Alien Invasion - I want my pond back !

[4570Man]

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.

I think they proved a siphon will not work in a vacuum, because there is no liquid to siphon in a vacuum.

 

[aczlan]

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

 

[SPYDERLK]

Ok, that vacuum video WAS very cool!

So tell me if either of these posits should be true:

Assumption 1 & 2: identical cohesion and viscosity of two liquids of different densities... (maybe neither matter?)

Posit 1) If gravity is the primary outside force acting on a siphon... A more dense liquid should flow through a given siphon faster than a less dense liquid.

Posit 2) If atmospheric pressure were the primary outside force... The less dense liquid would flow faster. (Or density makes no difference?)

I have some confidence that posit 1 is true. Less confident about posit 2.
I also think viscosity would change rate of flow but cohesion probably only has to exceed some minimum requirement for a given atmospheric pressure (to prevent cavitation and bubbles forming.

Thoughts? Hopefully that made at least some sense.

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.

Petrol is less dense than water. Siphoning a jerry can of petrol into my boat tank seems to work reasonably quickly. My intuition is that its faster than water.

Unfortunately, the viscosity of gas is much less than H2O. Viscosity should be the main determining factor of 'resistance' (not density).
The other factor would be adhesion between the fluid and the tube. But I think adhesion would be a very small effect with any tube diameter over a few millimeters.

I think these posts are mostly cohesive.
,,, We should dispense with the idea that atmospheric pressure is the primary or even necessary force for flow. ... but does atmospheric pressure establish a condition that enables a siphon to exist? ... or does its absence in whole or part present a limitation?

,,,To my mind, this ionic liquid presents a "trick" that makes it difficult to sort necessary issues. ... It is a liquid that is being displayed in a way that suggests it has tensile strength. UH-h, but it pours, right? So something in its tensile strength has to do with it being held to shape and size by being in a tube. It has great cohesion to itself, but what holds it out to the tube? ... Suppose we fill a tube in a reservoir then lift the middle of the tube. What is the height that the tension in the liquid pulls it away from the tube? Does this not depend on air pressure?
,,,,,,,larry

 

[Xfaxman]

Siphon Sock

A siphon doesn't have to be in a tube or pipe.

Here is my Siphon Sock to remove rain water from the brush hog deck. I have used rags on things like this for many years.

 

[SPYDERLK]

Re: Siphon Sock

A siphon doesn't have to be in a tube or pipe.

Here is my Siphon Sock to remove rain water from the brush hog deck. I have used rags on things like this for many years.

Capillary attraction ... like a wick.

 

[Kyle_in_Tex]

Re: Siphon Sock

Capillary attraction ... like a wick.

Capillary action is a very strong force.

 

[Xfaxman]

Re: Siphon Sock

Capillary attraction ... like a wick.

Capillary action is a very strong force.

Yep, but slow.

9:29 AM

7:52 PM

 

[k0ua]

Not many people would think to use a smelly old sock to empty a bucket!:laughing:

 

[Eric Salop]

Great practical demo Xfaxman :thumbsup:



Two Weeks In
Another week had gone by and that water level had kept on falling all the time. It was now almost down to the filter in the sump.



Time to get the spade out and dig the sump a little deeper. While I was in digging mode, I set to and deepened the narrow channel leading from sump towards the centre of the pond. I also added an extra length of pipe to the outlet. This really got the water moving, almost overflowing the bucket despite the 2" hole in the side.




Water slide
Everything has it's consequences. Speeding up the water flow had helped move a lot of water overnight and sucked out a deeper hole in the bottom of the sump. It had also eroded away grass and soil below the bucket. No problem, simply lay an even bigger sheet of plastic on the surface. There were dozens of baby newts under the old sheet. They had been using that pipe as a giant water slide and were now trying to work out how to get back up for another ride.

We have 3 types of newt in the UK. One of them is supposed to be rare in Europe (we have plenty around here). This is what the government says about anyone disturbing them :-
You could be sent to prison for up to 6 months and be fined 5,000 ($7,500). I'm sure you wouldn't want me to be put away for 6 months, or anyway, not until after we get to the aliens, so I'll play safe and leave out newt pics.


Filter Mark 2
Within a day the sump was dry. With another extension pipe on I walked the filter box out to the deeper water over on the far side and came back to the bank, only to find the extension had pulled free. I waded back to put it back on, but couldn't find the filter. Returning with a spade, I set up a wider search pattern. How can you loose a box that size ? I found a few cans and bottles, corrugated metal sheet and even a children's pink bicycle, but I never found that wooden box again. My wife thought this was funny and unbeknown to me snapped pictures of me searching and wearing a very puzzled What the heck is going on expression.



It ran ok for a short while without the filter, but then kept getting blocked in the mud. Out came the reserve filter. An ex-washing machine drum. Very effective.

All gone
Some time that following week the siphon ran dry for the final time. Gravity may have taken it's time, but it had willingly worked day and night for free, almost without a break.

 

[RedNeckGeek]

Hurray and well done!:dance1::thumbsup:

Were alien spawn discovered at the bottom of the drained pond?