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Vibe-Rater

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Reply with quote  #1 
Hi All,

Has anyone ever installed a dynamic pressure sensor on the pressure side of a hydraulic pump / ahead of a hydraulic cylinder?

If so what suitable brand and sensor is available?  Just doing some prep work for a possible job that could be requested.  Max pressures and other detail will become available early next week.

Normal vibration data show usual rotational vibration and 9x which is vanepass. No change for years but will take more data next week.

Any suggestions welcome, especially the brand and type of sensor suitable for connection to a spectrum analyser. rgds
Walt Strong

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Reply with quote  #2 
I have used a dynamic pressure sensor on centrifugal fan, centrifugal pumps, and Hydro turbine. I use the PCB Piezotronics brand that are ICP -type. Some key considerations for choosing a pressure sensor are:
1) Expected maximum dynamic pressure
2) Frequency range
3) Maximum temperature
4) Mounting method/restrictions

The best frequency response is obtained when the microphone diaphragm is flush with the inside wall of the pipe. Pipe acoustics such as standing waves and cross modes may affect assessment of true pressure. Note that the ICP piezoelectric sensors do not measure static pressure. The alternative would be to use strain gauge type pressure sensor capable of measuring both static and dynamic pressures. I've used this type as well.

What is "unusual rotational vibration"? What is the type of pump: gear, vane, or piston? What kind of information are you looking for from the dynamic pressure sensor?

Walt
Vibe-Rater

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Reply with quote  #3 
Thanks Walt,

There's a surface barring issue on a large steel roll (confirmed synch averaging) and we are trying to figure out how that happened.  Client thinks it is coming from the hydraulic pump loading another roll (much different diameter) which presses against the large roll. My gut tells me not related but client has been running around with hi phone and an app doing FFT's and found a frequency close to the barring. On top of this the rolls are variable speedd depending on grade run. Hyd pp is fixed speed 4 pole (25Hz) with 9 vanes.  I have routine data on the pumps going back years.  Will get more info next week re confirming a vane pump and max pressure etc.

I guess we are not discounting that the barring set in at a particular speed then locked in after that although I think it is over thinking but you can't be so blunt to client. rgds
John from PA

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Reply with quote  #4 
If this is a one-time deal I'd consider renting. See http://www.modalshop.com/rental/ICP-pressure?ID=942.
Vibe-Rater

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Reply with quote  #5 
Thanks John, I'll see if they rent from local distributor here in Australia.  By the time we rent from US it is bound to be close to purchase price once you take into account freight time and witing time to shut, then install, test and wait for following shut to remove etc.  May prove better to buy one then we can keep for future. Thanks for the link.

I did have one when I was with my previous employer who chuck it in the garbage when doing a clean out. Oh I hate them for that.  It was a PCB unit as well.
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