Will I die IF

[Storker]

A little off topic but what actually happens if there is an O2 fire in a tank being filled? Does the tank rupture? Does the fire burn up the O2 leaving a hypoxic mix?

I'd guess that a ruptured tank isn't very likely and that a blown valve is more likely. Most likely, you can get dangerous amounts of CO in your tank, same as if you fill from a poorly maintained compressor.

That said, I would never PP blend into a tank that wasn't O2 clean, also if I weren't going to breathe the tank myself. The risk of something going boom may be moderate, but the outcome could be rather nasty

 

[formernuke]

A little off topic but what actually happens if there is an O2 fire in a tank being filled? Does the tank rupture? Does the fire burn up the O2 leaving a hypoxic mix?

I've heard that there can be an O2 fire in a tank and you not realize it. From what I understand, the oxygen dosen't burn but rather supports the combustion of the petro chemicals in the tank. So do small oil deposits burn but without enough gas expansion to be noticed.

Just curious as to what happens.

Oxygen is not combustible but it is a catalyst and promotes burning plus makes the flame hotter and bigger. As above states the chances of there being enough combustible materials to actually cause a boom is very unlikely but you could produce nasty gasses or have a fire spread.

 

[Colliam7]

... why can't a tank that is not O2 cleaned be filled with banked nitrox? I ask only because you state that here, but I've witnessed plenty of non-O2 clean tanks filled from a 32 bank with zero problems or concerns.

As Rob said, it is done all the time. And, we don't see oxygen fires regularly occurring at scuba fill stations engaged in that practice. But, support for doing that - filling non-oxygen cleaned cylinders with premix up to 40% - is definitely declining.

For many years, the Compressed Gas Association has asserted that the threshold for oxygen cleaning is 23.5%. Most of us in the business of filling cylinders with pre-mixed / banked oxygen blends up to 40% have more or less ignored that CGA position, if for no other reason than the cost and effort of cleaning cylinders is not insubstantial, and would be expected to adversely affect the scuba industry. But, I think that is position is changing - slowly but changing nonetheless. One of the largest manufacturers of compressed gas cylinders that still serves the scuba market is Luxfer, and that company has made clear its support of the 23.5% threshold for cleaning for oxygen service (Why does Luxfer require cleaning for oxygen concentrations above 23.5%?). The CGA 23.5% threshold is also 'included by reference' in the CFR, which essentially makes it a Federal standard.

We are free to ignore it, at our own risk. But, in the (unlikely but not impossible) event of a fill station accident involving cylinder-filling with premix, the shop would certainly be at liability risk if non-oxygen clean cylinders were knowingly filled with a premix - say 30%. I am now encountering more shops that will not fill cylinders with premix unless they are cleaned for oxygen service. And, on a personal basis, I am advocating that the shops where I teach adopt that position as well.