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marksl

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Posts: 150
Reply with quote  #1 
Hi,

I have a client who has several centrifugal pumps used to load tankers in a fuel terminal. One of the pumps shows intermittent indications of cavitation which we attribute to the short time we have to collect the data before the electric valve begins to close as the tanker gets close to full. The last data collection shows a large increase in VP frequency with harmonics into the HF range. There is also a marked increase in random impacting in the time waveform. The client wants more proof that cavitation is the cause of the changes.
Has anyone had any success with using clamp on ultrasonic flow meters and comparing the results to the pump curve which I've obtained from the O.E.M

Thanks in Advance
Shurafa

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Posts: 310
Reply with quote  #2 
Do you notice the presumed cavitation (vibration increase) as the flow decreases (tanker approaches full)?

Where is this contol valve (upstream or downstream the pump)?

Regards- Ali M. Al-Shurafa
RustyCas

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Reply with quote  #3 
Keep in mind that any kind of "flow noise" in a pump is presumed to be "cavitation". Cavitation is actually a very particular set of conditions, usually associated with inadequate suction head (pressure).
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John from PA

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Reply with quote  #4 
Have you listened to this pump?  A pump that is undergoing cavitation will typically have increased vibration, decreased output and will often make a noise described like that of marbles going through the pump.
RGf

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Reply with quote  #5 
In an earlier life I did perhaps 500 ultrasonic flow measurements on various piping ranging from 1" diameter up to 48" with varying degrees of confidence in the measured flow. Configuration is the key in getting repeatable measurements you can rely on. If you just want to get an idea on where your running on the curve you could look at the driver load if you don't have sufficient instrumentation on the pump. Determine BHP and compare that to the OEM specs as most curves will have that plotted also.  
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