Return-Path: <greiner%eccx.dnet@esu36.cfsat.honeywell.com>
Newsgroups: bit.listserv.scuba-l
Date:         Sat, 7 Nov 1992 06:06:39 -0700
From:         "(Everything you know... is wrong!)"
              <greiner%eccx.dnet@ESU36.CFSAT.HONEYWELL.COM>
Subject:      HOME-BREW NITROX

>Jeff Wall writes:

>\I have taken the NITROX class (IAND) but I have not done my
>\dives and recieved my card.  The impression I got from class
>\was that filling a tank with a higher percentage O2 was not
>\necessarily the problem.  The problem came when divers put in
>\the pure O2 took the tank to the dive shop to be filled and
>\then went diving later that day.  I was taught first you shouldn't
>\homebrew but, if you mix the gas by diffusion it takes from 4 - 5
>\days for the O2 and the air to mix uniformly.

>\Therefore, if a diver goes diving later in the same day he has
>\his tanks filled he could be at say 90 fsw. and take a number of
>\breaths of almost pure O2. Since we all know the max depth on pure
>\O2 is around 20 fsw. this could cause some problems in an extreme
>\situation.

>No, no, NO !!  Not true.  If IAND is teaching this, it is utter
>garbage.  Do not believe it.  Even under ideal (totally nonturbulent)
>conditions, mixing of O2 and N2 will go very quickly in a tank (few
>seconds).  Add a bunch of turbulence, such as will always be the
>case in a real tank, and the mixing is virtually complete when you
>shut the valve.
>
>             OOo O                John Geary
>             O oO                 PADI DM-52283
>              o                   geary@cfa.harvard.edu
>       _____ o o
>      (_/-\_)..
>     ===(O).

First thing I would like to say is In agree with John Geary, mixxing of
gasses is almost instantanous - look into rebreathers.

Second thing is just this - what exactly are people defining as
NITROX ????  It appears to me that people are starting to missuse that
word as badly as the word "WEIGHT."  NITROX in actuallity is nothing more
standard tank of compressed air which any scuba-shop I am sure will gladly
take $5.00 to fill it for you.  However what you are doing is defining NITROX
as is ENRICHED AIR (not to be confused with each other).  My point is this
1) Enriched air both home-brew or retailed by trained people is dangerous
   in many repects.  How can you regulate the amount of O2 from pure and mix it
   with compressed air - and then say,"Yep, yessiree Bob, this is just right
   I think I will just hop in water here see, and check out if I don't spaz
   out with siezures from over doing the good 'ole stuff O2."
2) If the body was meant to breath pure oxygen don't you think that our body's
   would be a little more efficient in removeing inert gases from the air that
 we
   normally breath everyday.  Maybe that is the reason why humans cannot breath
   O or O3.
3) Why wouldn't you just go for a re-breather. Which does the same thing except
   it does its mixing underwater while you are breathing ENRICHED AIR.  I am
 sure
   Myself and family/friends in UDT/SEAL would more than try to talk people out
   of ENRICHED AIR.
4) If it is bottom time you want then go for dualies.  If it is depth and time
   and no one is always going to watch your limits except for yourself then
   don't put yourself in danger or buddy use something safer. I would recommend
   dualies with heliox, and standard compressed air tank for decompression.
 Helium
   is much more safer than adding oxygen

Hans
Comments: Gated by NETNEWS@AUVM.AMERICAN.EDU