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Author Topic: How does a siphon work?  (Read 88305 times)

Offline Andrew K Fletcher

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How does a siphon work?
« Reply #75 on: 25/10/2008 19:14:33 »
Nice try SophieCentaur. But you fail to address the fact that the water volume between the two plates of glass has a massive number of molecules that do not come into contact with the glass and stretch from the molecules that do. So if the two plates of glass are stuck together it is not just because of adhesion is it? If you agree with this, then you must also accept that cohesion in this experiment is = to the adhesion, because this has been used to state the strength of adhesion.
 

lyner

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How does a siphon work?
« Reply #76 on: 25/10/2008 19:24:30 »
UH?
You have a chain which breaks. One of the middle links is weaker than the rest. You do an experiment to determine the relative strengths and, low and behold, you choose to say that one of the stronger, end, links broke first.
That just doesn't make sense to me.
Whilst you have some tension then all the links are holding. When the weaker links break, the chain breaks.
Do you contest the evidence of the shape of a meniscus which implies that the adhesion is stronger than the cohesion?
Did you learn any Science (or even some logic) at School, or did you reject it even then?

« Last Edit: 25/10/2008 19:36:56 by sophiecentaur »
 

Offline Andrew K Fletcher

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How does a siphon work?
« Reply #77 on: 25/10/2008 20:34:44 »
http://www.imss.fi.it/vuoto/eberti.html#


Experiment by Gaspare Berti in the Minim Convent at Pincio.
Gaspar Schott, Technica curiosa, sive, Mirabilia artis, WŁrzburg 1664

Three and a half centuries ago, most scientists didn't believe in the concept of a vacuum, or a place with no air. But there were a few renegade researchers including Gasparo Berti, who set out to make a vacuum. Berti rigged up a huge glass tube, several stories high alongside his house, and filled the tube with water. Then he sealed off the top of the tube and opened the bottom into a pail full of water. He found that the water level in the tube dropped a few feet, but then didnít move. Berti claimed that he had produced a vacuum in the tube above the water line, and thatís just what he did. He also made a barometer by gosh, but he didnít realize it, so it was no big deal. But a couple years later, a guy named Torricelli after carefully eyeing Bertiís vacuum thingamajig, set out to make a barometer with mercury instead of water, because Bertiís barometer was just too big. The experiment was a success, and Torricelli became the creator of the barometer. So, a classic mercury barometer is only about 2 1/2 feet high and much easier to deal with than Bertiís water barometer which would be about the size of your average house. So, on a beautiful spring day, if you used Bertiís barometer, the pressure would read about 30 feet, instead of 30 inches.

The Weather Notebook is underwritten by Subaru, the beauty of all wheel drive with major support by the National Science Foundation. http://www.weathernotebook.org/transcripts/1998/01/30.html

« Last Edit: 25/10/2008 21:09:16 by Andrew K Fletcher »
 

lyner

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How does a siphon work?
« Reply #78 on: 25/10/2008 21:04:48 »
Nice picture - was it a holiday snap?
But what about my questions? They actually contain some serious Science.
p.s. Yet again you don't read your own links. It was a LEAD siphon. Adhesion to metals would be very low so even your tube experiment wouldn't work at >10m.
You could always try to repeat it with lead, I suppose. A tenner says it wouldn't have the same result as for your plastic tube.
« Last Edit: 25/10/2008 21:09:14 by sophiecentaur »
 

Offline Andrew K Fletcher

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How does a siphon work?
« Reply #79 on: 25/10/2008 21:11:09 »
Im beginning to Like you SophieCentaur :)
 

lyner

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How does a siphon work?
« Reply #80 on: 25/10/2008 21:19:52 »
Love you too! Mwah.
Now for an answer?
 

Offline Andrew K Fletcher

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How does a siphon work?
« Reply #81 on: 25/10/2008 22:44:57 »
Ok so back to the two sheets of glass. If as you suggest cohesion is the weakest link. Then this test never did address the adhesion of water but showed the cohesion of water. Because there would be a huge amount of molecules between both sheets of glass that do not come into contact with the glass.

