Siphon in a vacuum?

  • Thread starter Steve B
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ok ,I am not to good with words. If I had a capsule half filled with water, then vacuum the air from the top of the capsule to the structures maximum pressure threshold(any more would collapse the structure).could water be taken from the capsule without affecting the structure. An example would be when you drink from a plastic bottle sealing your lips over the opening. As you draw flexing your mouth to get it full it collapses the structure of the bottle because of the elasticity of thin plastic. Could you extract water from the capsule? The point I’m making is you can siphon water from a vacuum and the definition in the dictionary does not conflict with this process. You can convey through immersion and if you look up immersion it doesn’t denote to needing air pressure at all. For argument sake, the cup of water could be submerged before the vacuum is present. Then simply put the cup in a reverse airlock through the means of robotics if you wish and seal the R airlock and quench your thirst. All of these actions do not conflict with what the oxford English dictionary defines as a siphon. I have just siphoned a cylinder of water from the vacuum through immersion and conveying. the structure could collaps after the cup had been removed but I still siphoned a glass of water from a water exempted vacuumed capsule. Using the 99 year old definition.
 
  • #27
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I quote from my 11th edition concise Oxford English dictionary at home.
 
  • #28
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Increase or decrease, it makes no difference. Vacuum is vacuum, there's nothing there to push or pull on the walls of the vessel. Obscure things like the Casimir effect aside, vacuum exerts no force, positive or negative, no matter what the volume.




Just a note, if you increase the vacuumed structures dimensions whilst in vacuum. It would void the integrity of the structures ability to hold a vacuum. So if I increase the dimensions of the structure wouldn’t I theoretically change its volume irrelevant to it becoming void? I say this as I wait for some more info on this dictionary correction montage to help me understand where they went wrong with definition of siphon. Please give the dictionary edition that this mistake took place. If it helps to correct my misunderstanding i read this from a concise oxford dictionary (11th edition). Please correct my confusion.
 
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  • #29
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threadmark,

Look at Steve B's original post in this thread. The definition at issue is the one you can find by going to the link in his post;

http://tinyurl.com/2cfghd5

which re-directs to this article in The Sydney Morning Herald;

http://www.smh.com.au/entertainment...oes-unnoticed-for-99-years-20100510-uoh2.html

The portion of the definition which is in error is where it says that a siphon operates "by means of atmospheric pressure, which forces the liquid up the shorter leg and over the bend in the pipe"

In fact, a differential hydrostatic pressure (between the two vertical legs of the siphon) is what makes a siphon operate. Such a pressure difference is both necessary and SUFFICIENT for a siphon to work.

The dictionary entry is NOT trying to describe factors (such as atmospheric pressure) which can affect the operation of a siphon... it is asserting that atmospheric pressure CAUSES a siphon to flow... WRONG!

Dr. Hughes is not "splitting hairs" when he insists that the publishers of "The Oxford English Dictionary" should correct the entry.

We have enough trouble in this world resulting from scientific ignorance among the non-science community... we need to agressively address the correction of "bad science" whenever we encounter it...

The higher the "authority" of the source - the more credible the erroneous assertion becomes - and the more importance we should attach to the effort to correct the error.

.
 
  • #30
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ok ,I am not to good with words. If I had a capsule half filled with water, then vacuum the air from the top of the capsule to the structures maximum pressure threshold(any more would collapse the structure).could water be taken from the capsule without affecting the structure. An example would be when you drink from a plastic bottle sealing your lips over the opening. As you draw flexing your mouth to get it full it collapses the structure of the bottle because of the elasticity of thin plastic.
No. The bottle collapses because of the external air pressure and the lack of countering pressure from inside. As I've said before, there is no pressure from a vacuum.


Could you extract water from the capsule? The point I’m making is you can siphon water from a vacuum and the definition in the dictionary does not conflict with this process. You can convey through immersion and if you look up immersion it doesn’t denote to needing air pressure at all. For argument sake, the cup of water could be submerged before the vacuum is present. Then simply put the cup in a reverse airlock through the means of robotics if you wish and seal the R airlock and quench your thirst. All of these actions do not conflict with what the oxford English dictionary defines as a siphon. I have just siphoned a cylinder of water from the vacuum through immersion and conveying. the structure could collaps after the cup had been removed but I still siphoned a glass of water from a water exempted vacuumed capsule. Using the 99 year old definition.
Again with the reverse airlock, and with structures collapsing. Can you describe just what, exactly, a "reverse airlock" is? And what could possibly cause a container containing nothing, surrounded by nothing, to collapse? What is the source of the forces on its walls causing it to collapse, when there's nothing on either side of them?


Just a note, if you increase the vacuumed structures dimensions whilst in vacuum. It would void the integrity of the structures ability to hold a vacuum.
As I've explained in detail, no, it wouldn't. It takes no structural integrity to hold a vacuum in vacuum. None. The forces on the walls of the structure are precisely zero, no matter the changes in volume you make.


So if I increase the dimensions of the structure wouldn’t I theoretically change its volume irrelevant to it becoming void?
What does "Irrelevant to it becoming void" mean?
You'd change its volume, yes. That's not theory, it's reality, there's numerous ways of making structures that change in volume. The part you keep missing is that when vacuum is concerned, it doesn't matter what the volume is.

