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enter image description hereim monitoring an overhung pump 19kw . and it shows a high peak at 7x rpm . on Thrust Vertical DE of pump.

what does it mean ?

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  • $\begingroup$ Is there resonance with what it is connected to? A diagram would help... It could mean anything or nothing - so broad at the moment. $\endgroup$ – Solar Mike Mar 27 '19 at 16:25
  • $\begingroup$ sorry . here is the spectrum of the mentioned point. Thanks for your help . $\endgroup$ – Houssame Paco Mar 27 '19 at 16:34
  • $\begingroup$ Does the pump have 7-bladed impeller? Or 7 outlet guide vanes? $\endgroup$ – alephzero Mar 27 '19 at 19:00
  • $\begingroup$ yes its a 7 bladed impeller $\endgroup$ – Houssame Paco Mar 28 '19 at 7:14
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According to the OP's comment, the pump has a 7 bladed impeller. Each blade will cause some disturbance to the pressure and/or velocity in the flow. Those disturbances will cause a force on the mounting of the pump.

The text on the OP's picture says the pump RPM was 2940, or approximately 50 revolutions per second. The frequency of the disturbances in the flow is therefore about 350 Hz. Maybe the pump and the structure it is mounted on has a natural vibration frequency close to 350 Hz moving in the vertical direction, and that is why you are getting a large amplitude on your plot.

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  • $\begingroup$ ok I see. we are going to check the gap between the casing and the impeller .. $\endgroup$ – Houssame Paco Mar 29 '19 at 9:19

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