Will a Siphon Function on the Moon?

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A siphon relies on gravity and atmospheric pressure to function, making it unlikely to work effectively on the Moon, where the atmosphere is nearly non-existent. The discussion highlights that without air pressure, the liquid in the siphon would not be pushed upward, leading to a vacuum and halting flow. The concept of negative pressure is introduced, suggesting that under certain conditions, a siphon could operate even in low-pressure environments, but typical liquids would not remain stable in a vacuum. The importance of hydrostatic pressure in driving liquid transfer is emphasized, indicating that a siphon would fail if the height exceeds atmospheric pressure limits. Overall, the consensus is that a standard siphon would not function in a vacuum, such as that found on the Moon.
  • #31
cjameshuff said:
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 spacecraft 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..
 
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  • #32
threadmark said:
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:

threadmark said:
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.


threadmark said:
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.


threadmark said:
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.


threadmark said:
And to answer your question” What is a reveres airlock” to have an airlock in space is to exit a spacecraft 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.


threadmark said:
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.


threadmark said:
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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