×
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

size of valve opening

size of valve opening

size of valve opening

(OP)
Hi everybody
I am working on a system that has a line cross sectional area of 0.0491 in^2, a velocity of 18.50 in/s and a pressure of ~11 psi.  I need to determine how large a valve opening should be made such that the pressure remains constant.  Is this possible without knowing the pressure downstream of the valve?  The cross sectional area remains the same before and after the valve.
Thanks for any help

RE: size of valve opening

I'm not sure of your question, but I think you would have to have flow data from a specific valve; it would depend on the valve configuration, not just the opening area.

What is the fluid in question?  And what pressure remains constant- upstream, downstream, or pressure drop across the valve?

RE: size of valve opening

hi f1

i think that you must choose the valve with higher Cv of the market, because the fluid always is going to have head loss in the valve.

RE: size of valve opening

f1-
Sounds like you're dealing with 2 unkowns, Cv and downstream pressure. You're going to need to pick one. If downstream pressure is not a factor, any valve will work. If you're concerned about agitation of the fluid you're valving, pressure drop may be a significant factor along with valve type selection.

Try picking a valve out of a catalog, use the given Cv and determine whether or not the pressure drop is acceptable.

Or, you could size you valve based upon the orifice size to maintain a minimum restriction of 1/8"

Hope this helps..

Schick

RE: size of valve opening

If the downstream pressure remains constant, any added valve will give a pressure drop.  Therefore the upstream pressure will change
If the flow is choked (independent of back pressure), then the flow with the added valve is basically proportional to the upstream stagnation pressure (and inversely proportional to the upstream stagnation temperature)
Valve area will then impact upsteam stagnation pressre.
I don't see how you can keep upstream pressure constant, unless something like a pump with a variable H-Q curve.

RE: size of valve opening

I need to determine how large a valve opening should be made such that the pressure remains constant.
which pressure u need it to be constant?
There should be a pressure drop while you have a valve or a fitting in the line.

What is the fluid and the its temperature?
By isentropic, there will be conditions change across the valve.

Regards

RE: size of valve opening

Would a pressure sustaining valve work in this application?

RE: size of valve opening

a sustaining valve only remains constant the pressure upstream but not equal the pressure upstream and downstream.

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