Great demonstration! Interesting to see how the water column separation occurred right at the valve on the PVC pipe, and the vapor pocket formed further down the line with the steel pipe. You should have installed a high frequency pressure transducer at the valve to record the pressures and compare between both pipes.
Kind of… it depends - Water hammer does not depend on pressure to form but water hammer itself is a pressure shockwave. What I mean by that is - the water pressure in a pipe can be anything, even zero (pipe half empty scenario), water hammer doesn’t care about pressure as it’s CAUSE but it really cares about the speed of the water traveling through the pipe… The water hammer is formed because water is not a compressible substance (relatively speaking) just like a metal… When water travels through a pipe, it stores kinetic energy equivalent to its momentum (speed) and the volume of water in any given cross-section of the pipe (wide pipe is a lot of heavy water vs. tiny pipe is a little heavy water). So when a valve is quickly closed, regardless of the pressure of the water in the pipe at the time of the valve’s closing, the fast-moving water crashes into the closed valve and the entire column of water moving behind it doesn’t simply stop, it also crashes into the back of that water at the valve, which forms a pressure shockwave that is called the water hammer itself, because there is nowhere for the water to dissipate it’s kinetic energy except for itself, the valve, and the pipe… so this shockwave just keeps traveling down the pipe until all of the water in the pipe has stopped. The faster the water is moving and the more of it there is in a pipe (or the longer the pipe is), the stronger the water hammer will be… if you have a ton of fast moving water in a very long pipe, that is a whooole lot of kinetic energy to dissipate… so if a valve is suddenly shut, regardless of the pressure before the valve is shut, there will definitely be pressure after it is shut due to all of that rushing water having to stop all the way down the pipe. However, the above only applies to water stopping when a valve is shut… not when a valve is opened. The following point is also noteworthy: If we are talking about a valve opening and water beginning to move, then the pressure does matter… the reason why is because if there is a lot of pressure in a pipe and it is suddenly released into a section of a pipe with less pressure, that pressurized water will be able to flow very fast… and thus, it can also create water hammer if that rushing water comes crashing into a bend or a valve… similarly, once the empty part of the pipe fills up with water, the same effect will occur, all of the fast rushing water now must crash into itself and come to a stop, which will create water hammer… So the point is, pressure matters but doesn’t matter… the real kicker is usually the volume and speed of water that has to stop in a pipe.
Jay shwaz Check your solenoid or pneumatic water valves first. There is probably one causing the problem. Took forever to find the one causing my headache.
I thought it was going away from the camera, towards the horizon. When she opens the valves the bubbles just go in that direction. Or I got completely wrong?
@Lucas this was my impression as well. The air vents only make sense if the hammer effect in question is happening on the outlet water - and it is, you can see that the vents are immediately after the valves - because they work by letting outside air relieve the vacuum formed by water flowing away from the closed valve. They do not relieve fluid pressure; if that were the case, water would gush out from the vents when the valve was closed (it spills when the valve is reopened, but that's just the vent's check valves closing). In this particular scenario, the closing of the valve stops the inlet water flow (which also produces a hammer effect in the back pipe, but it's probably designed with that in mind) and the water flowing away from the valve creates a vacuum which pulls the water column back, smashing at the valve. The air vents are there to allow air to flow in and prevent this from happening.
Water (or gas) is moving inside the pipe. If you close the pipe quickly, the moving water has nowhere to go, so they basically press into the end of the pipe, creating a region of very high pressure. Think of it like hundreds of people running inside a narrow tunnel. Imagine what happens if you close the exit suddenly. Then it rebounds, traveling backward in the pipe then forward again then backward, so on and so forth. Hence a water hammer, because it sounds like a series of loud bangs. This can cause serious damage (the pipe would literally burst) and is highly dangerous in certain situations.
Great demonstration! Interesting to see how the water column separation occurred right at the valve on the PVC pipe, and the vapor pocket formed further down the line with the steel pipe. You should have installed a high frequency pressure transducer at the valve to record the pressures and compare between both pipes.
thank you. your demonstration make me good understand the effect of water hammer.
Thanks guys, very useful!! This help to understand the water hammer effect much better.
At 45 seconds she says" And now I am going to turn the air vents OFF.. BUT SHE TURNS THEM "ON".
Wow Ted you must be a really smart guy to point out the obvious
Demonstration was awesome!
