×
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

Reducing pipe size at an inline air release valve in pressure sewer

Reducing pipe size at an inline air release valve in pressure sewer

Reducing pipe size at an inline air release valve in pressure sewer

(OP)
Our firm was called out to consult on a private sewer system malfunction.  Each house in this development is equipped with grinder pumps which pushes the waste water through HDPE lines ranging from 1.5" to 3".  In line flushing stations occur every 1000 feet typically.  At the high points in the lines, 2" combination air release valves are installed in manholes.  However, when an ARV is installed on a 3" line, it is reduced to 2", converted to brass within the manhole, and upon exiting the manhole re-sized back up to 3" HDPE.  The HOA has a drawing detailing this downsize, but I don't understand why the pipe diameter would have to be reduced.  Wouldn't a 3"x3"x2" brass tee allow for the 2" ARV to be installed without causing a "bottleneck" at these locations.

RE: Reducing pipe size at an inline air release valve in pressure sewer

The manufacturer is probably using a standard setup and has put little thought into the application.

There is no reason to decrease the pipeline to 2-Inch to install an air release valve. In fact, unless concentric reducers are used, the 2-Inch reducers could be trapping air as the force main narrows.

However, there is probably not a significant friction loss associated with the use of 2-Inch fittings unless your are dealing with multiple fittings on the same force main. There should not be much concerned with clogging either since everything has been through grinder pumps

In addition, there is no reason that brass fittings have to be used. A saddle fitting on the force main would be acceptable.

In general, automatic air release valves should not be used on force mains. Air release is necessary only on startup and can be done manually. Refer to the attached articles.

http://files.engineering.com/getfile.aspx?folder=f351191e-411c-4ba5-b72b-e62f13744789&file=0362_001.pdf

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