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Author Topic: The self-filling siphon, and why can't it be done?  (Read 62956 times)

broli

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Re: The self-filling siphon, and why can't it be done?
« Reply #45 on: July 21, 2009, 03:27:45 PM »
Coincidently I had two types of tubes laying around. One is double the diameter of the other. I stuck the small one in the big one and started the experiment.

Unfortunately the results aren't positive. It will siphon when the outlet is below the water level in the reservoir but once it's above it the siphon action stops and the water rushes back to the tank. There's no question about being more water on the down side. As I made sure the connection of the tubes is at the highest point.

Below you see the setup and the position of the outlet where the siphon action takes place.

Nabo00o

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Re: The self-filling siphon, and why can't it be done?
« Reply #46 on: July 21, 2009, 03:39:19 PM »
Bah, oh well I was afraid it would be like that, even if I don't know what is causing it!
You are sure that the thickness of the outlet pipe didn't allow air bubbles to go in?
Probably this isn't the case, so there is something else going on here, but I wonder what...
Btw, in that picture the outlet pipe isn't perfectly vertical, this could at least cause minor problems...

Naboo

broli

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Re: The self-filling siphon, and why can't it be done?
« Reply #47 on: July 21, 2009, 03:52:40 PM »
Bah, oh well I was afraid it would be like that, even if I don't know what is causing it!
You are sure that the thickness of the outlet pipe didn't allow air bubbles to go in?
Probably this isn't the case, so there is something else going on here, but I wonder what...
Btw, in that picture the outlet pipe isn't perfectly vertical, this could at least cause minor problems...

Naboo

The experiment was pretty controlled. The pipe on one side held at least 190+% more water, so there's no question about more water in the bigger tube. And There was no air since I started from a siphon location and gradually moved the pipes up so the outlet was above the water level. But once I reached the water level the siphon action stopped and the remaining water rushed back to the reservoir.

I encourage you to perform this experiment yourself as its simple and you can see what happens for yourself.

Nabo00o

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Re: The self-filling siphon, and why can't it be done?
« Reply #48 on: July 21, 2009, 07:50:54 PM »
Well I have tried it now and got the same results as you, actually I also tried a while ago before I started this tread but I believed that something else was giving the bad results. Seem like the idea of disproportional weights in a siphon isn't that easy after all to initiate. So, as best we can tell hydrostatics seems to be all-prevailing law in siphoning as well, but maybe we can learn from this.

I'm not ready to give up this topic yet because we also discussed capillary action here, and maybe it does have the potential to unlock the secrets of unlimited flow, against gravity. Maybe there could be a way to combine siphoning with capillary action, maybe that was the secret the Russians used. I want to know more about that! :D

Also, the user craZy reported some very interesting results with his experimentation. If this actually happened I do believe this needs to be investigated more throughly...

Naboo

sm0ky2

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Re: The self-filling siphon, and why can't it be done?
« Reply #49 on: July 22, 2009, 06:43:15 AM »
hmm......

Cloxxki

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Re: The self-filling siphon, and why can't it be done?
« Reply #50 on: July 22, 2009, 08:54:28 AM »
hmm......
I wish that would work. The top outlet is an air inlet, though.

exnihiloest

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Re: The self-filling siphon, and why can't it be done?
« Reply #51 on: July 22, 2009, 10:33:42 AM »
hmm......

It will not work: water in the pipe on the right will be sucked up and siphoned into the pipe at the center. There will be no water in the right container.

onthecuttingedge2005

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Re: The self-filling siphon, and why can't it be done?
« Reply #52 on: July 22, 2009, 04:21:33 PM »
A pycnometer or specific gravity bottle is a flask with a stopper that has a capillary tube through it, which allows air bubbles to escape. The pycnometer is used to obtain accurate measurements of density.

lowering the boiling point of liquids always helps.
if that was Liquid Nitrogen in the pycnometer is would come out with a violent pressure reaction.

