×
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

Reservoir drainage wet well vacuum relief

Reservoir drainage wet well vacuum relief

Reservoir drainage wet well vacuum relief

(OP)
I am designing for a vacuum relief pipe for a drainage inlet wet well. A couple of 48" dia pipes from a reservoir drain into the wet well, which in turn is piped via a 72" dia pipe to a pump station. The design flow of the pump station is 160 MGD. The vacuum relief design is in anticipation of the either the reservoir inlet valves or pumps misfuctioning so that the pumps are pulling vacuum, requiring inlet air from the top of the wet well to prevent pump or wet well damage. The wet well is 90 ft tall and 14 ft dia. What factors would be used to calculate the size of the vacuum relief pipe?

RE: Reservoir drainage wet well vacuum relief

I would call it a vent, but that's just semantics.  For steel tanks, a good rule of thumb is to provide the outlet pipe diameter for the vent.  This makes the air pressure at 40 fps about 1/2 inches and doesn't exceed the roof live load.  The 40 fps would be caused by some kind of pipe break.
Make sure the vent can work if frosted over and that it is screened to keep critters out. The open area of the screens should exceed the pipe area.
Take a look at AWWA D100 for some suggestions and details.

RE: Reservoir drainage wet well vacuum relief

You have to determine the worst case scenario for opeations. If the liquid will overflow through the vacuum valve, the valve would have to be sized for the maximum liquid rate. If the valve will only have to relieve air, then the valve is typically sized for a higher air flow velocity.

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