2" airlift in 90 ft of water, psi and Cubic ft/ min?

[DBrick81]

How many cubic feet/min at what psi would you need to operate a 2" air lift in 90ft of water? Also would the discharge have to empty into a basket just below the surface or could you run the discharge 3 or 4ft out of the water onto the deck of a boat.

Thanks,

Dave

[ScubaDude]

10 to 15 CFM at 20 to 30 psi above ambient.

So at 90 ft 65 to 75 psi at the surface should do it.

From that depth you can run it out of the water and onto the deck.

You really ought to consider a larger lift, 3 or 4 inch minimum. If you do go that route you'll need more air.
30 ish CFM for the 3"
50 ish CFM for a 4"

They will function with less but not as efficiently. At that depth you need to figure out a way to anchor the bottom end, if it gets clogged up the entire apparatus will depart for the surface rather quickly, make sure you and your boat are not in it's path.

[Dinkydick]

What are you trying to recover?

A 2-inch airlift that is 90-feet long? How are you going to
manage this monster?

Give me a little more information and maybe I can help you
out.

I have built many and operated hundreds in my 54 year diving
career.

Dinkydick

[ScubaDude]

We had one nice one built from an 8" aluminum tube. It got clogged and the suction was so great that it ended up collapsing the entire length of tube. The moral of the story is keep your hands (or anything else you don't wish to lose) away from it at all times. It's replacement was a piece of 8" polybutylene pipe. You can also bolt or strap diver's weights to the end of it to help balance things out when it is operating, otherwise it will try and pull you toward the surface.

[DBrick81]

I would love to build a larger air lift but I'm kind of limited to the space on my friends 28' boat, and how big of a compressor I can afford. Also I don't have one job in particular for the airlift, me, my dad, and my friend are just looking to do some small scale treasure hunting on wrecks in the area. Actually, I have one more question. At about what depth would I no longer be able to run the dump end of the lift over the 3' side of the boat?

[Dinkydick]

I hope your boat has good bilge pumps as you will need them if you
plan on bringing the open top end anywhere near the boat. The water
and dredging will be flying 10 to 15 feet into the sky. I hope you realize
this.

Question - Why do you want to build an airlift which discharges into the
boat on the surface? You can run a short airlift under the water just as well.

FWIW information - Every inch you extend the discharge end of the airlift
out of the water the less efficient it becomes.

Dinkydick

[DBrick81]

Would a 23-26cfm at 100psi compressor work for a 3" airlift at 90 feet? I should say would it work well enough because I know its a little low on cfm. But I can find a few compressors in this range for fairly cheap.

Thanks,

Dave

[ScubaDude]

It's not ideal, but it will work.

[wreckvalle]

How many cubic feet/min at what psi would you need to operate a 2" air lift in 90ft of water? Also would the discharge have to empty into a basket just below the surface or could you run the discharge 3 or 4ft out of the water onto the deck of a boat.

Thanks,

Dave

Dave,
Maybe you should try a water dredge. We use a 3" water pump and can dig down to 150' with no problem at all. What make the water dredge neat is that the same unit can be used in 5' of water and no surface disturbance is created. All sand is blow out about 5-8' downcurrent.

check out
http://www.shipwreckexpo.com/shipwre...excavation.htm

Good luck
Capt. Dan
www.aquaexplorers.com
www.thewaterfrontexpo.com

[cpt scuba]

28 ft boat not going to have the rrom for the compressor what you should do is is it about 12 ft long 1 diver runs the front end 2 nd diver works the fall out with md as objects of diff weight will settle out in diff piles you want miss any thing even if it not metal [ like emeralds ] and you wont have all that sand and silt to deal with on surface