Alien Invasion - I want my pond back !

[MossRoad]

Can anyone find a picture or example of a siphon where the downhill side of the siphon is shorter than the uphill side? If so, please post it.... thanks!

 

[Eric Salop]

A Week Later

At last the week at work was finally over and I could get back to the pond and play.

The drive over the moors from Yorkshire was always enjoyable, but never filled with so much anticipation as while trying to clear out this pond. After the M62 multi lane highway leaves the busy outskirts of Manchester, the much quieter A49 starts to wind it's way through Cheshire and a landscape dominated by dairy farming. As the twisting road gently rises and falls on it's way to Shropshire, time seems to slow down, the hectic pace of the last few days is soon forgotten and thoughts return to how the siphon had got on. I could have increased my speed a little to arrive a few minutes earlier, but that wouldn't make any difference to the water level in the pond. The siphon had either worked or it hadn't, simple as that. If it hadn't worked, well there was still plenty of time for another try if need be.


I need eye glasses to drive, but I certainly did not need glasses to see that the pond had changed. The excess water over the normal summer level had gone and bare ground was starting to appear part way down the bankside. Shallows to the side of the sump looked more like an estuary at the turn of the tide than a farm pond.

Various wildlife had been to visit the emerging shoreline and see what was going on. All had left little prints behind in the mud, with the badgers sinking in the deepest.


Before I left the previous week I had pushed in a measuring stick, intending to take before and after pictures. This is how it looked after just over a week of draining.

The original level is not easy to see on the white and orange stick. If you look to the far bank, you can see how far the level had dropped by the weed left hanging on the bushes that were previously skimming the surface of the water.



Over the next couple of days, I had nothing much do, apart from cleaning the filters. The chicken netting filter on the sump had done a great job.

I had another length of pipe ready go further down the hill and so increase the flow rate, then the "If it ain't broke don't fix it" mentality kicked in. This time I wasn't quite so apprehensive as I left it to continue at it's steady pace for another week.

 

[SPYDERLK]

So you're saying a 10' long downhill pipe with an outlet 1" below the inlet of a 100' long uphill pipe will work?

Until a bubble collects at the apex.

 

[SPYDERLK]

Can anyone find a picture or example of a siphon where the downhill side of the siphon is shorter than the uphill side? If so, please post it.... thanks!

Long gradual rise on uphill, then steep drop to a lower level on down side. ... A geometry issue.

 

[Redneck in training]

So you're saying a 10' long downhill pipe with an outlet 1" below the inlet of a 100' long uphill pipe will work?

It depends. The total lift can't be more than what atmospheric pressure at the location can push up (about 10 m or 32.8 ft max). The flow at 1" head will be very low.

 

[the old grind]

I agree with Larry and RIT. :thumbsup:

Neither leg carries the full weight of water unless that leg is vertical. (pressure determined by distance below the surface) It doesn't matter where the high point in a siphon is, or comparative horizontal length(s) of the legs. (A vector issue?) Pressure at the low end of a 100' pipe with 1' total rise will be the same as at the low end of a 1' vertical one. (btw, diameter 'don't mean squat')

Once air is removed from a siphon water will flow to the lower source's level until they equalize, hunches and pipe length(s) aside. Bubbles/entrained air, pipe dia/friction, and mass of the water in the siphon will affect flow rate only. It's easy to be confused by vertical vs horizontal (TDH) displacement and water weight, but mechanical devices rely on science vs superstition. tog

I once saw a 2nd floor waterbed drained via garden hose with its outlet a good 10' below the bag. ~ 10lb of 'suction'. Man did that baby drain fast and pucker up at the end of the job.

 

[SPYDERLK]

I agree with Larry and RIT. :thumbsup:

Neither leg carries the full weight of water unless that leg is vertical. (pressure determined by distance below the surface) It doesn't matter where the high point in a siphon is, or comparative horizontal length(s) of the legs. (A vector issue?) Pressure at the low end of a 100' pipe with 1' total rise will be the same as at the low end of a 1' vertical one. (btw, diameter 'don't mean squat')

Once air is removed from a siphon water will flow to the lower source's level until they equalize, hunches and pipe length(s) aside. Bubbles/entrained air, pipe dia/friction, and mass of the water in the siphon will affect flow rate only. It's easy to be confused by vertical vs horizontal (TDH) displacement and water weight, but mechanical devices rely on science vs superstition. tog

I once saw a 2nd floor waterbed drained via garden hose with its outlet a good 10' below the bag. ~ 10lb of 'suction'. Man did that baby drain fast and pucker up at the end of the job.

The added flow situation is that in low flow siphons, air sucked out of the water slowly collects at the hi point and will finally stop the siphon.

 

[Luke'sScreenName]

Come on Eric! KEEP GOING! These other guy are going to start a fire rubbing their sticks together! When I was in academia we called that 'mental matsurb@tion.' Fun for you but not for anyone else and it never gets you anywhere but where you're at.

