Posted to DIR_UK

For those not on freeattic (the wkpp list) - George produced this email
on cylinder marking etc .  I have edited out the "emotional bits", this
editing was without his permission :-o

also I have added a UK slant to it

bottle marking, mixing, and analyzing 
   
                         ***********

1) bottles are free of "clutter" and stickers (as much as possible - in
the uk we will still need a VIP and some shops will insist on the std
IANTD stickers, if you are using these,for deco gas get the rights
ones, IANTD do a decompression gas and a oxygen one - these are 10 * 4
and are a lot tidier than a EAN cylinder sticker - if you decide just
to have a VIP sticker you run the potential of a dive shop not filling
your cylinder - this is your call) , they are marked
horizontally in the orientation of the tank on both sides as to the
maximum operating depth of the bottle according to 1.4 ppo2 for dive max
and 1.6 for deco max and 120 (fsw aka 36 msw) "AED" max for deco 100
(fsw aka 30 msw) "AED" max for dive. (Note : AED is air equivalent
depth and is the narcotic depth of the gas - as you can see they do not
dive high n2's and use AED as well as po2 in selecting all gases, inc
deco gases)
these numbers are at least 3" high ( so all buddies and diver can read)
and are painted on. They can also be taped on, but this is a less
attractive option since it takes seconds to knock off a painted marking
with PVC cleaner and repaint. I paint.

**** Standard deco mixes are preferred, as the optimal
decompression mixes have long ago been worked out through thousands of
man dives. As you know, they are 100%,50%, 35% ( usually with 25%
helium)  and 18/35 ( vestigially referred to as "air" by the WKPP). This
reduces chances for error, and again, the optimization of deco gases is
far more complex than just ppo2, and a topic in itself.*****

The point is simplicity and safety

a) back gas needs to be labeled( mix, analysis, dated and pressure
noted) in storage or transport. Deepest gas is always on the back. Back
gas is re labeled after each dive, even if it is going to be dumped.

B) all tanks must have name of diver on them.
 
C) argon must say "argon", oxygen must say "oxygen" ( because 20 can
look like 70) - (we have an advantage as we use Oxygen at 6m, which
cannot be confused with another depth,  however I'd mark with the word
Oxygen as well) . We do not inflate BCD's with argon ever.

2) regulators - are all the same . We do rely on identification of gases
by any other means than mentioned above. We do not give ourselves any
further chance to make a mixup and breath the wrong gas. If we are not
able to identify a gas, we do not breath it.

3) mixing - first check the storage bottles to see if they are argon or
helium with no oxygen, and the oxygen for 100%, and smell both.

    A) bottle is mod marked and emptied. Two pieces of tape are applied
to the neck. One will be for the immediate contents, one for the final
analysis.

    B) we add a gas. Without removing the whip, we write the date and
the psi (bar) of that gas.

    C) we add the next gas. Without removing the whip we write the psi
(bar)
of that gas.

    D) for warm fuzzy, we can analyze now, but not really necessary

    e) we go add air (or if we have haskelled heliox) we analyze the
final product, and on the other piece of tape we write the date, the %
oxygen, and the % helium ( based on the psi (bar) of the bottle knowing
the
original addition or analysis). We take the original piece of tape and
tape the bottle valve to indicate that the bottle is full and ready to
dive.

                  What does this leave us with?

 
    To deploy a gas, we look for the correct bottle based on the mod. We
unstow the reg and put it in our mouth. We then go back and turn on that
correct mod bottle. If we can now breathe, we are breathing the right
gas.

    Since our long hose is the one we breath from the doubles and is
easily identifiable as such and the backup hose is hung around the neck,
we are not going to get back onto the wrong reg there, are we? If we
came off of a stage, we turn it off and stow the hose so as to not
confuse them ever. This is standard operational procedure.



© 1997-2005 Greg Roach, all rights reserved.