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#99221 - 10/10/07 02:34 PM How Does the Pond Dam Piping SyponSystem Start?
rock creek Offline
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Registered: 06/27/05
Posts: 14
Loc: Kansas
I am installing the pond dam piping syphon system. Is it necessary for the level in the pond to rise above the level of the pipe through the top of the pond dam? Also, does the level of the pond have to rise over the small vent pipe in order to start the syphon? Any advice will be appreciated.

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#99226 - 10/10/07 03:41 PM Re: How Does the Pond Dam Piping SyponSystem Start? [Re: rock creek]
Ryan Freeze Offline
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Registered: 10/31/05
Posts: 1284
Loc: Southwest Ohio
The way I understand it, Not really and yes. In a basic setup water will flow out through the pipe as long as the water level is higher than the bottom of the highest point of the pipe. This can be just a trickle without actually creating a siphon. A true siphon action will not start until the pipe is filled enough that the weight of the water on the downhill side is enough to pull water up the intake. If there was enough water flowing to actually start a true siphon then the water would continue to be drawn through the system until until either the water drops below the intake pipe or siphon break vent pipe. Whichever is the highest will break the siphon. It is possible that your siphon system would never truly siphon but you'd still get the benefit of pulling "dead" water off the bottom of the pond if your intake pipe went deep enough.



Edited by Ryan Freeze (10/10/07 03:44 PM)
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#99228 - 10/10/07 04:12 PM Re: How Does the Pond Dam Piping SyponSystem Start? [Re: Ryan Freeze]
rock creek Offline
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Registered: 06/27/05
Posts: 14
Loc: Kansas
Ryan: Thanks for the info. My syphon pipe intake on the pond side (water side of the dam) is about ten feet below the normal surface level of the pond. The bottom of the syphon pipe running thru the top of the dam is about 3 inches above normal pond level. The bottom of the vent pipe is about 2 inches above normal pond level

If I understand your post correctly, the syphon pipe will begin to run (but not syphon) if the pond level rises above the bottom of the syphon pipe running thru the top of the dam. The syphon action will probably not start unless the water level rises pretty much over the top of the syphon pipe going thru the top of the dam. If the syphon action starts, it will stop when the vent pipe is above the level of the pond.

I am probably going to raise the elevation of my emergency spillway to ensure the level of the pond will engage the syphon action before running off thru the emergency spillway.

If I have understood your advice please confirm that I have.

Thanks very much for your input.

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#99229 - 10/10/07 04:54 PM Re: How Does the Pond Dam Piping SyponSystem Start? [Re: rock creek]
Greg Grimes Offline
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You can always call the folks at PDPiping as well. The pipe going through the dam sets you lake level. I think this is the same but stated differently. It is gravity feed system everyday. When the lake is full and water running it simply goes through the pipe and out the back. Siphon stats when pipe level is full and vent tube under water, once the vent tube catches air it will shutoff. The emergency spillway should be halfway between lake level and top of dam height ( quite a bit above the air vent if you have enough freeboard. good luck!
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#99255 - 10/10/07 10:17 PM Re: How Does the Pond Dam Piping SyponSystem Star [Re: Greg Grimes]
zhkent Offline
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Registered: 03/18/04
Posts: 229
Loc: Burlington, Kansas
Your vent line needs to be high enough to let all the air out of the pipe system in the dam. Otherwise the trapped air stays in there. The pipe will still let water overflow through it, but will not run a full pipe or really move water during a high water event as long as there is air in the system.



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#99276 - 10/11/07 11:26 AM Re: How Does the Pond Dam Piping SyponSystem Star [Re: zhkent]
rock creek Offline
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Registered: 06/27/05
Posts: 14
Loc: Kansas
Kent: Thanks for your input. There seems to be several views on the elevation to use for when the vent pipe is under water for the syphon action to start. The Pondampiping diagram shows the elevation of the vent pipe to be at the elevation of bottom of the pipe running thru the top of the dam. I admit that your explanation makes sense -ie. the air must be out of the pipe for the syphon action to start; but, if I could get the syphon action to start at a lower level, say at the elevation of the bottom of the pipe running thru the top of the dam, it would allow the syphon action to run longer and obtain a lower water level.

