siphon collapse

[1PE]

I'm designing a large diameter siphon to dewater a deep mine pool. I am currently considering 12" diameter DR 11 HDPE Pipe with fused connections.

My first question is this "If I break or lose siphon will the pipe have a good potential to collapse?"

Secondly, the siphon will be operating at a minimum pressure of about negative 11 psi. Are there adjustable vacuum release valves available which can be set to operate at a negative pressure of 11 psi and release the vacuum at a setting of say negative 15 psi?

Thanks in advance for any responses.

 

[smckennz]

If DR is the diameter divided by the wall thickness, the 50 year critical buckling pressure for unsupported PE80B is 476kPa. This gives a reasonable safety factor over the full vacuum differential of 100kPa. A safety factor of 2 to 2.5 is often recommended, and in this case it is 4.76 So it wont suck flat.

Bleeding air in to control vacuum is dodgy at best; unless velocities are high enough to sweep away the air, you run the risk of losing prime.

Cheers

Steve

 

[Ag93]

1PE,

Check out our website,

http://www.performancepipe.com.

Request an engineering CD. There are some calculations for unconstrained buckling on the CD plus many more design calcs. If you have questions call me.

Kevin Deal
Performance Pipe
936-321-8940