 

[fordmantpw]

A Week Later

At last the week at work was finally over and I could get back to the pond and play.

The drive over the moors from Yorkshire was always enjoyable, but never filled with so much anticipation as while trying to clear out this pond. After the M62 multi lane highway leaves the busy outskirts of Manchester, the much quieter A49 starts to wind it's way through Cheshire and a landscape dominated by dairy farming. As the twisting road gently rises and falls on it's way to Shropshire, time seems to slow down, the hectic pace of the last few days is soon forgotten and thoughts return to how the siphon had got on. I could have increased my speed a little to arrive a few minutes earlier, but that wouldn't make any difference to the water level in the pond. The siphon had either worked or it hadn't, simple as that. If it hadn't worked, well there was still plenty of time for another try if need be.


I need eye glasses to drive, but I certainly did not need glasses to see that the pond had changed. The excess water over the normal summer level had gone and bare ground was starting to appear part way down the bankside. Shallows to the side of the sump looked more like an estuary at the turn of the tide than a farm pond.

Various wildlife had been to visit the emerging shoreline and see what was going on. All had left little prints behind in the mud, with the badgers sinking in the deepest.


Before I left the previous week I had pushed in a measuring stick, intending to take before and after pictures. This is how it looked after just over a week of draining.

The original level is not easy to see on the white and orange stick. If you look to the far bank, you can see how far the level had dropped by the weed left hanging on the bushes that were previously skimming the surface of the water.



Over the next couple of days, I had nothing much do, apart from cleaning the filters. The chicken netting filter on the sump had done a great job.

I had another length of pipe ready go further down the hill and so increase the flow rate, then the "If it ain't broke don't fix it" mentality kicked in. This time I wasn't quite so apprehensive as I left it to continue at it's steady pace for another week.

That's a rather drastic change in just a week. Great progress!

Oh, and your writing had me in anticipation, just like your drive did!

 

[RedNeckGeek]

I once saw a 2nd floor waterbed drained via garden hose with its outlet a good 10' below the bag. ~ 10lb of 'suction'. Man did that baby drain fast and pucker up at the end of the job.

I've had the same experience draining various waterbeds located in second story bedrooms. Even had a waterbed maintenance kit that came with a venturi based siphon starter. The device connected to a faucet and had a port on the side for a garden hose. The other end of the garden hose connected to an adapter that fastened to threads on the waterbed. The faucet was turned on and the venturi drew water from the mattress to fill the hose, and even if the waterbed was lower than the faucet, continue to drain the mattress, but rather slowly. To save water I'd pinch the hose closed at the faucet by folding it over, disconnect it from the venturi, then carry it outside where the kink was opened allowing the siphon to start. If it was a second story bedroom, I'd let as much hose as possible out the window before letting go of the kinked end, and the siphon would start immediately and flow strongly.

I also use a siphon tube regularly to remove fuel from various tanks around this place. This particular tube has a built in check valve consisting of a ball that is allowed to move freely between a seat and a stop along the length of the tube. This check valve is about an inch or so long, and located near one end of the tube. The check valve end of the tube is submerged in the fluid to be transferred and the user shakes the tube along its length. The ball seats at the fluid side, locking fluid into the tube as it moves above the surface, and when the tube returns into the fluid the ball unseats and allows air to escape so that the fluid advances up the tube. Just keep shaking until the fluid reaches the open end, hold a thumb over the end of the tube until the open end is lower than the fluid surface, then release the thumb to start the siphon. No more fuel in the mouth!

Probably wouldn't have been possible to shake a tube the size of Eric's, but given a well equipped shop, it wouldn't have taken much to rig a sealing disk that fit the tube ID that had a similar check valve mounted somewhere on its surface. Attach the disk to a broom handle, shove it up the tube, and start pumping.

Agreed, it's the difference in level that exists between the high and low end of the siphon that moves the water. While a higher high point in the middle will make filling the tube more of a challenge, once accomplished the flow rate depends only on the height difference between the two ends of the tube and not on the distance or gradient between them. As the weather warms, all that's needed to verify this for yourself is a length of clear vinyl tubing, a bucket of water, and something on which to perch it. Put the tube into the bucket until if fills with water, then put a thumb over one end and move it to a level below that of the water in the bucket. Experiment with the height of the middle high point and the gradient of the tube and verify that as long as the end is lower when the thumb is released, the siphon will start. Experiment with the height difference between the tube ends and verify that the greater the difference, the higher the flow rate. Use different diameter tubes and observe the increased flow rate. Make a video of all this on YouTube and become the latest Internet fad!

Now all that's left to be done is lighting a fire under Eric so we can all learn how long it took his pond to empty, hopefully without waiting for weekly installments. Otherwise at least some of the subscribers to this thread (including me), will unsub and just come back this time next year to finish the story... :laughing: