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>      I want to rig a small O2 bottle for a shallow decompression gas. Can 
>      anyone help me out?
>      
>      Should I purchase a medical O2 bottle and try to rig it with a scuba 
>      valve? Will either an old-style 1/2" scuba valve or a modern valve fit 
>      the O2 threads? 
>      
>      Or, should I detacate a small scuba pony for O2 use?  If so, how do I 
>      get the tank filled? 
>      
>      Will a welding supply store have the necessary adaptors to connect to 
>      scuba valve?  (I am assuming that welding O2 is as good as medical 
>      O2). 
>      
>      Luxfer has a tchnical bulletin that recomends that their scuba tanks 
>      not be filled with O2.  I suspect that they are trying to avoid 
>      liability.  Does anyone know if it really matters?

Probably the best way to proceed is with a scuba cylinder of the size 
that will meet and exceed your expected decompression by 2 times.  I've seen
both steel and aluminum used, so you may be correct in your assumption 
about Luxfer, but it wouldn't hurt to call them and find out why.

You will then need to have the cylinder and valve cleaned and made 
suitable for O2 service which entails cleaning and replacing all items 
not O2 compatable.  The cylinder will then be dedicated to O2 use and 
clearly marked as such.  Also, you might find it easier if you use a
Lower pressure cylinder.  In my experience, welding shops often refuse
to fill scuba cylinders for liability reasons.  Hince you will probably 
need to have it done at a dive shop or purchase a Haskell O2 pump $$$!

The regulator will also need to be dedicated and serviced for O2 as 
well.  Some regulators are easier to do this with than others.  I'd 
suggest that if your using this as a pony, that you get a 2nd stage the 
shape of which cannot be confused with any other second stage you have on 
you.  A lot of units have green covers for O2 which is fine, but at 
depth, or silt out, color doesn't mean much. It's real easy to grab the 
wrong 2nd and at depth, that could easily be a fatal mistake!  In fact, unless 
you are wreck diving, I'd suggest using it as a line stage bottle instead of
carrying it or as a side mount where the regs location is unique.  But 
then, if you are using O2, then you should already have been trained 
about that!

RW

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