Now, if we sandwich two sheets of steel together with water between them do we again feel a similar bond between them. As someone who has worked in sheet metal, I can confirm that there is adhesion between the plates, as to whether it is similar to that of glass I cannot remember as itís been many years ago now. But certainly remember struggling to part wet steel sheets and stainless steel sheets too.
 

lyner

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How does a siphon work?
« Reply #82 on: 26/10/2008 00:07:55 »
Your experiences with sheet steel and  glass are not relevant because you did no measurements and could not have distinguished quantitatively between attraction or pressure. There is no evidence one way or another there.

How could the sheets of glass have been stuck together if there weren't both cohesion and adhesion? How could the test distinguish between the strengths of the two? A chain of 100 links or a chain of one link would each have the same strength (cohesion). The fixings at either end (adhesion) are just as important, though. You have no knowledge whether the chain or the fixings failed first without side information about the relative strengths.
Does the simple meniscus test not mean anything to you regarding the relative bonding forces? You keep avoiding answering that question. Why?

Is a rubber band solid or liquid? Is it a proper analogy to describe how the siphon works? The 'chain' analogy certainly doesn't either - it can only be used in the context of the 'glass plates and, even then, only in a dynamic sense.

Try thinking Science this time instead of wanting to be right. Stop shifting your ground all the time and concentrate on these few key issues.
Once they are sorted out we can move on, perhaps.
« Last Edit: 26/10/2008 08:39:01 by sophiecentaur »
 

Offline Andrew K Fletcher

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How does a siphon work?
« Reply #83 on: 26/10/2008 08:34:55 »

Air & Water by Mark Denny Pages 255 266 deals with what Professor Hammel mentions in his letter. H.T. Hammel was a World Authority on circulation in trees, spending many years researching it, and a fascinating man who also worked on nuclear energy. We had some interesting conversations regarding cohesion, one of which was the spinning Z tube, and itís commercial application.
http://books.google.co.uk/books?id=XjNS6v7q130C&pg=PA255&lpg=PA255&dq=spinning+z+tube+cohesion+water&source=web&ots=sGiBMDOEe6&sig=1DfEAi94WVJoGQlzM7-MNwUgjEY&hl=en&sa=X&oi=book_result&resnum=1&ct=result#PPA256,M1

Water flowing vertically in a single open ended tube to 24 meters using salt as the driving force.

Introduction to the experiment
 

Bench top scaled down version of the Brixham Experiment

Andrew K Fletcher


 

lyner

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How does a siphon work?
« Reply #84 on: 26/10/2008 10:11:32 »
why are we back on trees?
Whenever things get tight you start off in another direction. I'm quite happy to talk about trees when we've cleared up the crucial issue of you understanding the logic of my last post. No one else's input is needed for that.
 

Offline Andrew K Fletcher

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How does a siphon work?
« Reply #85 on: 26/10/2008 11:46:26 »
We are not. Denny relates to cohesion and adhesion which is where we are at.
Read the two pages please, it answers your questions about cohesion and adhesion
 

lyner

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How does a siphon work?
« Reply #86 on: 26/10/2008 13:00:36 »
But I need YOU to answer the questions. You see, I don't think you understand my questions (or much of the stuff you keep quoting as answers).
 

Offline Andrew K Fletcher

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How does a siphon work?
« Reply #87 on: 26/10/2008 16:40:42 »
You first dispute tension is possible. It is proved that it has been measured. Then you dispute the stregnth of cohesion stating ashesion is stronger. Again the measturements of cohesion speak for themselves.

Then there is the evidence of a droplet of water on a surface, rising up from the surface against gravity. Nothing to stick to here is there? Unless you count water sticking to the atmosphere that is.
 

lyner

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How does a siphon work?
« Reply #88 on: 26/10/2008 21:05:26 »
Just where is the evidence which "speaks for itself". Where is the measurement of cohesion compared with the measurement of adhesion?
Where else but in the simple meniscus in a water tube?
Could you please comment on what the curve of a meniscus tells you about the relative strengths of the cohesive and adhesive effects? Do you actually understand any of this?

When does a droplet 'rise up' out of the water without being given some kinetic energy? Yet again, you bring up another issue and do not stick to the main one.
What has this to do with your understanding of the meaning of the two terms you keep using and have not yet defined or described.
 

