Safety Pressure

[Braunbehrens]

pescador775 once bubbled...


That's your perogative. May I ask, just what is the minimum pressure that will keep water out of a tank? I ask because you say 5 psi is not enough.

It is quite possible to flood a tank yet still have positive pressure on the surface. Think about it!

OK, for those of you who prefer to have your thinking done for you....

Let's say you get the tank to ambient at 100 fsw. Then you descend to 120, and some water gets in. Then you go to the surface. The tank now has about 45 psi in it. (100 fsw = 4 ata or so, surface is 1 ATA, the difference is 3 ata or about 45 psi).

I have done this with an argon bottle. Would be hard to do with the one you're breathing though

 

[MikeFerrara]

pescador775 once bubbled...


That's your perogative.

Yes it is. At 5 psi there will be no hiss and it won't even show on a HP gage. The tank will appear empty and I won't fill it.

 

[pescador775]

Braun, you are answering a question that was not asked. It's also a cheap shot. If pressed, I can construct a confounding, mind twisting answer to any question YOU ask. All I have to do is fool with the premises.

 

[Braunbehrens]

pescador775 once bubbled...
Braun, you are answering a question that was not asked. It's also a cheap shot. If pressed, I can construct a confounding, mind twisting answer to any question YOU ask. All I have to do is fool with the premises.

How do you figure? You asked what is the minimum pressure to keep water out of a tank? My answer is that it's a different pressure depending on where you check it. Any positive pressure will keep water out, but positive pressure during the dive basically means you have at least 30 psi in your tank on the surface.

If you know the shop, as I do mine, you can get away with things. For example, I once emptied a tank on the surface, and I simply told them this and they know me and believe me.

Also, if you know the shop, the guy will probably do a quick look see in the tank just to be sure, and not charge you. There certainly is no harm in that.

 

[MikeFerrara]

Of course...if you have an idea how and where the tank became empty a little common sense can be applied. Once the tank is empty it only takes a secon to take a peak inside to check for water anyway.