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Tom Wylie writes:

>I cannot seam to fit an alogrithum( polynomial, expon) to the 
>pp02 verses %CNS data between ppo2 0.6 -> 1.82 with any
>degree of accuracy to the tables stated in the IANTD advanced Nitrox
>Manual.

I assume this is the same table that was in the old IANTD technical workbook,
i.e., %CNS exposure per minute at given level of PO2.  If so, then the reason
you can't approximate it as a simple mathematical function is that it does
not derive from a such a model, but rather is based on empirical data
(namely, the NOAA CNS exposure tables).  For example, the NOAA limit at
PO2=1.6 ATA is 45 minutes, hence each minute at PO2=1.6 yields 1/45 = .022 or
2.2% CNS. 

You can verify this fact by direct computation, but if you want my source of
this info, it is Randy Bohrer (who developed the table in my workbook for Tom
Mount).  

John
heimannj@ma*.nd*.gt*.co*

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