×
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

Check Valve Proximity to a Centrif Pump Discharge

Check Valve Proximity to a Centrif Pump Discharge

Check Valve Proximity to a Centrif Pump Discharge

(OP)
Can the check valve sit right on the end-suction centrifugal pump discharge flange, or there must be a certain straight pipe run in between? How many Ds? Before or after encreaser? Any specific reference guidelines document? Thank you.

RE: Check Valve Proximity to a Centrif Pump Discharge

It is possible to mount a check valve directly to a centrifugal pump discharge flange and some skid mounted pump packages do come through that way.  Typically, however, there is an increaser mounted on the pump discharge ahead or the check valve.  This is usually done to avoid the velocity head losses associated with the "same size" check valve.  Swing check, ball check, butterfly and spring disc type check valves all have reduced port sizes and tend to restrict flow considerably.

Be aware also that if you are pumping anything with solids entrained, sewage for example, the bigger the port size, the better.

RE: Check Valve Proximity to a Centrif Pump Discharge

I agree with GrampaRoy.  None of my references address this, so two more suggestions.  1) ask the manufacturer after you have selected the pump 2) try posting on the pump engineering forum, those mechanical guys love questions like this.  

Good luck.

RE: Check Valve Proximity to a Centrif Pump Discharge

SOme check valve manufacturers specify 6D straight lengths upstream of a check valve.

Geoffrey D Stone FIMechE C.Eng;FIEust CP Eng
www.waterhammer.bigblog.com.au

RE: Check Valve Proximity to a Centrif Pump Discharge

Piping Handbook published by McGraw Hill calls out a minimum requirement of 5 diameters of straight pipe (upstream). The straight pipe is necessary to avoid potential chattering of check valve caused by upstream turbulence. The reference also says that some check valve manufacturers may require up to 10 diameters.

RE: Check Valve Proximity to a Centrif Pump Discharge

Check valves are like control valves - they're typically one size smaller than the correctly sized line. This means that the flow will drive them wide open, and hold them in that position. Otherwise, the disc will flap up down like a flag in the wind, and this is what causes a huge number of checks to wear out far before their time. Crane's Technical Paper No. 410 covers this. I've got the Crane ABZ software that actually has a window pop-up on the screen alerting you to the fact that the size of check valve selected for a given set of flow conditions will not open fully, possibly resulting in a greater pressure drop than the correctly sized (smaller) valve.

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