# Is it possible to have water levels at different heights without a pump?

• StefanBoon
In summary, an air lock is a situation where the pressure of the air above is not equal to the pressure of water at the surface. This can prevent a siphon effect from occurring.
StefanBoon
I wonder if air can remain trapped under a structure that has a deep and a shallow tube. I have already tested with a prototype whether increasing volume in the shallower tube works. Air bubbles came out on the short side, so this doesn't work. Is there any way to realize this concept.

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The quick answer to your question is no, but it is worth spending some time thinking about why.

Think about the forces acting on the water right at the surface: if the downwards pressure from the air above is not exactly balanced by the upwards pressure from the water immediately underneath, the level will either fall (air pressure is greater) or rise (water pressure is greater). What can you say about the air and water pressures above the two tubes?

StefanBoon
Nugatory said:
The quick answer to your question is no, but it is worth spending some time thinking about why.

Think about the forces acting on the water right at the surface: if the downwards pressure from the air above is not exactly balanced by the upwards pressure from the water immediately underneath, the level will either fall (air pressure is greater) or rise (water pressure is greater). What can you say about the air and water pressures above the two tubes?
Thank you, very much appreciated. What do you mean with the last sentence 'What can you say about the air and water pressures above the two tubes?'

Do you mean that it can work if the pressures of the air above is the same as de water at the surface of the short tube?

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StefanBoon said:
I wonder if air can remain trapped under a structure that has a deep and a shallow tube.
First of all I have to point out a very basic fact that it is not the diameter of the pipe that affects pressure - just the height of the vertical column.

I'm not sure if the image is the exact layout where what you describe happens (or doesn't happen) It sounds as if you are describing what's known as an 'Air Lock'. In a situation where there is air in an inverted U, the 'bubble' of air can be longer than the differences in the two water levels. The section of trapped air floats and supports the water columns so you don't get a simple siphon effect. (Plumbers come across this problem all the time where there are long horizontal runs of pipe in low pressure systems.

Practical Note: your drawing shows a flat horizontal surface at the bottom of the upper section. This is not stable and one side or the other will fall after a very short time. You would need a free moving piston to keep that water surface flat and level. You need narrow tubes to make this work.

StefanBoon and Lnewqban

## 1. Can water levels be at different heights without a pump?

Yes, it is possible for water levels to be at different heights without a pump. This phenomenon is known as the siphon effect.

## 2. How does the siphon effect work?

The siphon effect works by utilizing the principles of gravity and atmospheric pressure. When a tube or pipe is filled with water and one end is placed in a higher position, the weight of the water in the higher end creates a vacuum that pulls the water from the lower end up and over the curve of the tube, allowing it to flow upwards.

## 3. What are the limitations of using a siphon for different water levels?

The height difference between the two water levels is limited by the atmospheric pressure. Generally, the maximum height difference for a siphon to work is around 10 meters. Additionally, the diameter and length of the tube also play a role in the effectiveness of the siphon.

## 4. Can a siphon work with any type of liquid?

Yes, the siphon effect can work with any type of liquid, as long as it is able to flow freely through the tube. However, the density and viscosity of the liquid may affect the speed and efficiency of the siphon.

## 5. Are there any risks or dangers associated with using a siphon?

Yes, there are some risks associated with using a siphon. If the tube is not properly sealed or if there is a break in the tube, air can enter the system and disrupt the siphon. Additionally, if the siphon is used to transfer hazardous or toxic liquids, there is a risk of exposure if the tube breaks or leaks. It is important to handle and use siphons carefully and with caution.

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