×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

NonSynchronous Vibration at Vertical Cantilever Pump

NonSynchronous Vibration at Vertical Cantilever Pump

NonSynchronous Vibration at Vertical Cantilever Pump

(OP)
Hi all,

We got high vibration on 1.66X shaft speed of a vertical cantilever pump (at 2250 cpm). The RMS of Motor NDE bearing is 13 mm/s (being the highest). The motor is variable speed with rated of 1475 rpm. During the measurement the speed was 1349 rpm. Any thoughts on why this is happening? This has been a steady problem since a long time. But it is not detected with online vibration of DCS because they only measure the RMS on pump DE bearing horizontal. For more detail, I attach below the spectra.


The time waveform:





The picture of the pump itself:


Looking forward for any thoughts and advices.
Best regards,

Yosep

RE: NonSynchronous Vibration at Vertical Cantilever Pump

Does the vibration remain high if the speed is increased 9% or decreased 10-15% ?

The position labels on the spectra are too small to read.
I //think// the vibration is not just a simple reed motion of the pump system above the floor

Regardless, I believe it is self excited ( by flow ) vibration at one of the natural frequencies of the LONG thin poorly supported pump assembly.
Are there other identical pumps on site that do not have that vibration?

I'd investigate several aspects of the installation.
1 - The design of the sump vs ANSI / Hydraulic Institute Standards, and observe the sump while the pump is online looking for vortices etc.
2 - There are several mechanical interfaces that can seriously muck with the system natural frequencies. Mostly lower them numerically compared to any of the manufacturer's simplified modeling and calculations.
Motor to pump, pump to motor support, motor support to pump head, pump head to sole plate, sole plate (grouted and bolted) to floor.
2A - I'd make a vibration map of the sole plate and floor and add liquid to sole plate to floor joints to test for motion/pumping there. Using nuts on anchor bolts on the underside of the sole plate to level the pump before grouting is pretty much guaranteed to end up with a weak, flexible joint no matter how hard the anchor bolt nuts are tightened.

hhttps://www.gouldspumps.com/getattachment/Products...

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members! Already a Member? Login


Resources

Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close