Offline Andrew K Fletcher

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How does a siphon work?
« Reply #89 on: 26/10/2008 21:57:08 »
The way to settle this is for you to conduct your single six mil bore capped tube elevated vertically above the 10 meter mark and come back and let us all know how it goes. Trying to get me to jump through your hoops is a little lame.

What does the meniscus tell us? It relates to surface tension much more than adhesion. The same can be seen with a water boatman on a pond causes a clear depression in the surface. Do we conclude that the whole of the pond has rose up above the feet of the water boatman? Are you presuming that the curve shows water being pulled up the tube? If so then consider the atmospheric pressure pushing the water up the tube by pressing down on the water that the tube rests in.

You keep asking if I understand your reasoning. The answer is I understand that your reasoning about the ten meter mark that you teach from your science books is erroneous. The Brixham experiment was with a single open ended tube, stretched vertically to 24 metres and more. A tiny amount of salt causes water to flow around the tube drawing water from one vessel into another, and you have the cheek to tell me I do not know my subject. Go explain the Brixham experiment to your students and let them see that the 10 meter limit does not ring true.

You try to separate this flow and return system into boxes so it can be challenged in a way that you can deal with it. Well, this is not how this theory was born. It was born from reading a tremendous amount of open ended conclusions that still to this day attract a tremendous amount of arguments. The Cohesion tension theory as it stands to date is complete Bull***t. Why protect your students from truth?

The meniscus curve does not show water climbing out of the open ended tube now does it? Capillary action does not move water over half a meter does it? What about capillary action in a six mil bore tube for a start off, where does this leave adhesion?

And while we are at it, please explain why varicose veins go flat when a bed is tilted head up by five degrees to the horizontal.

You see SophieCentaur. I know that this theory holds water! I have seen the effects of IBT, which is based on this theory reversing spinal cord injury, multiple sclerosis, cerebral palsy, Parkinsonsís Disease, varicose veins, oedema, thrombosis, scarletina, blindness, and many more conditions. So please refrain from thinking this is some whimsical fantasy.  There is a lot at stake for a lot of people and all the time I have to deal with sanctimonious condescending people who think having a qualification places them in a position to ridicule and ostracise a real scientist working on the cutting edge of science and delivering repeatable results.

If you canít handle this then that is your problem and you have to deal with it not me.
 

lyner

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How does a siphon work?
« Reply #90 on: 26/10/2008 22:28:35 »
We'll have to leave it at that then.
When you learn some Science rather than a list of partially related instances, you may realise what I am talking about.
We usually find that people without respect for qualifications are those who have very few of their own.
 

Offline Andrew K Fletcher

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How does a siphon work?
« Reply #91 on: 27/10/2008 08:33:46 »
I don't have qualifications. I am not a doctor either. But I do have a an enquiring brain and use it to great effect questioning traditionally unsubstantiated guesswork .
Who else is qualified in reversing spinal cord injury and all those other illnesses that respond because a flat bed is avoided? Where are the peers when a discovery is new and contradicts the established views in science?

You put down a challenge for me to test my own theory, yet are unwilling to test your own theory about why the Brixham experiment works and would rather try to mock someone who has tested his own theory experimentally to see if it not only causes water to flow vertical to more than twice the accepted limit, and cause it to hang in mid air with both ends of the tube open to the atmosphere.

My research is challenging your teachings.

I can handle constructive criticism. But will not have you or anyone else try to belittle me. Save that skill for your pupils education and see how many become scientists.


We'll have to leave it at that then.
When you learn some Science rather than a list of partially related instances, you may realise what I am talking about.
We usually find that people without respect for qualifications are those who have very few of their own.
 

lyner

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How does a siphon work?
« Reply #92 on: 27/10/2008 10:10:00 »
If you look at the preceding posts you will see that it was not I who started with disparaging remarks. You have 'belittled' the well thought out theories of Scientists who have good track records and you have impugned my teaching. I have merely replied to criticism in kind. If you don't like that sort of thing then don't start it.

