Centrifugal pump behavior when the outlet is closed

[Secan]

When the outlet is turned off there will be three things happen.

1. A small step increase in outlet pressure, as the flow stops.

2. A slight increase in RPM of the induction motor as pump load and slip is reduced.
The specified 3450 RPM will rise part way towards synchronous 3600 RPM.

3. The beginning of a gradual increase in temperature of water trapped in the pump.

Hi, I just read that cavitation can also occur when pump outlet is turned off. Wont this destroy the impeller too just like closed inlet? My plumber has not yet touched my systems because I am not sure he and his companion has Covid or not and awaiting vaccines. see:

https://www.google.com/amp/s/blog.craneengineering.net/what-is-pump-cavitation?hs_amp=true
"
When a pump's discharge pressure is extremely high or runs at less than 10% of its best efficiency point (BEP), discharge cavitation occurs. The high discharge pressure makes it difficult for the fluid to flow out of the pump, so it circulates inside the pump. Liquid flows between the impeller and the housing at very high velocity, causing a vacuum at the housing wall and the formation of bubbles.

As with suction cavitation, the implosion of those bubbles triggers intense shockwaves, causing premature wear of the impeller tips and pump housing. In extreme cases, discharge cavitation can cause the impeller shaft to break.

Possible causes of discharge cavitation:

• Blockage in the pipe on discharge side
• Clogged filters or strainers
• Running too far left on the pump curve
• Poor piping design"