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On Thu, 7 Dec 1995, Todd Leonard wrote:

> 
> that describes a system for producing de-nitrogenated air nitrox (DNAx)
> by filtering an adjustable fraction of Nitrogen from air.  The benefits
> of DNAx to the diver are described much as those of EANx.  They also list
> benefits to th operator doing the fill, primarily in terms of safety and
> simplicity by avoiding high-PPO2 blending.
***this is one of the methods used to produce medical O2-by filtering out 
the nitrogen(from air) and discarding it> 
> They make no mention of whether the system filters out any of the less
> common gases present in air (mainly argon and CO2).  If it does not, then 
> clearly the fraction of those gases in the resultant DNAx mix would be 
> higher than in an otherwise similar EANx mix.  The effect would presumably 
> increase with the targeted FO2 of the final mix.  So, does anyone know...
> 
>   - whether the less common gases are filtered out?
> 
>   - how great a fraction of N2 can be removed, and therefore
>     what the resultant fractions of argon and CO2 would be if
>     in fact this effect occurs?
*****it reaches a max purity of about 98%O2
>   - whether there is any significant effect on the diver?
> 
> I am mainly wondering about altering decompression penalties with the
> argon, and increasing risk of hypercapnia with the CO2.  Worst case, 
> if none of the argon and CO2 are removed, I am thinking of fractions
> in the neighborhood of 3.6% argon and .13% CO2 in an 80% O2 mix.  That
> doesn't seem too horrible, but I figured I'd ask anyway.
> 
> Thanks.
> 
> - Todd
> 
> p.s.  Calculations are based on my assumption that the fraction of
>       argon and CO2 would increase linearly with the fraction of the
>       oxygen.  Therefore...
> 
>       .934 * ( 80 / 20.946 ) = 3.6
>       .033 * ( 80 / 20.946 ) = .13
> 
> 
> --
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> 

                         Bob Favorite RVT          
UC Davis VMTH              UC Davis SCUBA          The Octopus' Garden
VMD 490 Instructor          safety diver               safety diver

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