Air Lifting

[SteveB]

I want to lift water about 20 feet from my truck to the storage tank on the second floor of my cabin.

I used to be a commercial diver, and have used many types of "airlifts." This is a device where a suction is created by venturi-ing air into a line in the direction you want it to flow. In real underwater conditions, the air expands as it rises, increasing the suction power. It really sucks up whatever is in front of the nozzle.

I was playing with the idea of buying a pump that I could pump water from my truck tank up to the storage tank of the cabin. (This is just for winter use. In the warm months, there is a water system.) I am running into the problem that a lot of them just don't have a lot of head pressure. And they cost a lot. And they require special plumbing connectors. A small compressor would not have to put out a lot of air to lift the water in a

1/2" line and get it to rise up. The bubbles will push the water up and rise automatically.

Anyone else ever done this? Venturiing is a good way to make suction devices for all manner of applications, and they are really safe because they just use air or water.

Steve

[Bob]

You just need a pump which produces over 20 feet of head. I bet one of those drill pumps would do it slowly, although initial lubrication might be an issue. You would need to produce a pretty strong vacuum to draw water up 20 feet. I bet an RV water pump would work well. Other possibilities - used pumps - sprinkler, spa, pool, household water, etc. Or, Pressurise the truck tank with your compressor, if it can take the pressure.

Bob

[SteveB]

The air rising will lift some of the water.

Plastic barrels don't hold a lot of pressure, and the bungs leak easily.

Actually, .434#/ft. @ 39 degrees F. Salt Water, .443#

[Greg O]

Seems like the hard way to me. I think it will cost more to do as you propose than you can buy a pump for!

but it may be a tad short on lift.

How much are you willing to pay?

Here is a stainless steel one that will work.

12 volt. Greg

[John McGaw]

Somehow it just doesn't seem as though lifting water that distance should be so difficult (unless you are talking bucket on a rope). For $40.00 you can buy a simple centrifugal pump that is rated at a 23ft lift.

Spend more and you can get a bit more lift and volume but unless you are going to be doing this frequently I don't know if it would be a big thing to just spend the extra time watching it work and spend the money you saved on beer.

[gfretwell]

What was the ambient PSI when this air lift worked so well? You are a diver, think about it. The lift came from 20 feet of water pressure.

[JohnH]

[UP and Adam]

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

[Stormin Mormon]

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.

[Harry K]

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 work there.

Harry K

[Bob]

A pump that pumps to a 23 foot head probably isn't going to move much water at

20 feet.

Bob

[Joseph Meehan]

SteveB wrote: ....

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 not count)

[SteveB]

Babble, babble, babble, babble, babble ........................

Thanks for your help.

[gfretwell]

20 feet.

You have to read the whole rating. A pump is rated at "X" GPM at a given head. This pump ad says the max suction lift is 23' It will pump UP against the head a lot higher I imagine. They don't have the GPM/head curve in this ad.

[Goedjn]

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?

[Bob]

at 20 feet.

The ad says max lift with no mention of suction. The pump will pump a little water 23 feet up, and not much more. It is obviously a sump pump. Sump pumps don't generally generate much pressure.

Bob

[Bob]

at 20 feet.

A pump which generated 30 feet of head will do the job much better and more efficiently. If you are going to buy a pump, you might as well buy the right one.

Bob

[Bob]

It's actually a good (unanswered) question. If you are trying to pump into a pressure tank, you will need a stronger pump to pressurize it.

Bob

[John McGaw]

20 feet.

Even if it does move water very slowly, what is lost besides a few hours of time? A pump doesn't need to be watched for it to work so OP can be doing something else while it moves the water at its own pace. This looked like a cheap solution for a job which probably won't be done very often or need to be done quickly.

[SteveB]

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 distance.

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 pump instead.

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.

Steve