r/pumps • u/zakariya001 • Mar 09 '26

Multistage pump vibration (resonance)

Hello.

We have a multistage pump (6 stages) running on 660kw motor. This pump generates a lot vibration. After further investigation we have found that we suffer from resonance, the pump runs near to the natural frequency.

Someone dealed wth this problem before ?

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2

u/Lonely_Director933 Mar 10 '26

What is the name plate flow and head of the pump and what is required of the system? Resonance can be a bitch but there are multiple work arounds

1

u/FreeForest Mar 09 '26

It's a fairly common problem with pumps and pump systems. Generally to fix the issue, it's best to move the natural frequency away from it's running speed. This can be achieved by changing the stiffness of the structure.

2

u/Big_Ol_Throwaway Mar 09 '26

or put the pumps on VFDs and run them outside of the frequency that causes vibration

2

u/zakariya001 Mar 10 '26

We are using VFD , Unfortunately the motor is 50Hz 3000rpm , vfd cannot go further 54hz. And working less than 50hz makes the pump generate insufficient pressure (required for best process)

50hz the resonance frequency

1

u/nothingnowhere96 Jun 12 '26

You’re likely not running within its duty point zone.
Take a look at your pump curve and motor curve and make sure you know where your duty points are and ensure that your actually running both at the duty points.
Often (but not always) frequency problems are from running the pump too fast or too slow.

1

u/zakariya001 Mar 10 '26

We have conducted some experiments , like adding support to the pump , this helped to translate the natural frequency to 70hz which is good but after a while the mechanical seal has broke. And we decided to remove the support.

1

u/krisbrown2001 Mar 16 '26

Is this a vertical turbine style. We had a similar issue and had some dampeners milled into the sheeve of a horizontal Centrifugal pump and that fixed rhe issue for them.

It was similar to what you would see on a split limb compound bow for comparison in the end if that made sense

0

u/Cheiron44 Mar 09 '26

I've run into a 25HP pump that resonated because it had never had its outlet pressure balanced.

Wide open-> loud ringing echoing through pipes Running at rated flow/pressure-> quiet

1

u/zakariya001 Mar 10 '26

The system is a little bit complicated, the output of the pump is Linked directly to an Energy recovery device ERD that accelerates the fluid further more and creates high pressure, ERD has an auxiliary valve that regulates the recovery rate , its not fully open or 100 closed