Pumps vibration

[Dj364]

Hello Every one,
Does anyone could advise me where I can find materials for performing dynamic analysis?
we have received a vibration survey from the our client. vibration occured in existing suction and discharge centrifugal water pumps. I have never had a chance to perform such analysis, I would appreciate if someone could help , recommendation, tips on how to perform such analysis.
what data needed for the analysis?
in fact, we have received a vibration survey showing at certain points the velocities and displacement as well as frequncies...any advice on how to input these values into the system, and shall I consider all, or just input wherever is max? a brief explanation would be appreciable.
thanks in advance...

 

[nackra]

typically specs reference Hydraulic Institute stds

http://www.pumps.org/

 

[KernOily]

What are you trying to determine?

The source of the vibration?

Whether the vibration is too high?

 

[Dj364]

thanks for your reply,
we have received measured vibration and their frequencies ( displacement, velocities and frequencies at different point of the system...
Could you pls advise on how I will compute these parameters?
Thanks for your help.

 

[gerhardl]

For what purpose is the analysis?

Vibrations, as well as noise, in a waterpumping system, would be depending on sizable number of input parameters, including all pipe data with materials, masses, flow, bends, T-s, size, reductions and enlargement, all other components / valves, clamping details and distance, flexible pump/pipe connections or not,and details of supporting systems, influence from flows meeting or one or several pumps in series or parallell influencing on each other, soft or sudden starts and stops, waterhammer etc...

If vibrations are critical or outside acceptable parameters it would in my opinion be far simpler to check if one can diagnose to find the part of the construction / running mode contributing most to the vibration, and attack at this point....

Or am I far off ????

 

[Dj364]

Actually, a vibration survey had been conducted, at diffrent point they measured frequency, velocity and the displacment.
in some places the insulation got removed...
when run the modal analysis, and get the frequencies, shall I compare them with the frequencies they measured? or compare that to the RPM of the pump? to avoid the resonance problem??
Any thought regarding such analysis...
the content is water.
thanks,

 

[KernOily]

You still have not said what your problem is and what you want.

I assume you have taken vibration measurements of a pump and they are causing you concern because you think they are too high. Is that correst?

Is the pump experiencing failures?

Are your vibration measurements higher than an allowable limit?

For example, on some pumps, usually we use a velocity measurement of 0.3 in/sec as an alarm level. If the vibration is higher than that, we would see what is causing the problem. If the equipment is expensive, critical, or high horsepower, we would call in a specialist to perform a time and frequency domain analysis. That data will tell us whether the vibration is caused by such things as rotating element unbalance, soft foot, pipe strain, or issues with the fluid itself, such as cavitation, gas bubbles, or internal recirculation.

I suggest you take the data you have and retain an experienced vibration consutant/specialist for analysis and recommendations of your data. Do a web search for "machinery vibration consultants" and you will get many hits.

Heinz Bloch has written several books on machinery management and vibration analysis. Look on the Gulf Publishing website for his books.