It is not up to me to 'prove' anything. I have been trying to apply one or two extremely well established ideas in order to explain your experiences.   My argument with you is that your 'explanations' for a list of phenomena are just not rigorous. I tried to reduce one issue (adhesion vs cohesion) to the least complex level. That is not intended to be disparaging to you; it is just the way one needs to approach Science when one want to improve understanding.
You have clearly not seen the relevance of my questions about how your ideas relate to the most basic models in Science. The ideas I am working with are tried and tested (involving molecules, bonds, pressure, stress etc.). They work very well in other contexts so they can be expected to work in this context too.

What you have failed to grasp is that, if your model and explanation of the way water behaves in one specific situation, were correct then water would behave very differently in many other situation. You have not acknowledged the paradox. This can either be because you just don't know basic Science or that you feel so beleaguered that you are not prepared to look outside of the box.

The only way to overturn a hitherto successful scientific theory is to understand it thoroughly and then to see where it is wrong. If your ideas were really correct then you should be able to 'see where I am coming from' and explain my error in my terms. Instead, you have avoided the crux of my questions.
If I haven't expressed myself well enough then there are are plenty of textbooks which can, no doubt, put it better.

Your arguments just don't include rigour; they diverge, rather than converge on an issue. Because of this, they fail to convince.

Until you understand the existing models and all their implications more thoroughly then you are not in a position to justify your own.
Do you think that Einstein would have avoided an argument involving Newtonian Mechanics? He knew he was right with SR and GR because he understood the previous work fully and could see where it was inadequate. He could explain the content of the previous theories in terms of his new theories because he was thoroughly grounded in his subject. Where is your grounding and where does your theory take you with respect to the existing theories?

The theories about molecular attraction are not, by the way, 'unsubstantiated guesswork'.
« Last Edit: 27/10/2008 14:53:59 by sophiecentaur »
 

Offline Andrew K Fletcher

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How does a siphon work?
« Reply #93 on: 04/11/2008 09:34:41 »
Adhesion in water depends on cohesion, it cannot function without cohesion. Cohesion does not need adhesion to work. Water molecules are attracted to each other whether in a rain drop falling from the sky, in the ocean, or indeed a tree.
 

Offline Bored chemist

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How does a siphon work?
« Reply #94 on: 04/11/2008 19:39:47 »
Is it just my imagination, or is Andrew obsessed with trees?
Perhaps he was a dog in a previous incarnation
 

Offline Andrew K Fletcher

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How does a siphon work?
« Reply #95 on: 04/11/2008 20:30:49 »
Imagination BC, there ain't no past life, this is a science forum.
Is it just my imagination, or is Andrew obsessed with trees?
Perhaps he was a dog in a previous incarnation
 

Offline Bored chemist

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How does a siphon work?
« Reply #96 on: 04/11/2008 22:05:41 »
OK, there's no evidence for a past life but I think I can find some evidence about trees.
 

Offline Andrew K Fletcher

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Re: How does a siphon work?
« Reply #97 on: 01/02/2012 20:17:51 »
Successfully operating a siphon in a vacuum, using an exotic ionic liquid that can handle the extreme conditions.

 

Offline Bored chemist

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Re: How does a siphon work?
« Reply #98 on: 01/02/2012 21:57:16 »
Successfully operating a siphon in a vacuum, using an exotic ionic liquid that can handle the extreme conditions.


So?
 

Offline CliffordK

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Re: How does a siphon work?
« Reply #99 on: 01/02/2012 23:28:50 »
I thought it was interesting.  But, not surprising.  However, they obviously did not have a perfect vacuum either.

So, my question is.

What is the limit of the height of a siphon with an ionic liquid?

With Mercury, the maximum height of a siphon is 760mm, or 1 ATM.
With Water, the maximum height of a siphon is theoretically 33.95 feet (also 1 ATM).

Does vapor pressure also play a role?  So a siphon of water at 99įC would be a lot lower than one at 4įC.

With the ionic liquid, I assume one could likely calculate the maximum height of the siphon based on the density of the liquid.  So, if the density was around 13.5 g/cc, then the maximum height of the siphon would be about 760mm.

If the density was about 1g/cc, then the maximum height would be about 34 feet.

In the You-Tube film, I would be curious what they would have gotten had they used a loop of material giving a height of about 3 feet or so.
 

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Re: How does a siphon work?
« Reply #99 on: 01/02/2012 23:28:50 »

 

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