It is as tyroman said. Air pressure will support the fluid in the connecting tube and allow that tube to rise to a greater hight before breaking the fluid column, but it acts on both ends of the tube, and has nothing to do with moving fluid through the siphon.
 
  • #31
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No. The bottle collapses because of the external air pressure and the lack of countering pressure from inside. As I've said before, there is no pressure from a vacuum.




Again with the reverse airlock, and with structures collapsing. Can you describe just what, exactly, a "reverse airlock" is? And what could possibly cause a container containing nothing, surrounded by nothing, to collapse? What is the source of the forces on its walls causing it to collapse, when there's nothing on either side of them?




As I've explained in detail, no, it wouldn't. It takes no structural integrity to hold a vacuum in vacuum. None. The forces on the walls of the structure are precisely zero, no matter the changes in volume you make.




What does "Irrelevant to it becoming void" mean?
You'd change its volume, yes. That's not theory, it's reality, there's numerous ways of making structures that change in volume. The part you keep missing is that when vacuum is concerned, it doesn't matter what the volume is.

It is as tyroman said. Air pressure will support the fluid in the connecting tube and allow that tube to rise to a greater hight before breaking the fluid column, but it acts on both ends of the tube, and has nothing to do with moving fluid through the siphon.

You are not making sense in your observations; “there is no pressure from a vacuum”. I did not state there is pressure in a vacuum, I am pointing out the fact that putting a capsule in vacuum is a structural dependant action. And if you don’t understand that let me break it down. If you vacuum a capsule you could keep vacuuming until it implodes. But besides that, to siphon liquid is not dependant on air pressure. The definition also states to immerse a tube. Look up siphon in the oxford dictionary then we can have a discussion about how to siphon water in a vacuum.
And to answer your question” What is a reveres airlock” to have an airlock in space is to exit a space craft without compromising the air in the space craft. so to have a reverse airlock I thought would be to exit a vacuum without compromising the vacuum.
And to say a vacuum is not pressure dependant is silly in this context because its put forward there is a capsule involved and that pressure would be relevant even though I didn’t say it is pressure dependant. You stated “ The bottle collapses because of the external air pressure and the lack of countering pressure from inside”
I’m sorry but this would make pressure relevant..
 
  • #32
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You are not making sense in your observations; “there is no pressure from a vacuum”. I did not state there is pressure in a vacuum,
You stated a container in vacuum would implode if the volume of vacuum inside it were increased by drawing a liquid out with a siphon:

if you want to siphon the fluid out of the bath tub into the vacuumed room, it’s not a problem. But if you try to siphon the fluid out of the room it’s impossible because there is no space to fill the void. The vacuum is proportionate to the volume of the room. if you take something out you increase the volume. if you increase the volume whilst in vacuum the room would implode.

I am pointing out the fact that putting a capsule in vacuum is a structural dependant action.
That statement has no meaning. The phrase "is a structural dependant action" does not make sense.


And if you don’t understand that let me break it down. If you vacuum a capsule you could keep vacuuming until it implodes.
What could cause a container in vacuum to implode? Implosion implies that an inward force is being applied to the structure of the container...by stating that this would happen, you are claiming that a vacuum exerts pressure.


And to answer your question” What is a reveres airlock” to have an airlock in space is to exit a space craft without compromising the air in the space craft. so to have a reverse airlock I thought would be to exit a vacuum without compromising the vacuum.
That's just an airlock, there's nothing reversed about it.


And to say a vacuum is not pressure dependant is silly in this context
No, it's just another meaningless phrase. Those words do not have meaning when put together in that way.
Freezing is pressure dependent, boiling is pressure dependent, vacuum is a state of zero pressure and absence of matter...it depends on nothing.


because its put forward there is a capsule involved and that pressure would be relevant even though I didn’t say it is pressure dependant. You stated “ The bottle collapses because of the external air pressure and the lack of countering pressure from inside”
I’m sorry but this would make pressure relevant..
This was in response to a remark you made about sucking water from a plastic bottle. You're not in vacuum, the bottle is not in vacuum, the fact that the bottle collapses is entirely irrelevant to the discussion about siphons in vacuum.

You seem extremely confused about pressures and vacuum in general. The question you asked in another thread, "Isn’t the act of a vacuum to exert all possible mass whilst maintaining the structure the vacuum resides in?", simply makes no sense...to start with, mass isn't something that's exerted, and a vacuum doesn't exert anything. Once again, a vacuum is just an absence of matter. Aside from relatively tiny effects like photon pressure and the Casimir effect, a vacuum exerts precisely zero force...there's nothing there to exert force. There's nothing there to change properties based on volume, there's no pressure. You don't need "space to fill the void".

Out in the open here on Earth, reducing pressure in a container with insufficient structural strength to support the outside atmospheric pressure will cause the container to implode. Put it in a vacuum chamber, and you can draw a vacuum in even the flimsiest container without it imploding. If that vacuum chamber can support an atmosphere of external pressure, it doesn't matter how many vacuum pumps you hook up to it or how good they are, it won't implode. Once the air has been removed, the interior is a vacuum, and that's that.
 

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