×
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

NPSH-pump suction with compensation loop

NPSH-pump suction with compensation loop

NPSH-pump suction with compensation loop

(OP)
Hi All,

I was asked to review if existing centrifugal pump handle a new suction line arrangement. Pump used to "suck" water 0.7 meters below pump CL and now a compensation loop going 2.5 meters above pump CL was added. My concern is if i should consider 0.7 or (0.7+2,5) meters in static head in calculations. At the begining of suction line foot valve is installed so pipe will be kept flodded. I need it to be sure that in the system is enough NPSHA.

In my opinion during the start up a system will have to overcome 3,2 meters of static head at suction side so I considered this in calculations.

thanks
Rob

RE: NPSH-pump suction with compensation loop

I can't visualize this without a big chance for making a stupid guess.  Can you save me the potential embarassment and attach a diagram?

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

RE: NPSH-pump suction with compensation loop

At least 3.2  There's more, so plus flow resistance of foot valve, the 4 ells around the goosneck plus all the pipe from the bottom of the riser to the pump suction flange.  Once the gooseneck fills, then the -3.2 will cancel with the +3.2, but you still have the rest of those NPSH parasites still eating it up.

**********************
"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/

RE: NPSH-pump suction with compensation loop

(OP)
Thanks BigInch. Yes I added friction losses of piping and fittings.

cheers

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