×
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

Pressure Drop Across An ESDV

Pressure Drop Across An ESDV

Pressure Drop Across An ESDV

(OP)
Hi all,

I am back with one more question (a simple one for those with experience) and will appreciate any help.

I am doing a sizing exercise for a gas plant and need to size some shutdown valves for a client. What pressure drop will be used in the CV calculations? Is it the operating pressure upstream of the valve? Since the plant/process is shut down when the valve is activated, logic tells me that the pressure on the downstream side should be zero. So, if our pipeline operating pressure is 800 psig, the pressure drop across the valve should be 800 - 0 = 800. Am I right?

If I am wrong, what is the rule of thumb? How do I calculate the pressure drop across the valve since only the pipeline pressure is know?

What about for liquid lines? Does the same logic hold?

RE: Pressure Drop Across An ESDV

One does not normally size an SDV. These valves are normally in line ball, plug, or gate valves. Their size is the pipeline size. The pressure drop is based on the flow and valve Cv. However, since these valves are shut down valves, when specifying the shut off differential pressure, use the maximum upstream and minimum downstream pressures.

--Mike--

RE: Pressure Drop Across An ESDV

I'm sorry but I don't really understand your issue. CV is only really needed for control valves, not ESD valves. ESD valve issues are normally about actuator sizing as they need to seal against flow and full pressure (design pressure one side - not max operating, zero the other) in a short period of time and with some form of stored energy, usually a spring (a big one). This has very little to do with valve CV.

Same thing for liquid lines.

Valve CV is only of use if you have flow. If you have flow past your ESD valves then you're in big trouble, but please let me know if I'v emisunderstood your question / issue.

My motto: Learn something new every day

Also: There's usually a good reason why everyone does it that way

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