Alien Invasion - I want my pond back !

[dave1949]

That pretty cool Eric. Well done!

See any sign of Jimmy Hoffa? :laughing:

 

[MossRoad]

Interesting video but it doesn't prove that a siphon will work in a vacuum in my opinion. They are not using 'water'. They are using an ionic liquid, a type of 'liquid magnet' as they explain it. So its more akin to using a chain in a vacuum, and of course a chain will respond to gravity. They are not really creating a siphon at all.

My guess is that a true siphon really does use air pressure to push water up the tube. The air pressure at the lower end is not important. The low pressure is created by gravity INSIDE the tube as the water tries to separate from itself, hence creating a vacuum or suction inside the tube. So a true siphon requires atmospheric pressure AND gravity.

Your saying siphons blow and science says they suck...

 

[MossRoad]

The long rise side is like an ideal inclined plane - frictionless. Gravity acts proportional to the sine of the angle. ... Less than 1 on the rise, but 1 on the vertical fall.
...Any fall greater than the rise will flow to the fall.

Have you gotten out your clear hose two buckets and a camera yet? Would love to see your results.

 

[MossRoad]

In my experience, a siphon doesn't care about the slope on either end or the amount of hose under water. It just cares that the discharge end is below water level and the further below water level the discharge end is, the more flow comes out of the discharge.

Aaron Z

You're absolutely correct. However, the question is can the uphill side of the hose be longer than the downhill side of the hose from the top of the water level?

 

[SPYDERLK]

Have you gotten out your clear hose two buckets and a camera yet? Would love to see your results.

No you wouldnt because they would just support physics.
,,, Prove it to yourself. If it doesnt work post good pictures and Ill tell you what you did wrong.

 

[aczlan]

You're absolutely correct. However, the question is can the uphill side of the hose be longer than the downhill side of the hose from the top of the water level?

As long as the total fall is greater than the total rise and the outlet is lower than the water level it should siphon water.

Aaron Z

 

[alchemysa]

Well I must admit I'm surprised at how fast its draining.

But now I'm really looking forward to the bogged tractor pics.

 

[MossRoad]

As long as the total fall is greater than the total rise and the outlet is lower than the water level it should siphon water.

Aaron Z

Exactly! What's pretty revealing is to take two glasses of water, put a water filled clear plastic tube into them and then lift one up and watch it fill the other, then lift the other and watch it go back. Note that the upstream side of the hose is always shorter than the downstream side as measured from the level in the containers. As you mention, the length of hose under the level of the fluid is irrelevant.

Here's yet another video showing how it works. :laughing:

https://www.youtube.com/watch?v=CZmP0vsRBZ8

 

[MossRoad]

No you wouldnt because they would just support physics.
,,, Prove it to yourself. If it doesnt work post good pictures and Ill tell you what you did wrong.

I've given numerous examples to support my position. You've given none. :dance1:

 

[4570Man]

I went outside and tested this, and I was surprised with the result. The up side was 15-1/2 feet long, and the down was 7-1/4 long. I ended up with a wet driveway, and an empty Yeti.

 

[MossRoad]

I went outside and tested this, and I was surprised with the result. The up side was 15-1/2 feet long, and the down was 7-1/4 long. I ended up with a wet driveway, and an empty Yeti.

Finally some proof. Thank you for testing. I am surprised too.

 

[MossRoad]

As long as the total fall is greater than the total rise and the outlet is lower than the water level it should siphon water.

Aaron Z

It appears I'm confusing rise with distance.

 

[MossRoad]

I went outside and tested this, and I was surprised with the result. The up side was 15-1/2 feet long, and the down was 7-1/4 long. I ended up with a wet driveway, and an empty Yeti.

Curious how you started the siphon.

 

[4570Man]

Curious how you started the siphon.

I tried to just suck on it, but I was unable to suck hard enough. I used a piece of vinyl tubing to help seal it, and held a water hose on the downhill side. When I heard water flowing into the tank I removed the water hose, and the water started flowing the other direction.

 

[MossRoad]

I tried to just suck on it, but I was unable to suck hard enough. I used a piece of vinyl tubing to help seal it, and held a water hose on the downhill side. When I heard water flowing into the tank I removed the water hose, and the water started flowing the other direction.

I was wondering, as I thought I saw another tube on the ground. Thanks. I'll give it a try as soon as it stops raining! I'll have plenty of water in my pool cover tomorrow! :thumbsup:

 

[RedNeckGeek]

I went outside and tested this, and I was surprised with the result. The up side was 15-1/2 feet long, and the down was 7-1/4 long. I ended up with a wet driveway, and an empty Yeti.

