Making an air LIFT
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  1. #1
    us
    Oct 2005
    New Jersey
    JW Fishers
    81
    2 times

    Making an air LIFT

    Sorry, ref. the last post, I meant an air lift. Would appreciate any info and input. Thanks.

  2. #2

    Oct 2004
    290
    1 times

    Re: Making an air LIFT

    Here are some pic of a 2-inch I built. It was 20-feet long.

    Dinkydick
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  3. #3
    Seahunter

    Jan 2006
    PALM BEACH COUNTY,FLORIDA
    820
    35 times
    All Types Of Treasure Hunting
    Banner Finds (1)

    Re: Making an air LIFT

    Dinky
    What size compressor did you use and in what depth?
    Seahunter

  4. #4

    Feb 2007
    South Berwick, Maine
    166
    33 times

    Re: Making an air LIFT

    Hey Dinky...

    The 20 ft length and the curved exhaust I assume, was to raise the debris to the surface? Possibly to screen the sandy debris for coins? Relics?

    How well did the 2" pipe work as compared to 3" and 4"? How deep were you working this?

    Thanks for helping,

    Wayne

  5. #5

    Oct 2004
    290
    1 times

    Re: Making an air LIFT

    The airlift I constructed was for taking bottom samples for radioactive
    sediment. It was built small because of the boat I was using. I ran it off
    a SCUBA bottle (80 cuft) which lasted about 5 to 7 minutes. It did the job.
    I used SCH40 pipe as this is what I had on hand. SDR or thin wall pipe will
    work just as good and will be lighter to carry. The airlift was not glued
    together because of space limitations. The loops of wire ties held the airlift
    together when it was put in service. A smooth curving exhaust is a must.
    Do not use a sharp 90-degree elbow as it will affect operation of the airlift
    and put additional loading on the suction end and slow down the lift. If you can
    keep the exhaust end at the surface or below the airlift will work best. An overall
    length of the airlift pipe of 10-feet is sufficient for the lift to work. You MUST
    keep the pipe vertical in the water for it to work. The compressor requirements
    are the only thing which needs to be somewhat right. Airlifts work on air
    volume and not on air pressure. In 20 to 30-feet of water a 45psi air source
    will work but you need atleast 15 to 20 cfm. This is the problem. Compressors
    with large volumes are LARGE. I leave this up to you for a compressor solution.
    Most of my airlifts were ran off of rotary screw compressors which have volumes
    of 125 cfm and above so I always had plenty of volume. Larger pipes require
    larger volumes.

    Hope this helps.

    Dinkydick

  6. #6
    us
    Oct 2005
    New Jersey
    JW Fishers
    81
    2 times

    Re: Making an air LIFT

    I was thinking about a 4 to 6" diameter pipe and will be working in about 18 to 25' of water. I'm wondering what a reasonable compressor would be? What would my minimum CFM be? If I get too large then I'm defeating the purpose of utilizing a lift on a small boat. Anyone know where I can find guidelines regarding CFM to depth ratios? Schematics and/or plans would also help.

  7. #7

    Nov 2006
    152

    Re: Making an air LIFT

    We constructed a 4" flexible pipe (spiral re-inforced) for use in 50-60 ft water on the Margarita site for emerald recovery....it worked really well, but we had a HUGE Ingersoll-Rand compressor,
    like the kind yousee on the side of the road on wheels being used with jack-hammers to break concrete. I'm sorry, I can't find the CFM in my notes right now, but it was (I think) around 150.
    Man, that thing would give you a RIDE if you turned the valve controlling it before youhad it buried in the sand bottom!! We had to stop sucking every 5-10 minutes because its output (sand, rocks, shells....and sometimes emeralds...) would bury the aft deck of our workboat, and overwhelm the sorting screens. ( Which varied from bread racks size to chicken wire and then to smaller actual screen) Good luck with your endeavor! Mike

  8. #8

    Oct 2006
    Coastal, NC
    Garrett Infinium LS, Garret Seahunter MK II, Geometrics 882, Marine Sonic SS
    1,326
    2 times
    All Types Of Treasure Hunting

    Re: Making an air LIFT

    The best place for you to start if you plan on working from a small boat and getting any effective work done is figure out exactly how many CFM you've got to start with and work it backwards. unless you've got a big boat that can support a large diesel rotary screw compressor like Skimmer is talking about i.e. 185 CFM your not going to be able get much done with it, or pile of scuba tanks and a good back. Unfortunately there is not much of a cost effective happy medium in self powered portable compressors. Your best bet as already suggested might be using an induction dredge such as Keene makes.
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    www.coastalmarinesalvage.com

