitions into steam at 100°C. When the system pressure is reduced, this occurs at lower temperatures. Eventually, when the pressure is reduced to a vacuum, the transition happens at room temperature.

Low pressure

When the impeller is spinning in an industrial centrifugal pump, high pressure is created on the front side of the blades. Simultaneously, there is low pressure on the back of...

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