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Thread: DIY Airlift?

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    LAR Addict RGMag is a jewel in the rough RGMag is a jewel in the rough RGMag is a jewel in the rough RGMag is a jewel in the rough RGMag is a jewel in the rough RGMag is a jewel in the rough RGMag is a jewel in the rough RGMag's Avatar
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    DIY Airlift?

    Hi folks, has anyone here ever build or used any type of Airlift to remove sand and sediment from the seabed? Is there a problem with the system in shallow depths, for example around 1-2m water depth, would the suction be enough to remove sand on a 5mx5m area?

    At the moment Iīm thinking of 5m 50" spiral hose with around 50cm 50mm PVC pipe attached as a nozzle and handle. Problem is the air delivery, I want to use a 80cuf stage to supply the thing with air, in some spotīs I read you need only short bursts of air, so fit an inflator type button and press it every 5 secīs (as long as the bubble travels the hose/pipe) but other places write that a constant and finely dispersed air stream is the way to go? So what do you guyīs think?

    The inflator button style would give quite good control about air consumption I think?

    Has anyone experience in how air hungry these tools are? One website stated that a 50mm hose one consumes about 1000psi in 10minīs, that would be ok for me if it can remove a lot of sand in this time...

    So, any tips or hintīs?

  2. #2
    Longbottom Time RAL is a glorious beacon of light RAL is a glorious beacon of light RAL is a glorious beacon of light RAL is a glorious beacon of light RAL is a glorious beacon of light RAL is a glorious beacon of light RAL is a glorious beacon of light RAL is a glorious beacon of light RAL is a glorious beacon of light RAL is a glorious beacon of light RAL is a glorious beacon of light RAL's Avatar
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    Re: DIY Airlift?

    The three things to remember with an air lift are volume, head and more volume. The closer you are to the surface the greater the head difference for a given depth so shallower is better to a point.....but with just 1 meter you are limited to about 1/10 an ATM difference.
    At the 2 meter depths your little lift will work better as you can use a 2 meter pipe and that with give you more head differential = greater lift. You could make something that would work... sorta but you have problems. 80cf is not going to let you work long, you need volume to make these things work. No sperts are not the answer, did I mention you need volume. Also you are only using a 20" length tube, 20" will be good for nothing more than an exercise in frustration. It will develop very little lift, if any, even if you had enough air volume and somehow got it so suck rather than blow half the air out the bottom of the tube the spoil will just drop right back in your hole. Working in 2 meters with a 2 meter long air lift it will work but your 80 cf supply will only give you a very short working time, plus much of the spoil will still rain back into your hole unless you have current. A few years back I made a lift and supplied it with overpumped twins, about 280cf per set. Used a section of 2" pvc pipe about 8' in length plus a section of 2.5" flexible hose on the end due to the logistics. The work was being done at @20'. the discharge end was @5' and well away from the work site. It worked seasonably well...but...we only excavated about 8" deep in an area of sand about 8'x3'. We had 8 sets of twins pumped up. One set would last about 5 to 8 minutes as I recall. Topside one man changed out tanks as they ran dry while the other man worked the lift. Why didn't we just use a lp compressor? Stealth but thats another story The point is these things can be done but there are better options unless there are some factors that negate them.
    Why are you limiting yourself to this very abbreviated set up....logistics working out of a kayak?? What are doing...looking for gold coins.
    Working that shallow with limited resources using a scooter to blow away the sand may be a better option. I really cannot say as I am guessing on what the project is.

    RAL

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    RBW Member Jon Nellis will become famous soon enough Jon Nellis will become famous soon enough Jon Nellis will become famous soon enough Jon Nellis's Avatar
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    Re: DIY Airlift?

    Don't even consider an airlift for shallow operations, it will be a waste of time and materials. Look at venturi pumps like those used for gold dredging. Keene engineering makes good suction nozzles and jet pumps, sometimes you can find them used or it is not too difficult to build your own. Then just rent a water pump that puts out decent pressure, the more pressure the better. With one of those, you can send the spoils further away from the sight, or to the surface to be filtered if you are looking for something small. If you are trying to be super stealthy about it, that can get more expensive and involves modifications to a high power scooter.


    Cheers,
    Jon

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    RBW Member venturi is an unknown quantity at this point venturi's Avatar
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    Hmm. Get a scooter and let it blow.

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