Thanks 🙏
Nice video.
It is not water air separation , it is forming of water vaper bubbles due to partial cacuum created in the pipe line.
The best demonstration in all youtube
Is water hammer less of a problem at lower pressures? Thanks.
Kind of… it depends -
Water hammer does not depend on pressure to form but water hammer itself is a pressure shockwave.
What I mean by that is - the water pressure in a pipe can be anything, even zero (pipe half empty scenario), water hammer doesn’t care about pressure as it’s CAUSE but it really cares about the speed of the water traveling through the pipe…
The water hammer is formed because water is not a compressible substance (relatively speaking) just like a metal…
When water travels through a pipe, it stores kinetic energy equivalent to its momentum (speed) and the volume of water in any given cross-section of the pipe (wide pipe is a lot of heavy water vs. tiny pipe is a little heavy water).
So when a valve is quickly closed, regardless of the pressure of the water in the pipe at the time of the valve’s closing, the fast-moving water crashes into the closed valve and the entire column of water moving behind it doesn’t simply stop, it also crashes into the back of that water at the valve, which forms a pressure shockwave that is called the water hammer itself, because there is nowhere for the water to dissipate it’s kinetic energy except for itself, the valve, and the pipe… so this shockwave just keeps traveling down the pipe until all of the water in the pipe has stopped.
The faster the water is moving and the more of it there is in a pipe (or the longer the pipe is), the stronger the water hammer will be… if you have a ton of fast moving water in a very long pipe, that is a whooole lot of kinetic energy to dissipate… so if a valve is suddenly shut, regardless of the pressure before the valve is shut, there will definitely be pressure after it is shut due to all of that rushing water having to stop all the way down the pipe.
However, the above only applies to water stopping when a valve is shut… not when a valve is opened.
The following point is also noteworthy:
If we are talking about a valve opening and water beginning to move, then the pressure does matter… the reason why is because if there is a lot of pressure in a pipe and it is suddenly released into a section of a pipe with less pressure, that pressurized water will be able to flow very fast… and thus, it can also create water hammer if that rushing water comes crashing into a bend or a valve… similarly, once the empty part of the pipe fills up with water, the same effect will occur, all of the fast rushing water now must crash into itself and come to a stop, which will create water hammer…
So the point is, pressure matters but doesn’t matter… the real kicker is usually the volume and speed of water that has to stop in a pipe.
Can this air vent be used in a factory on the main water supply?
Jay shwaz Check your solenoid or pneumatic water valves first. There is probably one causing the problem. Took forever to find the one causing my headache.
Where can I buy the air vent? Thank you
In which direction is the water flowing?
Bima C. Bhaskara It's flowing towards the camera.
I thought it was going away from the camera, towards the horizon. When she opens the valves the bubbles just go in that direction. Or I got completely wrong?
@Lucas this was my impression as well. The air vents only make sense if the hammer effect in question is happening on the outlet water - and it is, you can see that the vents are immediately after the valves - because they work by letting outside air relieve the vacuum formed by water flowing away from the closed valve. They do not relieve fluid pressure; if that were the case, water would gush out from the vents when the valve was closed (it spills when the valve is reopened, but that's just the vent's check valves closing).
In this particular scenario, the closing of the valve stops the inlet water flow (which also produces a hammer effect in the back pipe, but it's probably designed with that in mind) and the water flowing away from the valve creates a vacuum which pulls the water column back, smashing at the valve. The air vents are there to allow air to flow in and prevent this from happening.
welcome students of cardiology
Good demo
What the direction of water
North away from camera.
can u demonstrate for surge
Really good,
very cool
good job
It's impressive video for me.
How to make a Water hammer?
what she did is exactly the water hammer effect
now you just learned why its better to use screw type valves.........
So nice
cool
i still dont understand lol
Water (or gas) is moving inside the pipe. If you close the pipe quickly, the moving water has nowhere to go, so they basically press into the end of the pipe, creating a region of very high pressure. Think of it like hundreds of people running inside a narrow tunnel. Imagine what happens if you close the exit suddenly.
Then it rebounds, traveling backward in the pipe then forward again then backward, so on and so forth. Hence a water hammer, because it sounds like a series of loud bangs. This can cause serious damage (the pipe would literally burst) and is highly dangerous in certain situations.
+Angry Kittens
well said guy