×
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

How can I calculate the flow to depressurizing in a pipeline???

How can I calculate the flow to depressurizing in a pipeline???

How can I calculate the flow to depressurizing in a pipeline???

(OP)
How can I calculate the flow to depressurizing in a section of pipeline pressurized with air 60 psig?

RE: How can I calculate the flow to depressurizing in a pipeline???

Slide rule?  Calculator?  Excel?  MathCad?

I don't mean to be flippant, but your question is really wide open.  If you are depressurizing "a section of pipeline", the "flow" is whatever you can get through whatever size vent you have.  As long as the system pressure is above a critical value (call it 10 psig), the flow out the vent will be at sonic velocity.  For a given upstream pressure, you can calculate the mass flow rate of the air from the system at that velocity.  As the pressure comes down, the mass flow rate associated with the sonic velocity will decrease, so the "flow" from the system is a continuously varying parameter down to the critical pressure.

After the critical pressure, velocity rapidly drops away from sonic, and determining flow at any given second is really difficult.

If I may be allowed to read between the lines, people more often want to know the time required to depressurize the system.  That is pretty easy down to the critical pressure as long as you can determine the mass of air in the system.  I usually calculate the time to critical pressure carefully, then multiply it times 4 to get the total elapsed time.  My calculated time to critical is usually within a few seconds of actual.  My total time is never very close.  Sometimes I'm long, sometimes I'm short.  I've been doing this a long time and have never found an equation that even sort of works for the last 8-12 psig.  

David Simpson, PE
MuleShoe Engineering
www.muleshoe-eng.com
Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of Eng-Tips Fora.

"It is always a poor idea to ask your Bridge Club for medical advice or a collection of geek engineers for legal advice"

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