What is the danger?

[Coll]

Hi all, up to date, I've been renting my tanks to dive and so I don't know too much about tank maintenance. I have to go to work tomorrow however, and dive a pool to do some repair stuff, my work facility has some scuba gear but it hasn't been serviced in at least three years so I'm bringing all my own stuff except for a tank. Their tank has about 1100 psi in it and as far as I know it hasn't been tested (visual or hydro) in possibly up to a decade. My question is, what are the dangers of diving an unused tank?

 

[FireDiver443]

If it's a steel cylinder, it's possible corrosion (rust) could have occurred, which can flake off and become lodged in the tank valve or your regulator, limiting air flow. Additionally, it's possible that during the process of oxidation of the steel, the oxygen concentration is reduced from the 20.9% we're accustomed to breathing. This could cause you to lose consciousness under water.

If it's an aluminum cylinder, instead of rust you need to be concerned with aluminum oxide dust which may have formed as a result of internal corrosion, which ALSO could lodge in your tank valve or regulator.

It's your call, but I'd be inclined to rent a tank that's in hydro and viz and use this other one as a door stop as you bring in your equipment.

 

[fisheater]

Good advise. Besides, tank rentals are cheap! Especially if your boss pays for it.

Oh. If your boss insists on your using the ancient tank, just mention OSHA and all of the requirements for commercial diving. I doubt that he'd want to have a recompression chamber on site for you, for instance.

 

[Codyjp]

or, you could save the cost of a few beers and risk your life! I also believe that the oxidation and rust will lower the O2 levels in the tank. You could just offer to take it off your bosses hands and get it serviced. then you would have a nice tank!

 

[spectrum]

Yea, bring or rent your own cylinder.

I would offer to get the old one current (at their expense) just to keep you and others out of future peril.

In addition to low oxygen and gear contamination none of the potential contaminants will do your lungs any good.

Pete

 

[divinginn]

all good advice,it not worth taking a chance even if it is a pool.

 

[nereas]

I would not breathe from a tank containing an unknown gas.

If it contains argon or carbon monoxide then it would kill you.

If the oxygen is less than 15% then you will likely lose consciousness and that would kill you underwater.

It is a lot easier to drain the tank, open the valve, inspect it for rust or other contamination, then close it and refill it with air, than to do anything else with it.

Tanks should be vis-ed in this manner every year to check for rust (steel) or other contamination or thread cracking (alum) anyway.

And you should never breathe from a tank of unknown contents. Doing so would be just plain reckless. This is the danger, to answer your original question.

______________________

reck·less –adjective 1.utterly unconcerned about the consequences of some action; without caution; careless (usually fol. by of): to be reckless of danger. 2.characterized by or proceeding from such carelessness: reckless extravagance.
[Origin: bef. 900; ME rekles, OE recceléas careless (c. G ruchlos)]

 

[Codyjp]

and if we don't hear from the OP we will be left to guess his fate!

 

[wedivebc]

Of course one could analyze the gas. Has anyone tried testing the O2 in an old unused tank? I suspect by the time the tank got corroded enough to reduce O2 to hypoxic levels it would have burst due to metal fatigue. More than likely the air would be fine but I agree with the others. Why take a chance.

 

[nereas]

and if we don't hear from the OP we will be left to guess his fate!

Exactly!