Mailing List Archive Mailing List Archive
It seems to me that these two lists have a high population of people
suffering from Cerebralanalitus and other mental afflictions. Why is it
that people get these stupid ideas in there head and can=92t let go? One
such case is:
DEEP AIR.=20
FACT: Man developed to breath Air at the surface not underwater.
Air is NOT the best gas at any depth other that 0=92 fresh or sea water.
Nitrogen IS NOT physiologically inert!
Elevated PpO2 and PpN2 has a detrimental affect on human physiology.
FACT: Nitrogen is a NARCOTIC!=09
Pressure elevates the narcotic effect of Nitrogen.
Narcosis brings about a sense of well-being.
Narcosis impairs judgment.
Narcosis impairs memory
Narcosis increases response time.
Narcosis reduces motor skills.
FACT: Nitrogen is a POOR choice of gases from which to decompress
Nitrogen is a LARGE diatomic molecule making it more difficult to off-gas.
When chilled the body retains Nitrogen in much the same way a chilled soda
retains CO2.
When re-warmed Nitrogen escapes form the tissue rapidly (one major cause
of delayed onset DCS).
Nitrogen off-gases 2.6 times slower than Helium
Okay so what does all this mean. Air is a poor choice of underwater
breathing gas in MOST cases. Down to 60=92 or so in NON-decompression divin=
g
air is cheap and functions adequately. Beyond 60=92 or in situations were
decompression would be needed on air, Nitrox makes more sense. The PpO2
should NEVER exceed 1.4 ATA for a bottom mix (Nitrox or Tri-Mix). Keeping
in mind that long bottom times and/or extended deco may require lower PpO2.
Evidence shows that Oxygen is also narcotic. In fact it has been shown
that Oxygen is as narcotic as Nitrogen. That fact should be considered
when choosing your bottom mix. Any nitrox mix has an equivalent narcosis
depth that is equal to the depth at which it is used. IF, and that is a
big IF, you feel that you can handle a END of 150=92 a Nitrox mix of 24/76 a=
t
158=92 does not qualify! =20
Now as for 130=92 and deeper on air, even if you think you can handle the
narcosis (you are probably to impaired ,even at 130=92, to determine how
impaired you really are) the question of SAFE decompression becomes a
bigger issue. At 130=92 you have only 8-10 min NDL. Using a 28% Nitrox (se=
e
diatribe regarding PpO2 for bottom mix) you get 10-15 min NDL (depends on
who=92s tables you trust). Now I don=92t know about you but I don=92t see t=
he
point of a 15 min dive to most depths I would dive. =20
So now that decompression enters the picture take a look at what gas will
get you out of the water SAFEST. You have already committed to being in
for a while so how long is only a minor issue. Take a quick look at three
dives to 158=92 for 30 min. on three different gases, Air, EAN 24, and 24/16
Tri-Mix. Using EAN 84 from 30=92 to surface (forget the 80% vs. O2 flames. =
I
am making a point, and I don=92t care right now).
158=92 for 30 min on air. Total run time 60 min PpO2 and End fo=
r
bottom mix 1.21/158=92=09
158=92 for 30 min on EAN 24 Total run time 57 min PpO2 and End fo=
r
bottom mix 1.39/158=92
158=92 for 30 min on 24/16 Tri-Mix Total run time 56 min PpO2 and End
for bottom mix 1.39/127=92
Lets see now Slightly shorter deco and reduced END using a gas that will
off-gas more safely=85 Hummm? No one told you about that did they?
Look at what happens when you try three deeper dives 250=92 for 30 min on
Air, on 16/84 Nitrox (this is how Nitrox got started you know) and 16/43
Tri-Mix. Decompressing with EAN 36 from 110=92 and EAN 84 from 30=92.
250=92 for 30 min on Air Total run time 120 min PpO2 and End for
bottom mix 1.80/250=92
250=92 for 30 min on 16/84 Nitrox Total run time 132 min PpO2 and End
for bottom mix 1.37/250=92
250=92 for 30 min on 16/43 Tri-Mix Total run time 125 min PpO2 and End fo=
r
bottom mix 1.37/128=92
It is also interesting to note that on Air the CNS % ended at 199% after
the dive. On mix it was 82% and on 16/84 Nitrox it was 84%. =20
When you look at dive planing in this light it is clear that AIR (pardon
the pun) SUCKS WIND!!! I managed to figure this out before I my third year
of diving. Even before I took deep air (to 130=92). Clear unless you suffe=
r
from Cerebralanalitus or other mental afflictions. So please take your
head out of...... you know were, before some politician feels the need to
legislate us all out of our hobby that we enjoy!
Bill <Aquadart> Bott
"A human being should be able to change a diaper, plan an
invasion, butcher a hog, conn a ship, design a building, write
a sonnet, balance accounts, build a wall, set a bone, comfort
the dying, take orders, give orders, cooperate, act alone,
solve equations, analyze a new problem, pitch manure, program
a computer, cook a tasty meal, fight efficiently and die
gallantly. Specialization is for insects."
-- Robert A. Heinlein
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