Water always seeks the lowest level.

Except here in Kalifornia, where it runs uphill to money :shocked:

Thanks for doing the test and clearing the air, 4570.

 

[SPYDERLK]

The downhill side always has to be longer than the uphill side AND the discharge always has to be lower than the inlet. If its not, it will try to flow the wrong way.

The downhill side does not have to be longer ... only to discharge at a lower level.
,,,larry

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.

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

What is going to pull water up the hill? There is more weight on the uphill side than the down hill side. It absolutely will not work.

The long rise side is like an ideal inclined plane - frictionless. Gravity acts proportional to the sine of the angle. ... Less than 1 on the rise, but 1 on the vertical fall.
...Any fall greater than the rise will flow to the fall.

Have you gotten out your clear hose two buckets and a camera yet? Would love to see your results.

No you wouldnt because they would just support physics.
,,, Prove it to yourself. If it doesnt work post good pictures and Ill tell you what you did wrong.

I've given numerous examples to support my position. You've given none. :dance1:

Here ya go.

 

[Eric Salop]

Excavating the gloop next, but before we say goodbye to siphons, I will try and clear up a few points that have been raised (RedNeckGeek, this could be real boring, you may want to skip and come back tomorrow).

I see a lot of fun debate going on about what people think would work and wouldn't work with a siphon. To me, nothing beats getting out a bit of plastic tubing and having a play. The beauty of siphons is that everything you try with a small bit of tubing will also scale up to larger diameter and longer pipes. The only limitation I know of is that the maximum vertical height is supposed to be 33 feet. I was near that limit when I put on the last extension piece and was half expecting trouble, but it ran well. At more than 33ft they say a vacuum is created at the top of the down flow pipe - hey anyone for a water powered vacuum pump project ?

I have watched many youtube siphon videos and although some of them are very good, some of the classroom style presentations leave a lot to be desired in my opinion. Siphons are not chains running over a pulley. You would miss out on a lot if that's how someone teaches you to think about siphons. Chains run over a pulley to the lowest point for the same simple reason that everything in the universe moves - they are lazy. Give any inanimate object the chance to get to a lower energy state and it will grab that opportunity in the easiest way it can. The physicists amongst you will correct me if I am wrong, but that is about the only thing chains and water siphons have in common.

Turbines
The outflow can be used to turn a turbine, but you may want to do a little calculation first to see how much power you can generate and decide if it is worthwhile.

Any liquid that is free to move will run downhill. In that respect water moving through a siphon is no different, it is simply getting rid of some of it's "Potential Energy". You can calculate how much potential energy it can loose by the classic
equation.

Potential Energy = m * g * h
m = Mass of water moved
g = acceleration due to gravity
h = Difference in height from the level in the pond to the bottom of the discharge pipe.

Most people calculate this using SI units, so m would be measured in kilograms and h in metres. Unless you have been abducted by aliens to another planet, g is near enough a constant figure of 9.8 metres per second per second.

So when 1 kg of water is siphoned over a height of 1 m, it looses it's potential energy of :-

1 kg * 9.8 * 1 m = 9.8 Joules


With a small diameter tube that takes 10s to drain the kilogram of water, the power is

9.8 Joules / 10s = 0.98 Watts

If a turbine and generator was 100% efficient (they are nowhere near that in reality, but let's ignore that for the moment), we could convert that head of water into an electrical output of 0.98 W for a whole 10s.


Alternatively, we could use a bigger tube and perhaps move it all in a single second.

The power is then 9.8 J / 1s = 9.8 W

That sounds 10 times more impressive, however it only lasts for a single second, then all the water is gone. The energy availabe is constant regardless of how fast we draw off the water.


How far horizontally can a siphon go ?
As long as the source is higher than the outlet, you have scope to move any fluid in the direction you want with a siphon, over inches or even miles. Water doesn't care if the pipe twists left and right or up and down along the way.

All that happens with long runs is that friction in the pipe slows the water flow and so increases the time it takes to move the water.


Where does that energy go ?
The water rubs up against the wall of the pipe, raising very slightly the temperature of the water and the pipe. The pipe then in turn very slightly heats the outside air.

There is always a little bit of turbulence inside the pipe, so that warms the water a little too.