Does anyone else have a comment on the elevation of the vent pipe with respect to how it allows the syphon action to commence?

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#99277 - 10/11/07 11:53 AM Re: How Does the Pond Dam Piping SyponSystem Star [Re: rock creek]
Ryan Freeze Offline
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Registered: 10/31/05
Posts: 1284
Loc: Southwest Ohio
It sounds like you've got the idea. You could experiment with a large paper cup and one of those straws that bend at the top or a piece of clear hose. The red dot in my illustration shows where you could locate a vent hole for further experimentation. Once the vent hole is added the water should only siphon down to the height of the vent hole. Keep in mind that once siphoning has begun, should the vent hole become plugged the water will drop until air enters the system at the intake. Basically emptying your pond if the intake goes all the way to the bottom.

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#99284 - 10/11/07 01:29 PM Re: How Does the Pond Dam Piping SyponSystem Star [Re: Ryan Freeze]
Greg Grimes Offline
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Registered: 05/03/02
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Loc: Ball Ground, GA
ryan nice diagram. I have alwyas been told the siphon will not "kick in" until there is a full pipe of water. Vent tubes on clietns lakes vary from below the top of pipe to 4 inches above the pipe.
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#99285 - 10/11/07 01:45 PM Re: How Does the Pond Dam Piping SyponSystem Star [Re: Ryan Freeze]
Chris Steelman Online   content
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Registered: 02/26/06
Posts: 1356
Loc: Red River County,Tx
 Originally Posted By: Ryan Freeze
Keep in mind that once siphoning has begun, should the vent hole become plugged the water will drop until air enters the system at the intake. Basically emptying your pond if the intake goes all the way to the bottom.


I think that is the best advice. Make sure you have a trash rack around the vent. One of the ponds at my deer lease had the vent hole get plugged up and it almost drained the entire pond.
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#99336 - 10/11/07 10:38 PM Re: How Does the Pond Dam Piping SyponSystem Star [Re: Chris Steelman]
zhkent Offline
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Registered: 03/18/04
Posts: 229
Loc: Burlington, Kansas
Ryan,
In your second pic how did the air get out the top?
The air won't go out the ends because they are lower.
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#99406 - 10/12/07 03:55 PM Re: How Does the Pond Dam Piping SyponSystem Star [Re: zhkent]
Ryan Freeze Offline
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Registered: 10/31/05
Posts: 1284
Loc: Southwest Ohio
The air that is trapped will be pushed out of the outflow end once the weight of the water has overcome it either due to the pressure from the weight of the water above or the suction developed from the weight of the water below once the lower part of the pipe is filled. It will work as long as there isn't significantly more air trapped in the high section of the pipe than there is water filling the lower section of the pipe. Try the experiment.
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#99408 - 10/12/07 04:07 PM Re: How Does the Pond Dam Piping SyponSystem Star [Re: Ryan Freeze]
Ryan Freeze Offline
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Registered: 10/31/05
Posts: 1284
Loc: Southwest Ohio
To further demonstrate that water can be sucked/pushed down try this. Take a clear piece of aquarium air tubing or any clear tubing a few feet long and completely submerse it in a bucket of water. While under water let all the air escape from the tubing and cap off one end with your thumb. Pull out the capped end and lower it below water level while leaving the other end in the water. Remove your thumb and allow the siphoning action to start. While the water is flowing, very quickly pull the end in the bucket out of the water and put it back in. You should see a pocket of air travel through the tubing and out the lower end.
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#99440 - 10/12/07 10:21 PM Re: How Does the Pond Dam Piping SyponSystem Star [Re: Ryan Freeze]
zhkent Offline
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Registered: 03/18/04
Posts: 229
Loc: Burlington, Kansas
Ryan,
I disagree that the air is shoved out the end of larger pipes.
The suction part won't start until the air is out so that is a catch 22.
The 2" vent pipe on my ponds 12" pipe was set to low. The 12" pipe ran an awesome amount of water, but never a full pipe during a flood event where we had 20" of rain in 48 hrs or so. The pipe ran about 2/3 - 5/8 full on the discharge end while the pond was at spillway elevation. The 12" pipe had over 4' of head at that point. (about 8 psi)





