burn marks inside alu tank

[dinogep]

One of my friends filled a brand new, hitherto unused alu tank with O2 (he assumed, that since it is brand new, oxy cleaning is not really necessary before the filling), and afterwards the O2 smelled really bad (a bit like chlorine). We suspected the tank valve seat, but after dismounting the tank the seat looked intact. On the inside of the tank however there were black patches (soot?), so we now think that the smell was caused was some contamination on the inside of the tank wall. Is it possible that something during the manufacture contaminated it (so his assumption about the cleanness of the new tank was wrong), or should we suspect that it was not as brand new and unused as stated by the seller?

 

[Doppler]

I too would suspect the seat or another component in the filling/delivery system. This is a far better candidate than something inside the tank. However, a mystery is a mystery. Certainly a common practice is to visually inspect the inside (and outside) of ANY and all tanks purchased new or second-hand

 

[Scared Silly]

I would not assume that just because a cylinder is new/unused that it is O2 clean. Not in the least. So yes, that was the first mistake. As to what happened, no clue.

 

[dinogep]

I think the filling system can also be ruled out, on the basis that several tanks were filled that morning and this was the only one with the bad smell.

 

[captain]

I think you should thank your maker that you are able to write this post then get up to speed on oxygen handling.

 

[Skooter]

I think you should thank your maker that you are able to write this post then get up to speed on oxygen handling.

That's good advice. Even new tanks will require cleaning before being used with 100% oxygen. Be thankful that you are able to post and learn what to do next time.

Found this as food for thought.

http://www.youtube.com/watch?v=9lw_fhNAIQc

 

[dinogep]

I don't see why should I thank anyone: I was at least 40 kilometers from the scene Nevertheless I was asked whether the stuff that burned on the tank walls could have come from manufacture (I'm a chemical engineer, and sometimes other divers think I can tell everything just by looking at a soot stain). I don't know enough about the manufacturing of tanks to answer that, but I'm curious enough to ask it here. If you could answer the original question, I would be happy to pass your comments to the guy who did the filling.

 

[Wookie]

My guess is the stuff that looks like soot is really the form release agent. Luxfer talks about it in their aluminum cylinder video. I bought a bunch of Worthington/HyMarks when they were still HyMark and they were all black inside. No amount of washing or cleaning would remove the marks, and I rejected them for O2 service for exactly the reasons you state. They are O2 cleanable, but if you can't really inspect the shiny silver walls, you won't really know, will you.

I have burned my share of teflon seats in O2 cylinders, especially on Sherwood valves. Never burned a seat on a Thermo. The smell is horrible, but there is no soot/charring of the cylinder wall. If I suspected it was soot, I'd look in the dip tube first. What kind of cylinder was it?

 

[Doc Harry]

...he assumed, that since it is brand new, oxy cleaning is not really necessary before the filling...

I wonder why he make such assumptions?

I think most people would make the opposite assumption - that a new tank from the manufacturer is most definitely not oxygen clean.

 

[Tigerman]

That's good advice. Even new tanks will require cleaning before being used with 100% oxygen. Be thankful that you are able to post and learn what to do next time.

Found this as food for thought.

O2 CYLINDER EXPLOSION - YouTube

HOLY HECK!!

And the comment from the poster of the video (found it on page 5) actually says the guy did not die
Lucky bastard..