  9. #9
    us
    Jan 2005
    Ocala florida
    Titan / Tesoro SLT/ Fisher F5
    137
    1 times

    Re: Making an air LIFT

    I am going to toss this out there, the last time this was discussed I had just returned from a weekend at Seahunters and an idea popped into my head. For a shallow application (like at seahunters). A commerical ( gas powered ) back pack blower ( what a lawn service would use ) mounted up in a little frame. As posted the volume is more important then the pressure, and a reduction in diameter down at the turn will add a bit of volicity / pressure. This should be a pretty easy to do experiment to see what it might or might not do. Some of these units have some pretty big outputs.

  10. #10

    May 2006
    1,520
    2 times

    Re: Making an air LIFT

    THIS IS VERY VERY INTERESTING.
    I have a gas powered weed blower that I use to provide the volume of air form a blast furnance that I used to use. The end opening was about 2.5 inches in dia. It was able to put out a 110 mph wind. It had a second setting that was able to put out about 40 mph wind.
    I guess this means nothing untill I can figure the volume of air. My wife is looking for device right now.
    THIS is a GREAT IDEA.
    THANKS
    Peg Leg

  11. #11

    Oct 2006
    Coastal, NC
    Garrett Infinium LS, Garret Seahunter MK II, Geometrics 882, Marine Sonic SS
    1,326
    2 times
    All Types Of Treasure Hunting

    Re: Making an air LIFT

    Not enough pressure, you need at least 20 to 30 psi or more at depth for an airlift to function, then an additional 1/2 psi per foot of depth. Also remember that volume is a function of pressure.

    Take your leaf blower and taper down the output and try to inflate your car tire, it ain't gonna happen captain.

    www.coastalmarinesalvage.com

  12. #12
    us
    Pirate of the Martires

    Feb 2005
    Port Richey, Florida
    Aquapulse, J.W. Fisher Proton 3, Pulse Star II, Detector Pro Headhunter, AK-47
    3,654
    1983 times
    Shipwrecks

    Re: Making an air LIFT

    I made this 2" airlift to work off my power inflator hose. No hose to the surface required. It works pretty good. Instead of one hole going in the side, the band has about 50 small holes going all the way around. This reduces the bubble size and makes more small bubbles. The result is a 2" dredge acts more like a 3" dredge.
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  13. #13
    us
    Jan 2005
    Ocala florida
    Titan / Tesoro SLT/ Fisher F5
    137
    1 times

    Re: Making an air LIFT

    Brad, Look at Echo PB650 - 63.3 cc engine. Not on a good monitor so the numbers are to fuzzy to read, but the small one ( 44 cc ) looks like 10.3 cubic meters / min. the 63 cc is larger but I can't make it out. Scott is working 10 to 12 feet of water so that would add 5 to 6 psi, not arguing with you cuse I don't have knowledge to do that, just pointing out I meant commercial not general home owner units.

  14. #14
    us
    Pirate of the Martires

    Feb 2005
    Port Richey, Florida
    Aquapulse, J.W. Fisher Proton 3, Pulse Star II, Detector Pro Headhunter, AK-47
    3,654
    1983 times
    Shipwrecks

    Re: Making an air LIFT

    Hey Skimmer, I built a 6" airlift in Key West to dredge for emeralds on the Atocha site. It used the same principle, a stainless steel band around the tube with 150 holes around. The compressor we used was a 110cfm unit. Heres a picture of the dredge on top of our 100' salvage boat. Notice the compressor in back. I didn't know anyone dredged for emeralds on the Margarita site. Find any?
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  15. #15

    Oct 2006
    Coastal, NC
    Garrett Infinium LS, Garret Seahunter MK II, Geometrics 882, Marine Sonic SS
    1,326
    2 times
    All Types Of Treasure Hunting

    Re: Making an air LIFT

    No, I didn't take it the wrong way. At 10 Cubic meters per min that equates to about 350 CFM.

    Boyles Law say PV=PV
    1psi x 350cfm = 35psi x V
    V=10 cfm assuming perfect efficiency

    I just don't think that a leaf blower is built to tight enough specs to develop the kind of pressure and volume required. It would be very simple to find out; just cap off the output and put a pressure gauge on it. Or taper down your output to a reasonable sized hose and take it underwater and see how deep you can go and still deliver air.
    www.coastalmarinesalvage.com

 

 
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