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Hi George and everyone else,

In a previous post you said something about how you prepare trimix.
I've long ago deleted the post (sorry) but I remember you saying
that you prepare and O2 analyise Heliox, then blow air on top, and
analyise again.  Target is set to provide a PPO2 of 1.4 at the deepest
expected point.  You also said something about Heliair that made
me think you very much scorn it's use.

Given all that, what do you do for dives between 180 and 200 ft.
For those depths a stacked trimix is so close to 21% (within 1%)
that your analyiser (which only has a resolution of 1%) can't tell
you *anything* about your final mix.  Indeed for an even larger
range of depths, the resolution is so low that almost no information
is available from O2 analysis.

This is the reason that I've only ever used Heliair.  I just can't
see how you can get a reliable (or faintly credable) idea of your
He/N2 ratio if you blow air (21%) onto Heliox.  How do you get
around this problem without using pure gases.  (ie, He first, O2
second, analyise, then pure N2, and reanalyse)

Cheers Jason =:)

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