How Do You Inflate A Liftbag?

[scubasavvy]

Ok, I'm a total noob and googled this answer the other night, but I couldn't find anything. How do you inflate a lift bag? Do they hook up to your air supply via the low pressure inflater hose or do they have their own pony bottle? Sorry for the idiotic question, it's just something I'd like to know about...

[finflippers]

Mine is open on the bottom i just inflate it with my octo.

[thor]

The bags I have used you inflate manually by putting air from your octo, or other air sorce into the bag, using the purge button, a little at a time, to prevent a runaway lift bag. Some even have a purge valve on the side to adjust buoyancy

[scubasavvy]

Are they all pretty much open at the bottom or are there multiple types?

[finflippers]

There is a pillow bag type but I have never used one of them they are not open on the bottom.

[ScubaToys Larry]

A lot depends on the bag - the size, and how much air you need in it. The most common method is just use the octo. Be careful you don't put in too much at a time, and watch your air supply before, during and after.

And be careful you keep your hoses clear of the bag so if you goof up and it starts to go up, it does not take you with it.

Also, you put in enough to make it neutral - not positive... then as you slowly ascend, you bleed off the air with the dump valve. Be very careful it does not get into a run away ascent as the air expands, then it can hit the surface, dump the air, and the anchor, brick, what have you - comes crashing down on you. So it you lose control and it gets away - swim sideways fast.

And you would want to do some calculations on how much air would it take. If you want to get into the math part - check out this: http://scubatoys.com/education/archimedes.asp

[scubasavvy]

So you work it just like your BC? The buoyancy thing is similar, correct?

[mike_s]

Originally Posted by scubasavvy

Are they all pretty much open at the bottom or are there multiple types?

you pretty much have 3 types of lift bags.

1.) open on bottom (completely open)
2.) open on bottom, but with a diaphram valve to keep air in on surface (so semi-closed)
3.) Closed, completely, air gets put in via a LP inflator connector or other.

Most all bags have a dump valve which also might act as an overpressure valve.

Be carefull of using bags that are completely open on the bottom. If they hit the surface and roll over, they can vent the air which will sent your lifted item back to the bottom and could land on another diver.

Never hook/clip an inflated lift bag to your BC either. FYI.

[finflippers]

if you are using it to carry something correct. you keep it neutral and not let it get above you. I use mine when I am at 15' for a mid water safety stop by sending it to the surface and hanging on it.

[scubasavvy]

Ok, I understand now. Finflippers, I like your idea about using it for your safety stop. Thanks so much for your help, guys!