Edited by zhkent (10/18/07 08:38 PM)
Edit Reason: added pic, link wasn't working
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#99467 - 10/13/07 09:36 AM Re: How Does the Pond Dam Piping SyponSystem Star [Re: zhkent]
rock creek Offline
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Registered: 06/27/05
Posts: 14
Loc: Kansas
Kent: I have set my 2 inch vent pipe at the level of the bottom of my 10 inch sypon pipe going thru the top of the dam. Based on your experience is this too low to allow the sypon action to start? It will not be difficult to raise the 2 inch vent pipe if I need to, but I would like to allow the sypon to reduce the pond level to the bottom of the syphon 10 inch pipe and shut off automatically at that level as the 2 inch allows air into the 10 inch pipe. Your thoughts are appreciated.

Rock Creek

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#99488 - 10/13/07 01:30 PM Re: How Does the Pond Dam Piping SyponSystem Star [Re: rock creek]
zhkent Offline
Lunker

Registered: 03/18/04
Posts: 229
Loc: Burlington, Kansas
Rock Creek,
My experience is that the draw down will not start a true siphon unless the vent pipe is the high enough to let out all the air.
The siphon will stop at this point as the water comes down.
The 10" pipe will continue to flow a lot of water without any siphon effect.
The next big rain will retest my system. It hasn't ran any water since repairing it.
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#99601 - 10/15/07 01:05 PM Re: How Does the Pond Dam Piping SyponSystem Star [Re: zhkent]
Jersey Offline
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Registered: 01/13/05
Posts: 469
Loc: Georgia
I have two 12" siphons with 4" vents. I have seen the vents a good 6" below the surface with a lot of water coming out the 12" pipes, but have never seen it actually siphon. I took to cap off of the tee in the vent so I could see straight down to the 12" pipe, and it had about 6-8" of water flowing over the bend. I am not sure why it didn't siphon.
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#99610 - 10/15/07 03:28 PM Re: How Does the Pond Dam Piping SyponSystem Star [Re: Jersey]
Ryan Freeze Offline
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Registered: 10/31/05
Posts: 1284
Loc: Southwest Ohio
If the vent is mounted near the highest point of the pipe, as the mainline fills, air will be pushed out the vent tube as long as the pressure at the open end isn't greater than it is on the inside opening...following the path of least resistance. Once the downhill side is completely filled with enough water on the downside that the weight of is greater than the weight of water it has to lift on the intake side, the siphoning starts, some remaining air left in the vent will be sucked back into the pipe (If the air volume inside the vent pipe is too much than it could potentially defeat the siphon) Assuming the vent is appropriately sized, during the siphoning, water should be getting pulled up through the vent. It will be part of the intake. The water filling the outlet pipe works like a plunger sliding down the pipe pulling water up the intake side. Once the water level drops below the vent intake, it will be easier to suck in air than water (again if the air vent is properly sized) The length and angle of the pipe on outlet side are going to have a major impact on the power and effectiveness of the system. The steeper and longer the downside of the pipe the more suction will be developed.
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#99651 - 10/15/07 08:36 PM Re: How Does the Pond Dam Piping SyponSystem Star [Re: Ryan Freeze]
zhkent Offline
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Registered: 03/18/04
Posts: 229
Loc: Burlington, Kansas
Water level has to be (1 1/2 the pipe diameter) higher than normal water level to run a full pipe of water with a conventional pond pipe that includes a canopy inlet.
This is optimum conditions to start suction and a pipe has to be submerged 1 and 1/2 times its dia. to start sucking and run a full pipe.
I wouldn't expect the siphon system to start running a full pipe as quickly, because of the incoming water having to pulled through piping and being less available.
I don't think air will be pushed anywhere out of the system. The pressure is on the pond side trying to push into both the vent and system. If the air can't go up it is trapped. The pressure on the pond side is not great enough to force a full pipe of water and purge the system on larger pipes.
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#99667 - 10/16/07 07:40 AM Re: How Does the Pond Dam Piping SyponSystem Star [Re: zhkent]
Ryan Freeze Offline
Lunker

Registered: 10/31/05
Posts: 1284
Loc: Southwest Ohio
zhkent & Jersey, do you have a trap on the outlet side of your systems? This is a key component if you want your siphon to start naturally, especially on the larger systems you have described. It traps water in the elbow at the bottom of the outlet side, allowing water to fill the downhill side of the pipe aiding in starting a siphon. Basically the same way your toilet works.



