Scuba tank air dredge?

[SADS 669]

Do any of you clever chaps or chapess?s have any design ideas for a scuba tank air dredge.

I have 12 scuba tanks that I want to use as an air dredge supply, obviously one at a time, a bit like taking a scooter to the seabed.

A bottle of your favourite rum, whisky or soda for a design we use?. Ha ha

 

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[ARC]

Well over a decade ago I built a simple air lift using the second supply line from my comp using clear large Acrylic tube first... then later designed one from extra thick torched boro glass.

The idea was to see material lift etc.

 

[SADS 669]

Got one person available to work each end and the sand will fall through a basket, any ideas about how to use the scuba air to move the sand?

 

[agflit]

Kevin-

Best I can suggest is KIS principle...

3" PVC sch 40 pipe....with 2" nozzle....1/2" fitting at lower end near nozzle to pipe air in...with a ball valve for air cutoff.....a set of doubles should drive it for maybe 10 minutes at 30'. And it will NOT be very strong.... I have a few other idea's, but...

And remember that alot of air is gonna create alot of surface disturbance.

 

[Boatlode]

Kevin-

Best I can suggest is KIS principle...

3" PVC sch 40 pipe....with 2" nozzle....1/2" fitting at lower end near nozzle to pipe air in...with a ball valve for air cutoff.....a set of doubles should drive it for maybe 10 minutes at 30'. And it will NOT be very strong....

I didn't have the numbers, but I expected this.

Kev, why not buy a small compressor and float it on a raft? Like a hookah sized compressor maybe.

 

[ropesfish]

Some resources: https://www.researchgate.net/public...ation_in_sedimentological_underwater_research

http://www.treasurenet.com/forums/d...9-2-airlift-90-ft-water-psi-cubic-ft-min.html

 

[FISHEYE]

Why use air,use water.its alot easier to pump water down to the bottom for a suction dredge than air.you could park the water pump on shore or in a boat

 

[Tommybuckets]

I've toyed with this idea a lot. How about a cylinder full of water that you blow out using air. You'd probably want the traditional venturi setup on the bottom end. It'd obviously need to be refilled with water each time. I always wanted to try n engineer one with a high volume toilet plunger but KIS is crucial to things actually working lol. I think it'd be fun and pretty cheap to do the plunger idea but shells and things may just keep it clogged lol. I wish I could attach some sketches.

 

[xaos]

The issue with an air dredge is that you bring up water, and air...air in water makes it lose the lift capability...a very careful balance, and really only small scale, very fine sands even have a chance...

That table shows 20 to 40CFM?

They used 3 tanks in 30 minutes.....seems like you spend more time with tanks than its worth

an submersible dredge is a good possibility...rather than pump to the surface, the dredge is near the bottom...small distance to pump....

are you looking for recover or to move overburden?

View attachment 1089530

You could use the compressed air to run an underwater water pump to power the dredge...

rig up a compressed air drill to power a keene dredge waterpump...no reason it all cannot be underwater!

 

[SADS 669]

Ii understand and agree with all of the comments about moving water and pumps etc but the question was about scuba tanks because I have just been given a dozen tanks that I dont need for diving and was soliciting opinion purely on the ? taking tanks to the bottom?? question?

I think based on what has been said and an opinion via phone from Agflit that using them with a cut off hose instead of fanning would be their only sensible use underwater.

 

[xaos]

power airtools underwater!
That being said, I did use an air powered drill with an auger but with my 4" dredge ...

made working the gravel and hardpack really easy...