×
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

CLOSE CIRCUIT PRESSURE

CLOSE CIRCUIT PRESSURE

CLOSE CIRCUIT PRESSURE

(OP)
Hello.

we have a close circuit chilled water system suppling the water to a heat exchanger located at 30 meters height, the pump is located at ground, the suction pressure is 4 barg and the dischrge is 8 barg.
when the pump is stopped what will be the pressure in the return line at 30 m height and at ground? will it be the same pressure?
what are the rules to calculate the pressures in close pumping circuits/

regards,
         roker

RE: CLOSE CIRCUIT PRESSURE

Think about it & do the Bernoulli thing. If the pump is stopped, the dynamic pressure drop goes away. You have to determine the fixed pressure point (usually an expansion drum of some sort) and calculate static pressure differentials from there.
If you have high flowrates and suddenly stop a pump you can run into water hammer problems. Then a dynamic analysis is required to give you the transient pressure profile.

Cheers,
Joerd

Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.

RE: CLOSE CIRCUIT PRESSURE

4 barg at suction is a concern to me, could it be 3barg? Also, the 4 barg differential seems to be too high (just a gut feeling). Check with the designed pressure drops and it may be right time for cleaning.

RE: CLOSE CIRCUIT PRESSURE

Roker,
Do you have a chilled water surge and expansion drum near the suction of the pump? This would be my experience and joerd's as well I note.

The pressure at which this drum is operated at shutdown will be needed to determine the pressures at points of the system based on the elevation relative to that drum. From the info you have given, the pressure at the top of the loop (30m) could be 1 bar (i.e. holding 4bar on drum minus 30m of elevation) or vacuum (if water is allowed to slump into the drum at shutdown).
best wishes,
sshep  

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!


Resources