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To: techdiver@opal.com (Techdiver Mail List)
Subject: Re: TDI? IANTD? Relationship?
From: "William E. Sadler" <yqwyktp@bl*.bs*.co*>
Date: Wed, 19 Apr 95 8:08:33 EDT
Frank,

>>Is IANTD Basic Nitrox NOAAI or NOAAII,Advanced is Any %O2 up to 50%, and Tech 
>> includes up to 100% in deco situations?  If this is so, then ANDI full user
>> is Advanced.
>
> When I went through my ANDI course, I was told that with the course, we were
> eligible for ANY O2 blend, right to 100%.
>
>-frank

This is exactly my question.  I suppose I should pose it to ANDI, but on p.17
of "The Complete Users Guide for The Application of Enriched Air Mixtures", 
4th edition, by Ed Betts, (c) 1992, says:

"SafeAir, defined by ANDI, is any enriched air mixture with O2 concentrations
between 22% and 50%.  The ANDI training program teaches the practical
applications of these mixtures for recreational/sport diving situations."

on p.46 the book discusses in water decompression w/ EAN mixtures.  The 
authors state that 100% O2 is often abused by deep air divers as a deco gas
since O2 pp at depth are not considered. (Authors state, not me!)  They go
on to state that if the deco schedule requires O2, use O2, don't try to 
2nd guess w/ 5 min air breaks, etc. but if O2 is not required, but desired for
safety, to use SafeAir 50 instead.

on p.49 there are a list of advantages of SafeAir50 over pure O2.

So, while it is 'taught' to higher mixes, it is taught mainly to NOT use
higher conc. of O2 than 50%.

In my course, there were exactly 8 methods of Nitrox use taught.

1) stay > 130', < 45 mins bottom time, NOAA I Nitrox, all else as air diving.
2) Nitrox w/ Air computer, and feel free to push the limits.
3) Nitrox w/ Nitrox computer.
4) Use NOAA Nitrox I or II tables.
5) Use EAD formula for the % O2 that you have
6) Optimize gas for a planned depth
7) Pony bottle w/ higher fO2 than bottom mix to use w/ ascents
8) Pony bottle w/ air, mains w/ Nitrox. (So you can chase deep students!)

The course did not cover modifications to decom schedules as a result of using
higher O2 conc.  w/ exception of EAD formula.  It occurs to me that using the
EAD formula would give you a lower decom. obligation.

on p.72 the book states:
"...the primary reason to use the EAD formula is to be able to use standard
air tables when the gas mix doesn't match the standard enriched air tables"

What does it all mean?  While EAD techniques are covered, decompression
dives are not covered, nor is use of > 50% mixtures covered specificaly.  
However, the info is there if you wish to use it.

Curiouser, and curiouser.  So, which IANTD course is the equivalent to the
course described?  TDI course?  Is there a different ANDI nitrox course that
I don't know about yet?

Later!
--
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/* William E. Sadler  | email:  sadler_b@bs*.bs*.bl*.co*                */
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