Jerry ;)

onthecuttingedge2005

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Re: The self-filling siphon, and why can't it be done?
« Reply #53 on: July 22, 2009, 04:39:42 PM »
It will not work: water in the pipe on the right will be sucked up and siphoned into the pipe at the center. There will be no water in the right container.

Hi exnih.

you are right, it will act like this Robinair High Vacuum Valve.

Jerry

Nabo00o

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Re: The self-filling siphon, and why can't it be done?
« Reply #54 on: July 22, 2009, 04:57:26 PM »
@all
Even though that setup smokey showed probably doesn't work you shouldn't dismiss it so fast.
To see if it really works or what it does you need to see both how the momentum of the water could affect it and also how the vectors work, if the different vectors add together or if they work against each other.

@onthecuttingedge2005
In your opinion, what would the best available structure or material be for a homemade capillary tube?
I ask because I want to do some serious experimentation in this area, as I've already seen, it seems like slightly different materials have very different properties. As you surely agree the biggest nut to crack then is how to make the water flow out of it again.
Do you have any ideas or suggestions? Thanks!

Naboo

Nabo00o

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Re: The self-filling siphon, and why can't it be done?
« Reply #55 on: July 22, 2009, 05:01:02 PM »
Oh damn, I got the best Idea in I've had in a while now!!!!
This can get interesting....

Edit: Siphons in most (probably all setups) are governed by hydrostatics.
What I did in those drawing was to reverse the place the water's weight rested on, now they instead hanged in the roof, but then all that weight/suction power got absorbed (just like in normal hydrostatics).
But, what if that water hanged directly from the output of a capillary tube????
(think before you speak :D)
Naboo

Edit yet again: This is damn interesting!

onthecuttingedge2005

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Re: The self-filling siphon, and why can't it be done?
« Reply #56 on: July 22, 2009, 05:12:52 PM »

@onthecuttingedge2005
In your opinion, what would the best available structure or material be for a homemade capillary tube?
I ask because I want to do some serious experimentation in this area, as I've already seen, it seems like slightly different materials have very different properties. As you surely agree the biggest nut to crack then is how to make the water flow out of it again.
Do you have any ideas or suggestions? Thanks!

Naboo

try researching it with low boiling point Alcohol instead of water. I think the solution is the boiling point of the liquid medium breaking the capillary surface tension via pressure.

here is a Mercury fountain that uses Mercury's low boiling point.
http://www.youtube.com/watch?v=B1FnF5zUPEE

Jerry ;)

Nabo00o

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Re: The self-filling siphon, and why can't it be done?
« Reply #57 on: July 22, 2009, 05:23:16 PM »
I think the solution is the boiling point of the liquid medium "breaking the capillary surface tension via pressure."
Dead on!
I'll try to show some sketches soon. It will also show just why my setup didn't work and why we can overcome that problem!

Julian

onthecuttingedge2005

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Re: The self-filling siphon, and why can't it be done?
« Reply #58 on: July 22, 2009, 05:36:46 PM »
You might try something like this.

Jerry ;)

Nabo00o

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Re: The self-filling siphon, and why can't it be done?
« Reply #59 on: July 22, 2009, 09:09:44 PM »
I'm not sure exactly how that works, well I'm not yet that experienced with capillary structures.
Anyway here's my idea to why my previous theory didn't work. Basically it was all the time a hydrostatic system, it had just been reversed. Instead of making the fluid rest on the ground and thus making its weight equally compensated for, it now hanged from the roof so to say, and thus its weight will be compensated for by the structure it is hanging from. It is is really just like turning the a normal hydrostatic example upside down, and then you are working with negative pressures instead of positive ones.

I made these examples just to show my thinking, the ones to the left are the purely theoretical ones, while the ones to the right are made to handle the air-bubble problem when you increases the surface of a pipe or container too much. I think this also explains siphoning pretty well, you are working hydrostatic pressures as in any normal container with an outlet, but instead of working with positive pressures you are working with negative ones. (if that makes sense):