When the water hit the stones on the outflow from my yellow bucket, the stones and water heat up, eventually passing on this heat energy to the air and ground. This accounts for the bulk of the m*g*h lost.
The newts could have soaked up a little bit of that heat too.

In fact, by the time the water has soaked into the ground, it has almost stopped moving, so there is almost no resultant kinetic energy left in the water as it percolates into the ground.

Almost forgot - I could hear the water splashing over the stones, so a tiny bit was converted to sound.




Siphon summary

Gravity is your friend - get the outlet to the lowest point possible for fastest flow.

Air is your enemy - keep it out of the pipe.

Air pressure can be a useful ally - fit a bucket, or u bend, on the end if you want to keep it primed while restricting the flow.

Filters are fussy - don't use unless you have to. If needed, think carefully about how fast they will block.

Obstructions are to be avoided - don't get the sucking end blocked up, keep it in free water. Ideally, use a pipe diameter wider than the fattest water vole



Next Time
Enough of siphons, time to get digging.

 

[SPYDERLK]

Excavating the gloop next, but before we say goodbye to siphons, I will try and clear up a few points that have been raised (RedNeckGeek, this could be real boring, you may want to skip and come back tomorrow).

I see a lot of fun debate going on about what people think would work and wouldn't work with a siphon. To me, nothing beats getting out a bit of plastic tubing and having a play. The beauty of siphons is that everything you try with a small bit of tubing will also scale up to larger diameter and longer pipes. The only limitation I know of is that the maximum vertical height is supposed to be 33 feet. I was near that limit when I put on the last extension piece and was half expecting trouble, but it ran well. At more than 33ft they say a vacuum is created at the top of the down flow pipe - hey anyone for a water powered vacuum pump project ?

I have watched many youtube siphon videos and although some of them are very good, some of the classroom style presentations leave a lot to be desired in my opinion. Siphons are not chains running over a pulley. You would miss out on a lot if that's how someone teaches you to think about siphons. Chains run over a pulley to the lowest point for the same simple reason that everything in the universe moves - they are lazy. Give any inanimate object the chance to get to a lower energy state and it will grab that opportunity in the easiest way it can. The physicists amongst you will correct me if I am wrong, but that is about the only thing chains and water siphons have in common.

Turbines
The outflow can be used to turn a turbine, but you may want to do a little calculation first to see how much power you can generate and decide if it is worthwhile.

Any liquid that is free to move will run downhill. In that respect water moving through a siphon is no different, it is simply getting rid of some of it's "Potential Energy". You can calculate how much potential energy it can loose by the classic
equation.

Potential Energy = m * g * h
m = Mass of water moved
g = acceleration due to gravity
h = Difference in height from the level in the pond to the bottom of the discharge pipe.

Most people calculate this using SI units, so m would be measured in kilograms and h in metres. Unless you have been abducted by aliens to another planet, g is near enough a constant figure of 9.8 metres per second per second.

So when 1 kg of water is siphoned over a height of 1 m, it looses it's potential energy of :-

1 kg * 9.8 * 1 m = 9.8 Joules


With a small diameter tube that takes 10s to drain the kilogram of water, the power is

9.8 Joules / 10s = 0.98 Watts

If a turbine and generator was 100% efficient (they are nowhere near that in reality, but let's ignore that for the moment), we could convert that head of water into an electrical output of 0.98 W for a whole 10s.


Alternatively, we could use a bigger tube and perhaps move it all in a single second.

The power is then 9.8 J / 1s = 9.8 W

That sounds 10 times more impressive, however it only lasts for a single second, then all the water is gone. The energy availabe is constant regardless of how fast we draw off the water.

Good. -- I like to keep the Joule = Watt-sec or W= J/s in my head. Helps clarify Energy vs Power

 

[Eric Salop]

The Dig is Off

It was early September 2006 and everything had been going well so far. The siphon had worded a treat and the steady draining had taken care of any groundwater.

The intention was to dig within a few days of emptying and not give rain any chance to undo all the good work. A machinery company based less than 2 miles away was set to hire me a 20 ton tracked excavator and two, 6 ton wheeled dumper trucks. I would drive one of the dumpers and two friends, both experienced with heavy equipment, would drive the others.

Sometimes things don't go to exactly to plan and sometimes life is plain cruel, turning everything upside down. My wife was down to annual check-ups, so many now that each one had become almost a formality, except for that one in 2006. Cancer had returned and she was immediately taken in for surgery. There would be no thoughts of digging in the foreseeable future.