×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

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!
  • Students Click Here

*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

Jobs

CHW Pump Pressure
3

CHW Pump Pressure

CHW Pump Pressure

(OP)
Had a heated argument so just want to have clear understanding on this thing. When we are calculating pressure head for chilled water pump, we include all fittings and losses occur through the farthest route of CHW piping with corresponding flow including the return lines. My understanding is, this pressure is nothing but the differential pressure we have maintain across pump (Discharge - Suction Pump)to get the desired supply flow (as per pump selection or curve)

RE: CHW Pump Pressure

For a closed loop system where the pressure is maintained such that the highest point of the piping is kept at positive pressure - correct. You don't mention it specifically but also include losses through the AHU or whatever you plan to use the CHW for.

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

RE: CHW Pump Pressure

Pump discharge pressure - Pump suction pressure= Differential head developed by the pump= System pressure drop

RE: CHW Pump Pressure

(OP)
Thanks Folks...!!!

RE: CHW Pump Pressure

Just pointing out a nuance - your index run may not be the furthermost point in the system. sometimes a closer item may have a higher pressure drop through it's coil and therefore become the system index. 99% of the time your statement is correct though.

RE: CHW Pump Pressure

(OP)
Correct. Thanks.

RE: CHW Pump Pressure

(OP)
What are the possible reasons if i received correct flow but not correct differential pressure (as per the pump performance curve)?

RE: CHW Pump Pressure

poor readings?

Different voltage

Variance in pump performance

Give us a bit of a clue here - how much different?

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

RE: CHW Pump Pressure

Are you sure you are looking at the correct impeller size? Are you running at full rpm?

RE: CHW Pump Pressure

(OP)
There are 3 pumps running. I could expect any one might have problem, but its unlikely that all three might have or may not have same issue. @pump 1: suction pressure is 2 bar and discharge is 5.3 bar. dP 3.3 bar. At 3.3 bar my flow to be 50 l/s as per performance curve, but in fact i am getting 75 l/s (which is req. as per design).

RE: CHW Pump Pressure

I'm still confused by your reply. With three pumps (I assume in parallel) you will have a different flow characteristic than you would with only one pump running. Are you looking at the combined pump curves of all three in parallel?

RE: CHW Pump Pressure

Can you post pump curve.

Also check the electric current if you can and check all three pumps at the same time.

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

RE: CHW Pump Pressure

(OP)
@BronYrAur
Yes these are in parallel. As per design Total flow required @ common Chiller supply header is 223 l/s. So three pumps in parallel (@ 75 l/s each , all are of same model/capacity)

RE: CHW Pump Pressure

You may well find that one pump is doing 50 and the other two 85... There are many many threads on this forum about parallel pumping issues and mismatch between supposedly "identical" units.

Lik eI said - post the pump curve if you have it and also try and see how many amps each pump is taking when operating in parallel. It's sometimes easier to measure Amps than fluid flow.

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

RE: CHW Pump Pressure

Have you checked the pump impellers for wear or other variances?

RE: CHW Pump Pressure

(OP)
You are correct Williard.

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

White Paper – Data Security and Know-How Protection
Our data is constantly exposed to the danger of being intercepted or stolen as it wends its way over global data networks. Data security measures and measures for protecting intellectual property should not, however, first be implemented when data is exchanged – companies must lay the foundation for these measures within their own organization. Download Now
White Paper – Collaboration in the PLM Context
The influence exerted by the Internet of Things (IoT) means that there is a steadily growing need for collaboration in industry. Partners from new industries and areas of application need to be integrated in cross-company business processes to ensure that the lifecycle of smart, connected products can be managed from end to end. 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