Backyard Aquaponics
A place to discuss aquaponics

My god it is so simple... a higher powered air pump might be required but it simplifies things a great deal. Good work there njh... I can't believe we have missed something this ingenious and still rather basic.

LKB: yeah, exactly. The elbow on the end (where the water is coming out) is to ensure self priming - when there is only air in the tube the jet of induction water hits the end and fills the pipe at which point the suction starts. Here's my quick diagram (thanks inkscape). I think a long straight tail will improve efficiency. It also occurs to me that this should work in any orientation, perhaps it would be more efficient to point the tail upwards and put an elbow down to the base of the tank with a suitable foot.

Another thought - an elbow sitting on the bottom with an external nozzle could sweep the floor clean. Lots of opportunity for experimentation.

NJH,
So it's a high-pressure air-lift pump? The acceleration of the air gives extra power? Pretty cool!

I'll be testing version 2 of my geyser pump later today. Keep your fingers crossed.

No, it is a low pressure water-lift pump. The deceleration of the injected water induces a current in the tank water.

Keeping fingers crossed.

Version 2 Test Results:

After decreasing the diameter of the riser above the water line, I'm now getting consistent spurts of water to over one meter. However, the spurts are still only about 4 seconds apart, and not that much water per spurt. I was going to measure flow rate, but it was slow enough that I didn't think my husband would stand there long enough to get a gallon of water in the jug. I can't increase the volume of water per spurt since that's dependent on diameter of the riser below the water line and depth of the pump. Instead, I'm decreasing the volume of air that gets trapped under the bell so that it builds up more quickly. I still think I have more air volume than I need. Soooo....

Waiting for the glue to dry. Waiting for the glue to dry. Waiting for the glue to dry. (I think I need some plasticine modelling clay. Chewing gum didn't really do that well.)

Version 3 Test Results:

With the decrease in volume under the outer bell, I don't think I've improved things very much. I measured volume of water moved over a minute, did some math, and figure I'm moving about 10 liters of water per hour. Not impressive. Spurts are still about 4 seconds apart.

My theory is that geyser pumps work much better when you can put them at a decent depth. The only thing I can figure is to reduce the scale entirely, working with smaller diameter pipes like 'Ell started with. That way the volume under the outer bell could be better matched to the volume of water in the riser tube. Even with the reductions I've made, I think the volume under the bell is about 1.5x the volume in the riser. My suspicion is that the volume under the bell needs to be smaller than the volume in the riser.

If I get really inspired, I might re-make a smaller geyser pump. I'm not sure....designing the Tilapia Love Shack might take precedence.

njh, bernoulli's principle (you knew that )

every one working with venturii should read up on it.
http://home.earthlink.net/~mmc1919/venturi.html


Also, its been a while, but remembering back to second year process control, the maximum pressure drop will occure at some point AFTER the taper, i think there is a formula for it. So, the positioning of the vertical take up pipe should be at a point to the right (as viewed in njh's picture) for maximum pressure drop and therefore lift.


People should be able to work it out emperically by making a sliding insert taper and sliding it back and forward. One for les?
Steve

back to work for me............ snuck off a maintenance to check the forum (how bad is that!)

I dont feel so bad about sneaking away from a staff meeting to do the same anymore

i am thinking about installing a computer down near the glasshouse

Why near it, what's wrong with in it?

wireless it back to the broadband!

Or in my case, in the house, with 1-wire link.

steve, yeah it's based on bernoulli's principle. I first read about this idea in the "popular science educator" encyclopedia I had when I was young. It was a fantastic book full of beautiful illustrations of things like steam shovels, ocean liners and sugar beet factories. It also had marvelous experiments involving things like thalium and potassium chromate (neither of which you can buy any more). They don't make them like they used to.

Sorry, was rambling, ah yes, so the idea of the a venturi lift was used in prewar germany for pumping town water from dams and rivers using a smaller amount of high pressure water from small mountain dams. There was a lovely picture of a 1m diameter venturi inducer pumping water 40m using a jet of water at 400m head.

A similar design is used in steam engines to pump cold water into the boilers (called the injector). Apparently good for pumping slurries...
http://en.wikipedia.org/wiki/Injector

bear with me here, I'm a bit slow on the uptake..... the nozzle is essential right, to lower the prssure and create the lift. Any ideas on what to do if using say 40mm pvc pipe, how to makle the reucer, and how long could it be etc.

We sound simmilar! First book i remember reading was "the book of knowledge" Probably not as BIG as it seemed in my small hands.

Also, grade 6 kids shouldn't be allowed to read year 10 chem books

Last link on that page i link to is an explaination why bernoulli's priciple is ERRANOUSLY used to explain flight of planes. Not that the textbooks will ever change, but what the dude says makes sence. At least they admitted current flow is from - to +

I kid you not, when i was younger i looked at planes all the time and was shettered when i learned "how they flew" because i imagined it all wrong......HA! Vindicated

Steve ive seen the "other" therory of flight to do with the angle of the air departing the trailing edge being responsible for lift and it appears those that should know really arent decided which is more right, if you guys want an interesting one look up Coanda effect .Back to using venturi's to pump fluids(liquids and gasses) once you get to a certain point it generally isnt very efficient, I believe your maximum efficiencies are probably going to come with the geyser and airlift pumps . that doesent mean stop playing caus'e thats what its all about ,but sometimes i have to stop and ask myself "now what was i trying to do" . Now what was i going to asy ? Oh yeah, your never going to efficiently pump using the venturi but if you want to make it as efficient as possible, and this is where it gets hard cause i cant post a drawing, imagine youre pipe side on like the earlier drawing where your chaulking nozzle is pointing downstream have onother facing into it dowstream so you have a gradual taper leading in a choke point and a gradual taper leading out have your suction point on the downstream side of the choke on the taper it must be flush with the taper!

This is the most efficient design(that i know of ) instead of using chaulking nozzles you just plug the pipe with car bog(body filler) drill out to your choke point size and then carve, sand the tapers in place. funny thing was when i made one of these years ago it was for my fathers fish pond and it was using water to create a venturi to suck air into the water stream to areate the water, here were looking at the reverse.
By the way the whole things very sensitive to changes in dimension ,taper length choke size position of and size venturi pipe etc etc etc to the point where it just wont work some times.