×
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

System Head vs Pump Head
2

System Head vs Pump Head

System Head vs Pump Head

(OP)
Hi,

May I know what are the other consequences if our Pump Head design larger than System Head? From my understanding, the pump will required excessive power.

For example, system head only required 30 m/98 ft but we use a pump that can delivered 50 m/164 ft at required flowrate.

#They design like this to give some margin for future expansion but after 10 years, no future expansion and no action to lower down the pump head

RE: System Head vs Pump Head

The system flow will usually increase. Flow will increase until system pressure drop equals pump total discharge head.

Your pump design head is significantly higher than what is needed. You can investigate if a control valve on the pump discharge will work. Control valves can be a good solution when you need 75 to 100% of pump rated head. That is still too high for your short term head prediction.
A possibly better option may be to install a VSD. VSD may work quite well, as you must lower the discharge head now by 40% or so. You could run the pump at about 75% of rated speed now and increase it using the VSD to higher speeds as more head is needed later on.

Einstein gave the same test to students every year. When asked why he would do something like that, "Because the answers had changed."

RE: System Head vs Pump Head

I don't understand your question.

So these look like theoretical numbers. What flowrate are you actually flowing at?

My guess is that if you have no pressure or flow control on the system then you're flowing at probably about 20-25% more than you think the basis of your 30m requirment, but every system is different dependoing on how much of that 30m is a static head and how much is friction losses.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: System Head vs Pump Head

You need to look at your pump curve to see how much more power you are using, but if its higher flow then it's less time so total energy might be less....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

RE: System Head vs Pump Head

Hi,
Probably good to review the basics. Consider the document attached to support your query.
Your Operating point is at the intersection between your pump curve and system curve.
You may want to share those curves with us.
Several options to consider:
a) Install a VFD
b) Trim the impeller.
note: Drop an email to the pump's vendor and request his/her support.
Good luck
Pierre




RE: System Head vs Pump Head

Great comments on the system. The system you have from your description sounds like it does not have and VFD (mentioned already) or any flow control devices like a triple-duty valve. If your system's primary loop is allowed to flow freely, do you have flow control on your terminal devices? Also, what is your pump speed (1800 rpm vs. 3600 rpm)? It might help if you have a high-speed pump with a low-speed TDH.

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