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Can someone out there give me the straight scoop on O2 cleaning?  Every gear
manufacturer and agency seems to have different regulations and standards
ranging from cautious to downright paranoid, and I'm getting frustrated as
hell trying to sort it all out.

My specific areas of concern are:

1.  What exactly needs to be done to a regulator to make it safe for
mixtures of 40% to 100%?  (Beyond the tear it down and clean everything with
simple green, trichloroethane, or other solvent part.)

     a.  Does every O-ring need to be viton, just high pressure side, or are
nitrile/butyl o-rings acceptable?  I know that many aviation applications
use nitrile, but viton seems to be mandated for scuba uses.  What's the
deal?

    b.  What needs to be done with hoses, especially HP?  ( clean them, use
new hoses rated for O2 service, etc.)

    c.  SPG's: Should they be cleaned, and how?  Do the spool O-rings need
to be changed?

    d.  Second stages: Do the O-ring, diaphragm, and seat materials matter
at the lower pressures that this system is exposed to?  How about lube?

    e.  Are Sherwood regs (with the rubber dry air bleed valve) acceptable
for use with high FO2's?  (academic question--I use Zeagles)

2.  Tank valves:  Do quick opening valves, like some Genesis K's with coarse
threads on the seat, pose a danger with high FO2's?

Any help from those with more experience in this are would be greatly
appreciated.  I have used and been around HP O2 in welding and cutting
industrial applications for years, and despite some abhorrent conditions of
uncleanliness and regulator (welding type) abuse that I have been
unfortunate enough to witness, I have not seen or heard of any documented
accidents besides the " My brother's wife's friend's brother knew a guy who
heard of somebody...." type.  It makes me wonder how much of this is
actually necessary and how much is scare tactics to get divers to buy viton
everything.
    Don't get me wrong, I've been pretty cautious up to now with the mixes
under 40% that I have used, but I'm just curious as to how much of this is
necessary, and how the folks out there who have the experience are doing
things.

Thanks in advance,

Duane

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