Bleed old air from tank?

[Angry Turtle]

On an empty tank? Sure, on a tank with more than 140psi? Not possible.

Agreed, it says that they used an empty tank. People with common sense and who follow their training do not breath tanks dry, and then press the purge 10 times.

 

[Superlyte27]

So... I'm going to go back to my original statement, but with some additional qualifiers...

If you count on your original training....
You can store a steel tank filled with Nitrox (that's any mixture of Oxygen and Nitrogen) for up to a year without issue...

If...
You didn't get a wet fill full of saltwater (which I simply can't think of a reason this would be possible unless your compressor is underwater )

And/or...
If you breathed your tank dry underwater in saltwater, then purged your 2nd stage repeatedly then you didn't get it inspected before you refilled the tank.

 

[GrumpyOldGuy]

It would be interesting to have someone with some chemistry background calculate the possible reduction of oxygen with a realistic water exposure and storage for 1 year. Once we know if it is possible, then we can determine if it is likely.

I know it can be done, but I don't trust my calculations.