I may wish I did not respond to this but here goes. If you are talking
like a hydralift where the air is injected into the pipe at the base
then you would need around 10lbs to lift 20', however the 10lbs will
be pushing back into the tank also.
If you have a strong tank at the base and put 10lbs on it with the
outlet at the bottom it will push the water out first.
Think I'm right at 1/2lb per ft.
My $0.02 John
I think that you'll have better service if you use some kind of a
centrifigul or rotary vane pump that's designed for pumping water.
Think in terms of RV fresh water pumps, or perhaps bilge pumps. Keep the
pump as low as possible. It's a lot easier to push water than to pull it.
Perhaps even keep the pump lower than the truck tank.
I see no one else mentioned it. There is such a thing as 'bubble'
lifting. Basically small diameter tubing with air inserted in the
bottom, It doesn't work by 'suction' but by the natural force of a
bubble rising in water. Each bubble pushes a slug of water up teh tube
as it rises. That should work but it would be a slow proposition.
There was quite a discussion of that plus other options over on
alt.energy.homepower recently but I don't recall the thread title.
Involved moving water 200 ft uphill. they seemed to think it would
I doubt if you are going to make it to the top. I suggest a real water
pump. Using air to pump from the bottom to the surface of water works, but
it does not work well above the surface of the water (a second surface does
It's not clear what kind of pump you're envisioning, a venturi pump,
or a bubble-lift, because you start talking about one, and then
end up babbling about the other. but neither one is going to
work for your intended application anyway.
Is this overhead tank pressurized?
I'll wager a days pay against a donut hole that it will work. If you put
some air pressure on there, it will blow the water out the other end a good
In everything engineering, I take things to the nth degree. Imagine what it
would be like if you put just enough air in the line to percolate small
bubbles up the column of water. Now imagine 150psi of air.
Do you think that will move some water?
As I said, a days pay against a donut hole. I get $85 per hour, so that's
$680 betting that it will work.
The downside is that one poster stated that the quality of air will
contaminate the water with oil, and he is correct. So, I have opted for a
But yes, the idea will work, and it would work for a very long distance if
the venturi is configured to pull the water into the airstream.
In the original post, I mentioned "venturiing". Any compressor will move a
lot of air if it isn't being compressed, and any old compressor can shoot
enough air into a venturi, and then have it rise through a column of water
to work. Remember, the top of the column of water will be open, so there
will only be the resistance of the water. The trick, to me, would be to
keep the diameter of the hose small enough so that the bubbles make a 360
degree contact with the walls of the tube.
One day when I have nothing to do, I shall set this up and let you know how
well it works.
How do you plan on filling the water-column in the first place?
And why don't you just use THAT method to fill the tank?
And if you're depending on the venturi-effect to get the
water into the lift-column, how do you expect to get ENOUGH
water in there to seal in the next bubble? All you're
going to get is an atomized spray. That will, admittedly,
get a nominal amount of water to the top of the exhaust
port, just not enough to matter.
Well, dude, it looks like you have it all figured out. Thanks a lot for
saving me a lot of time. But then, I do have a lot of time, and an
unsatisfied curiosity, so, I think I will just play around with it some
IF that's okay with you, that is.
"Whether you think you can do it or not, you're right."
I haven't used the word. A venturi operates on the principle of a
reduced section of pipe (in this proposed system) with an air injection
(or water) mounted so the nozzle is in, or just before, the reduced
section. A jet pump works on the same priciple, pump a bunch of water
up the pipe to draw more water into the stream. I actually built a
"mud" siphon of plumbing parts to clear siltation from a smal
irrigation pond, used water for the moving from the irrigation pump for
the motive source.
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