Edited by Ryan Freeze (10/16/07 08:10 AM)
Edit Reason: added drawing
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#99695 - 10/16/07 11:35 AM Re: How Does the Pond Dam Piping SyponSystem Star [Re: zhkent]
otto Offline
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Registered: 11/02/04
Posts: 1074
Loc: texas
Dear Rock Creek:
The answer to both your questions is yes. The water must go over the pipe and over the small vent pipe to start the syphon.

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#99754 - 10/17/07 06:15 AM Re: How Does the Pond Dam Piping SyponSystem Star [Re: Ryan Freeze]
rock creek Offline
Lunker

Registered: 06/27/05
Posts: 14
Loc: Kansas
Ryan: I am not sure what you refer to as a "trap" I have a 45 degree elbow at the bottom of my 10 inch pipe on the backside of the dam. I have approx 20 feet elevation difference between the intake in the pond and the end of the 10 inch on the backside of the dam. Assuming that the 2 inch vent pipe is set at the bottom of the 10 inch pipe, do you think this arrangement will be sufficient to start the syphon action when the water level of the pond is above the 10 inch pipe?

Rock Creek

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#99761 - 10/17/07 07:24 AM Re: How Does the Pond Dam Piping SyponSystem Star [Re: rock creek]
Ryan Freeze Offline
Lunker

Registered: 10/31/05
Posts: 1284
Loc: Southwest Ohio
You are correct that the elbow at the bottom forms your trap. It sounds likely you'll start to siphon when the water reaches above the pipe and could possibly even start a siphon when the pipe is half full. One of the siphon system manufacturers could tell you for sure at what point a siphon would start if you give them the full specs of your system.

Keep in mind it really isn't all that important to start a siphon unless you absolutely need the added capacity to remove excess water from your pond. You will still get the benefits of removing water from the bottom of the pond in contrast to a conventional overflow even if water is only trickling out.
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#99765 - 10/17/07 07:36 AM Re: How Does the Pond Dam Piping SyponSystem Star [Re: Ryan Freeze]
rock creek Offline
Lunker

Registered: 06/27/05
Posts: 14
Loc: Kansas
Ryan: Thank you for your thoughful and concise posts. It gives me confidence that, when needed, the syphon will prevent a big release down the emergency spillway. I also like the early ordinary flow but the real reason for the installation of the syphon is to protect the spillway and the pond from those huge rains we get here in eastern Kansas from time to time. When we have the right conditions to test the syphon, I will post and bring you and all the other posters on this thread with a "real time" update.

Rock Creek

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#99788 - 10/17/07 11:39 AM Re: How Does the Pond Dam Piping SyponSystem Star [Re: rock creek]
Ryan Freeze Offline
Lunker

Registered: 10/31/05
Posts: 1284
Loc: Southwest Ohio
Since you're in Kansas, is freezing water in the trap something to be concerned about?
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"The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge." Stephen W. Hawking

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#99798 - 10/17/07 02:23 PM Re: How Does the Pond Dam Piping SyponSystem Star [Re: Ryan Freeze]
BrianShpock Offline
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Registered: 08/24/07
Posts: 123
Loc: Drums, PA
Ryan,
I just got off the phone with EasyWay Plastics of Georgia in regards to the Syphon Piping and the potential of it freezing in the winter. I was informed the only reason for the trap is to prevent the water discharge from washing out the back of the dam.
They said you can use what ever angle pipe I prefer 45 Deg or 22.5 Deg. My concern was the pipe freezing if flow stops since there will always be water in the trap.
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