My question is actually two questions in one. I believe that in my studies in school I learned that a water column is a stand of water in a pipe to a certain height. If the pipe ended at the bottom of a tank then the water column would extend up through the water in the tank to the water level but the column would still only be the diameter of the pipe below the tank. In other words if a two inch diameter pipe took the water up to the tank the water column would be two inches of water reaching all the way to the top of the water level in the tank.

The second part of the question is would it take more power to push the water up to fill the tank be greater or less than if you used the same size pipe and ran the pipe along the outside of the tank to the top of the tank, and then over into the tank. The height of the tank would be taller that the water level in the tank itself.

The amount of power or, pressure that is, would be proportional to the net height the water is pushed up. Thus to fill a tank with the pipe going up the outside and ending there, all the water would have to be raise that far. With a pipe ending at the bottom, the amount of work would increase as the height of the water did. The efficiency of the pump at different pressures would also affect the power consumed.

Would all the water in the tank affect the pressure coming out of an opening at ground level or would all the water in the tank only have an affect on the volume of water you would get at the opening at ground level. What I am tryint to determine is if all of the water in the storage tank adds pressure on the column of water or only the water that is above the diameter of the pipe in the bottom of the tank. If you know a site that I couel see this information I would appreciate it very much... and thanks for you reply to my first question.

I am not sure if this is what you are asking, but the pressure at the bottom of the column depends only on the height of the column, not the volume of water. No matter how big around the tank is, the pressure at the bottom depends only on the height.

Can't give a web site, but check any physics book.

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Originally Posted by James W. Acker

Would all the water in the tank affect the pressure coming out of an opening at ground level or would all the water in the tank only have an affect on the volume of water you would get at the opening at ground level. What I am tryint to determine is if all of the water in the storage tank adds pressure on the column of water or only the water that is above the diameter of the pipe in the bottom of the tank. If you know a site that I couel see this information I would appreciate it very much.......and thanks for you reply to my first question.

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water column ussually referring to water in column(vertical pipe); it is express in inches or feet... 1 ft WC =0.433 pound per square inch (PSI)... yes the level (hight not area)of the water will effect the pressure of the tank... as the water level is lowering... the pressure also lowering

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Originally Posted by labman

The amount of power or, pressure that is, would be proportional to the net height the water is pushed up. Thus to fill a tank with the pipe going up the outside and ending there, all the water would have to be raise that far. With a pipe ending at the bottom, the amount of work would increase as the height of the water did. The efficiency of the pump at different pressures would also affect the power consumed.

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... if the pipe is at the highest level the amount of work on the pump is the same . At the lowest level the pump do more or less work; depend on the water level in the tank( in this condition the pump/seal/connections will fail sooner) also if the discharge pipe is below the highest water level and the discharge side of the pump (water column) won't hold (leak and/or/no check valve) then there will be more problem... ussually(open water tank) they put discharge above the highest water level (except toilet tank)

The width of the water column is irrelevant. Only the height matters. Every 27.8 inches of water ( if I remember the number right) column height is one pound. If you want to work a practical problem, think about the depth of the blow out in the Gulf of Mexico. The well head is 5,000 feet below the surface of the ocean/Gulf. That means the water at that level exerts 2,158 pounds plus 14.7 pounds for atmospheric pressure at sea level for a total of 2,173 psi. That is over a ton. So now you know why it is so difficult to control the well head at that depth. The back pressure on a pump is whatever the height of the water is, not the width or volume. For every two feet of water height (depth) it takes an equivalent of one pound of pressure exerted by the pump just to be even. So the pump has to produce more than that pound in order to push the water up out of the pipe. Do the math and you can work out how much pressure you would need to pump whatever amount of water you would need to move.

texhunter - please note that this question was posed over 5 years ago! Not much point in adding to the answer now.

It is still a good question. And the people who are talking about it are not clear in their answers. Ifa question is too old for our attention, you should remove it from the listings. I am not a professor but I have skills and knowledge to help in simple technical matters.

I teach hydraulics and pneumatics. I wasn't looking for an answer to this question, but something else entirely. However, I like the example texhunter uses for a practical and contemporary example. I intend to use it this week to make my beginning students think. I also agree that it matters not when the question was first posed. What is the use of a forum like this if every question must be reposed every time someone has it. Unfortunately, the student could have used a little research so that the question would have been asked more clearly. For that reason, I think it would not be unreasonable to edit questions and answers so that future students more quickly find the answers they are looking for. Thank you texhunter.

What is the meaning of friction loss?