Best way to empty air from your tank...

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BlueDolphin

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Other than the obvious (GO DIVE!)...

What is the best way to release all the air from a tank?

Is it best to just open the valve up wide open....? Or bleed the air slowly? What about condesation and freeze effect? If you let the air out quickly will the condensation form on the inside, as well as the outside? If moisture does get inside the tank... how should one get it out?

Just some questions I had.... as I need to work on some of my tanks and need to remove the manifold/valves.
 

Uncle Pug

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...what is best... but I bleed them out slowly.

As for drying tanks out inside... I have an old bonnet style hair dryer that I confiscated and use the hose for drying gear out... for tanks I stuff a length of 1/2" tubing into the dryer hose and then stick the tubing down into the tank.
 

Iguana Don

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Turn em upside down and dump it out!
 
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Iguana Don once bubbled...
Turn em upside down and dump it out!

I usually wring 'em out afterwards......

(Slowly... and for extended storage - leave about 200-300 PSI inside to stop moisture from getting in.)
 

Groundhog246

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Ontario Diver once bubbled...


I usually wring 'em out afterwards......
(Slowly... and for extended storage - leave about 200-300 PSI inside to stop moisture from getting in.)

Ontario Diver, how do you get the pressure to stay up, when you remove the valve? :D

My understanding from LDS, is as let air out as slowly as possible. That'll reduce condensation to as low as possible. I was haning around last time they opened up one of mine and after at least 20 minutes lewtting the pressure drop, not even a trace of moisture inside the tank.

For anyone who's never looked at a valve off the tank, there's a tube projecting about 3" into the tank, so you could have 2"+ of water in the tank with it inverted, and it's not coming out through the valve (and thus, not into your first stage).

Kent
 

pescador775

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Blue dolphin, as others have said, let the air out slowly, about 1-2 hours to dump a full '80'. Even so, there may be condensation. If it's a humid day, let the tank stabilize at atmospheric temp before removing the valve. Otherwise, warm, moist air may enter and condense on the cold inner wall. If moisture is found in the tank, use the hair dryer trick. Use a dryer that is not more than 10 years old as the really old ones used asbestos insulation which could flake off into the air stream. Blow air through the valve before installing.
 

SDAnderson

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Although it's a good idea to go slowly, taking an hour or more to drain an AL80 in your garage would seem to be silly. Most of us have come close to emptying one in 20 minutes at depth and that doesn't seem to create problems...

Steven
 

Newhampster

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Most of us have come close to emptying one in 20 minutes at depth and that doesn't seem to create problems...

The water is a great thermal conductor.
Above the water, the atmosphere is not as good a conductor.

Besides, you don't drain your tank to 0 psi underwater and you don't remove the valve, either.

So the two emptying-scenarios aren't comparable.
 
OP
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BlueDolphin

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Better take off the valves and dry them out. They did appear to get condensation on the outside.
 
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