×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Are you an
Engineering professional?
Join Eng-Tips Forums!
• Talk With Other Members
• Be Notified Of Responses
• Keyword Search
Favorite Forums
• Automated Signatures
• Best Of All, It's Free!

*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.

# Open Vent Sizing Using API 520

 Forum Search FAQs Links MVPs

## Open Vent Sizing Using API 520

(OP)
Hi,

Previously I posted about the same topics regarding sizing of open vent (i.e. gooseneck vent) so this time after I did my own research and this is what I wanted to find out from other experts here.

In API 2000 there is not mention about sizing for open vent, only basis of sizing for venting (something like that, i didn't remember). However after reading briefly on API 520 Part-1, I stumbled across this equation for sizing for critical and subcritical flow, and also for steam conditions and liquid phase.

Okay, now my question is that for API 650 which is low pressure atmospheric storage tanks, the design internal pressure is 0.75 kPa(g) and vacuum of 0.25 kPa(g), based on my earlier sizing calculations I checked that for a vent sizing (for critical flow) the downstream pressure shall be less than the upstream pressure in this case, the internal pressure shall be bigger than the outside pressure.

So here, shall I take directly the downstream pressure as -0.25 kPa(g) or should I just consider it as 1 ATM (101.325 kPa(a))? If say I take it as 1 ATM, my pre-requisite checking would end up to be SUB-CRITICAL flow which will be my upstream pressure to be lower than my downstream pressure.

I would really like to know if my assumption here is correct or otherwise. Appreciate the useful answer thanks.

### RE: Open Vent Sizing Using API 520

Its 1 atm (corrected for altitude) outside and either 1 atm + 0.75 kPa or 1 atm -0.25kPs inside.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

#### 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.

#### Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!

Close Box

# Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

• Talk To Other Members
• Notification Of Responses To Questions
• Favorite Forums One Click Access
• Keyword Search Of All Posts, And More...

Register now while it's still free!