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  1. wht66

    Cavitation damage to casing on suction side - Why?

    It's been two months, I know, but I'm back with more details and questions! Some additional particulars: 1/ The cavitation damage is all on the suction side and predominantly on the inside and outside of the wear ring support spigot, although there is also significant damage to the flow...
  2. wht66

    Cavitation damage to casing on suction side - Why?

    This is an issue I have not been able to explain. The noise from the pump continues during discharge valve closure, and if anything seems to become worse. This does not make any sense to me at all, especially given that the pumps are starting at 25% right of BEP. From leaning on the...
  3. wht66

    Cavitation damage to casing on suction side - Why?

    Thanks for your comments, BobPE and Scipio. I am sorry if I seem to be drip-feeding information - that's not my intention. BobPE, there is a short length (about 500mm) of DN400 leading to the suction flange of the pump after the contraction. The contractor tried to reduce the contraction...
  4. wht66

    Cavitation damage to casing on suction side - Why?

    Thanks BobPE. The 8m head (NPSHA-NPSHR) is just before the pumps, ie after the bends, so I'm still a bit puzzled. I was interested to see your comments on why there would be cavitation on the casing and not the impeller. I haven't actually measured the head, but at a tapping point about 1m...
  5. wht66

    Cavitation damage to casing on suction side - Why?

    The pump is operating at 1450rpm. 8m difference between manufacturer's NPSHR and NPSHA, ie should be plenty of head available. The pump is operating significantly to the right of BEP, apparently due to differences between the "design" condition and the actual operating condition (ie...
  6. wht66

    Cavitation damage to casing on suction side - Why?

    I am investigating three treated water pumps (in the same installation) that have experienced significant cavitation damage to the pump casing on the suction side. The pumps typically operate with about 8m NPSH, have a cast iron casing and bronze impeller. There is no noticable cavitation...

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