Siphon - Requirement for Submerged Discharge?
Siphon - Requirement for Submerged Discharge?
(OP)
Colleagues,
I am designing a pipe siphon to effect the drawdown of a reservoir under emergency conditions. To give a sense of scale I've done a preliminary sizing at 0.5m dia.
I've struggled to find any good guidance on the design of this type of installation (there seems to be plently out there on self priming and air regulated siphons, but less on the basic 'pipe over an embankment' type).
Much of the guidance I have managed to find suggests that the downstream end needs to be submerged. This is going to be difficult in the situation I am designing for (discharge half way down the existing spillway) so my question is - why? If this is for priming, can I get away from needing it by having a valve at the downstream end which is closed during priming?
I'd also be grateful for any suggestions on a source of good design guidence on this type of siphon.
Thanks,
Graham
I am designing a pipe siphon to effect the drawdown of a reservoir under emergency conditions. To give a sense of scale I've done a preliminary sizing at 0.5m dia.
I've struggled to find any good guidance on the design of this type of installation (there seems to be plently out there on self priming and air regulated siphons, but less on the basic 'pipe over an embankment' type).
Much of the guidance I have managed to find suggests that the downstream end needs to be submerged. This is going to be difficult in the situation I am designing for (discharge half way down the existing spillway) so my question is - why? If this is for priming, can I get away from needing it by having a valve at the downstream end which is closed during priming?
I'd also be grateful for any suggestions on a source of good design guidence on this type of siphon.
Thanks,
Graham





RE: Siphon - Requirement for Submerged Discharge?
When we were kids - we used to scavenge every hose we could find in the neighborhood in order to siphon our neighbors pool - so we could clean it, paint it and THEN SWIM!! We would fill the hose with one kid on each end holding it closed. Then we would yell to each other and get the siphon going. It would run for days - worked great.
RE: Siphon - Requirement for Submerged Discharge?
See page 11.3.7 Siphons:
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A stilling basin is probably necessary on the discharge side to ameliorate other problems such as turbulence and erosion.
The valve that you selected may be used instead of a submerged discharge. Note that the vale may collect debris and plug with debris. The valve may be a freezing issue as well.
h
RE: Siphon - Requirement for Submerged Discharge?
Hydrology, Drainage Analysis, Flood Studies, and Complex Stormwater Litigation for Atlanta and the South East - http://www.campbellcivil.com
RE: Siphon - Requirement for Submerged Discharge?
http://en.wikipedia.org/wiki/Siphon
RE: Siphon - Requirement for Submerged Discharge?
The only time I have found where air will travel up the hose and break the siphon action is when the flow is reduced due to a lowering of the available head, or when the flow is restricted due to an obstruction in the line. Otherwise, it's just fine.
Mike McCann
MMC Engineering
Motto: KISS
Motivation: Don't ask