# How much air pressure is needed to push water up a column?

• Tsol
In summary, the person was looking for help creating a device that would use air pressure to move water up a tube. They attempted to create the device using buckets, but were not able to generate the needed pressure. They were wondering how much air pressure they would need and how much water above they would need to generate that pressure. They were also wondering if adding water to the right chamber would generate enough pressure to move the water up the tube.

#### Tsol

TL;DR Summary
Want to know how much air pressure is needed to raise water up a hose.
Hello,

I was creating a device to move water up a tube using air pressure, but I am not certain how much pressure I would need.

I attempted to create it using 5 gallon buckets, however I was unable to apply the needed pressure needed to the airtight container.

The image below is what I have in mind.
https://i.postimg.cc/5212GXWf/Untitled.png

I was wondering how much air pressure I would need and how much water above I would need to generate that pressure.

I was hoping that with something like 10 gallons of water I could move up 8 gallons or something. I know all 10 is unlikely, but am curious.How much pressure would I need to make water go up a small tube lets say 20 feet with a small tube diameter of like 5mm? And then how much water weight/height/ect would be needed to maintain that pressure?Thank you for your time and help in this matter.

Welcome to PF.

Air has a negligible density compared to water, so you can redraw your figure with the "pushing down" water on the right joined up with the "water column" on the left. The air chamber in this is irrelevant, IMO. The height of the water column on the left will be the same as the height of the "pushing down" water container on the right. Just draw a line across from the top of the water in the column on the left to the top of the water in the container on the right...

What is your application? What are you trying to do with this system?

I understand you are stating that the water will be at the same height on both sides no matter what the pressure is inside the airtight container.

I would have thought that the water (on the right) would have more force and push/compress the air so that it would push the water at the base of the airtight container up that tube higher than what it was originally at.

Such as for example adding in 10 gallons of water to the right would compress the air enough to move 5 gallons or some amount up the left tube higher than the water level on the right.

Possibly having the tank on the right be more like a large toilet tank where after x many gallons enter the system the lever/seal is opened on the bottom allowing water to flood in pushing/condensing the into a high enough pressure to get out the tube.

However, if you are stating that it doesn't/won't work like that then that's a bummer if that's the answer.The application was part of a system that if this part could be made to work the other parts would, but without this part working it's a moot idea.

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Sorry it's a bummer, but water seeks its own level. If you pump air into that central chamber, that pressure will raise both the left and right water levels equally. It sounds like that's what you found from your initial experiments, and didn't like the results. That's perfectly natural, and it's good that you are doing experiments to augment your book learning.

Yeah.

One last thought with this. Lets say the right water container sealed on the bottom opening like how a toilet would work, and after it fill up enough to lift the seal via a air balloon; couldn't the velocity/weight/ect of the water when the seal is opened allow the air to compress enough inside the central chamber?
Then like with a toilet tank when the water level drops to that lower point the seal would set back and rinse/repeat.

Thank you for your help on this :)

Tsol said:
Lets say the right water container sealed on the bottom opening like how a toilet would work, and after it fill up enough to lift the seal via a air balloon; couldn't the velocity/weight/ect of the water when the seal is opened allow the air to compress enough inside the central chamber?
Then like with a toilet tank when the water level drops to that lower point the seal would set back and rinse/repeat.
When the water system is opened, the left and right levels will change to equalize. You can add water in the right chamber above the left column height while your coupling valve is closed, but when you open the coupling valve, the two water levels will move to equalize their heights.

Kk,

Thanks for your help on this. Glad to have a solid answer saying it's not going to work the way I'm thinking. Was really hoping I could use this to move water up, but I suppose I'll have to find another method.Thanks again and stay warm out there!

berkeman
Tsol said:
Was really hoping I could use this to move water up, but I suppose I'll have to find another method.
Yeah, probably time to size some pumps.

Tsol said:
Thanks again and stay warm out there!
Thank you. Bundling up.

If you can seal the tank on the right and then pressureize it, the water in the tube will rise.

Of course you could get the same result by not having the right-side tank at all, just pressurize the sealed lower tank.

As a rough rule-of-thumb, for every PSI in the tank the the water will rise about 2 feet.

Cheers,
Tom

Tsol said:
TL;DR Summary: Want to know how much air pressure is needed to raise water up a hose.

How much pressure would I need to make water go up a small tube lets say 20 feet with a small tube diameter of like 5mm? And
It doesn't matter what size tube for the pressure at the bottom of the column. Column height matters, not diameter of the column

berkeman
hutchphd
I kinda have the same idea.but my idea works in a different way .I would also use a airtight tank.but my inflow would be a unequal communicating vessel. So that the water of the one side will push against the air pressure in the airtight tank . What will create an inflow and make the water rize inside the airtight tank, compressing the air inside the tank.by putting a vertical outflow pipe with his base below water level in the airtight tank.the compressed air will push the water out that pipe still need to test that setting.so I don't yet know how high it will push the water up.

That is the drawing of my idea

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kurt staelens said:
I don't yet know how high it will push the water up.
It will simply rise until it reaches equilibrium with the source tank.
That airtight container accomplishes nothing except to allow compression - which will partly negate the rise you're looking for.

You know what medium would be better than using compressible air? Incompressible water.

Eliminate the middleman in your pic and you are left with two communicating water tanks that will reach equilibrium. You won't do better than that by any passive means.

berkeman and russ_watters
@DaveC426913

from my point of view: because of the fact that the outlet of the communicating vessel is above water level inside the airtight tank. means that the airtight tank has no communication with my source. water pressure is proven to be stronger than air pressure.so the smaller tupe of the communicating vessel will create without a dought an inflow. because the tupe is higher than water level the only thing that will prevent the water from flowing out is the air pressure (inside the airtight tank) on the surface of that tube (this pressure will be higher than the pressure on the surface of the source ) but there is also weight of water higher then the outlet of the tube pushing down in the source. the fact that the water inside the airtight tank is lower than the inlet tube means there is no flow back.

what makes the only escape for the water inside the pressure tank is the outlet pipe. releasing the air pressure inside the tank to equality of the air pressure on the surface of the source. what makes the communicating vessel searching his equality again and create an inflow again. because of the second fact that the air pressure gets higher in side the tank than the air pressure on top of the outlet tube the water is forced up without any connection with the source. the only thing that can prevent the water from going up is the equality of the weight of water in the outlet tube against the air pressure inside the pressure tank what would create a back flow.so if i can stay lower than that point there will be also an out flow

Welcome to PF.

kurt staelens said:
from my point of view:
We do not allow discussion of Over-Unity Energy mechanisms at PF. That is in the Rules link (under INFO at the top of the page.

This thread will remain closed, since it seems to attract Over-Unity discussion attempts. What Dave said is the bottom line here:
DaveC426913 said:
It will simply rise until it reaches equilibrium with the source tank.

Bystander