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

Vertical can type centrifugal pump, Where?

Vertical can type centrifugal pump, Where?

Vertical can type centrifugal pump, Where?

Hi friends,
I know that for low NPSHa cases we have to consider to vertical can type centrifugal pumps.
But my question is what is the exact cut off NPSHa for going from conventional type cent. pump to mentioned pump?

Thanks for all replies.

RE: Vertical can type centrifugal pump, Where?

Hi Mohtogh
there is no magic NPSH value for going to a canned pump.
The canned pump is selected on economic grounds.
The comparison criteria is the NPV of a canned pump, its foundations spares, servicing arrangements and running cost versus the same for a conventional pump.
The canned pump comes into its own when the NPSH requires the pump to be sunk into foundations. The canned pump is more expensive, but the foundation costs are far lower.
For example, I have used then for extraction pumps from direct contact condensers on geothermal steam turbines.

There may be some other cases where the containment provided by the pump can favours the canned pump.



RE: Vertical can type centrifugal pump, Where?

Hello motogh,
There is a trade off if trying to find a pump with low NPSHr in order to work in a low NPSHa situation.  That trade off is that as you decrease NPSHr, the Suction Specific Speed rises, which at some point (perhaps around Nss > 9,000) then increases the need for greater margin of NPSHa over NPSHr, and rather dramatically too.  High Suction Energy pumps can require huge amounts of NPSHa over NPSHr, which you may never be able to satisfy.

It might be better to change the installation design, or live with a pump that will have very close NPSHa to NPSHr margin, than to go into a high energy suction pump and have it fail catastrophically and quickly.


RE: Vertical can type centrifugal pump, Where?

thank you.

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


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