On Mon, 10 Jun 1996, Peter N.R. Heseltine wrote:

> Bret Gilliam has sent me a letter further detailing his opinions on pPO2
> limits when diving and his opinions of me. I will spare you his
> intemperate ad hominem remarks, but would value your thoughts on the
> following two points he makes, particularly in view of other posts on this
> thread.
> 
> Bret says:
> 
> "If you don't like the exposures that I have detailed, I suggest you take
> your case to the US Navy and NOAA from which my notes were derived. Oxygen
> exposures are "dose" related, not simply partial pressure, as anyone with
> a shred of experience understands. And you can exceed a dose limit at 1.3
> ATA just as easily as you can at 1.6 or any other setting you might
> choose."
> 
> By this, and our telephone conversation, I infer that he means dose *and
> time*. i.e., that a certain minimum time at the dose must pass (e.g., 45
> mins at 1.6 ATA for a single exposure) in order for toxicity to occur. Are
> you concerned that O2 "hits" are possible in persons who have not exceeded
> their CNS clock at pO2s between 1.3 and 1.6 ATA?
> 
> Bret also says:
> 
> "The flow rates on the (Atlantis I) mechanical injection of nitrox gas
> considerably exceed any conceivable metabolic consumption of even the most
> conditioned high performance athlete."

bullshit, horseshit and all that crap, they didnt even KNOW the flow rate in
nassua.. maybe they know that know but there is no way this is gonna happen
unless you just free flow the gas into the breathing bag and then you 
have  about five minutes..  what  aa crock.  this is the problem when you
have a dive profesional moving into a "sales" position, some will say
anything to sell their product.  i understand that they are giving the units
away now.  like for contests or something.

someone needs to listen to what Peter is saying, and what Tracy has been 
saying for five years.  semi closed units do not work, (unless they have a
manual bypass for gas injection and a ppo2 indicator).  everyone that ever
gets their hands on one of these units are not going to be stupid, and they
are gonna figure it our very quickly, then they are gonna be pissed that they
didn't buy a fully closed unit (oh yeah, rich, you were right too, you told
me, about a million times, very nicely, the same thing).

listen or read very closely to me.. i have just about had enough crap 
about this issue and i am about to pop.  i wish i had the time to tell you
all of what really happened in nasssua, i can't believe that the other guys
out there don't have the balls to tell the truth.. but this is just a small
part... i don't want anyone mad at me, i just want people to live and get 
what they pay for (and what they think they are paying for)..now pay 
attention:

we had at least four or five hypoxic events on the dragers, mine (and 
others i would expect) was due to not purging before ascending from 90
fsw to 30 fsw.  also without out indicators on the units how the f**k does
he know what he's runing in the unit... you saw my tests on the fieno, it
takes SIX MINUTES TO RUN HYPOXIC UNDER A HEAVY LOAD, this is of course at
one atm, but just think if you were going up a line in a heavy current or
paniced and heading for the surface...  yes the drager is biger in all 
accounts, but to say that you cannot over breath the unit is pure crap.
it is a constant mass flow device, not regulated by the breathing load.

if any of you are even thinking about getting a rebreather.. do yourselves
a favor and STOP CONSIDERING A SEMICLOSED UNIT, you will be very 
disssappinted, to say the least, then you will have to sell it to your friend
knowing it's a piece of shit.

the worst part of this semi shit (you guys know who i'm taking about, and if
your reading this and it's pissing you off i want you to know that i 
don't give a crap, you are lieing to everyone) is that you are gonna put 
these
units out on the market and it's gonna give the whole industry (which 
some of us have spent four years working daily to make happen) a bad name,
they are going to think they are buying a for real rebreather and they are
gonna get somehting that isn't what they think they are gettiing.. period
 
then they are gonna think all rebreathers are the same..  and on top of that
PEOPLE ARE GONNA DIE CUZ THE UNITS WON'T KEEP UP WITH THEM, yeah i know, they
will die with fully closed units too, but it wont be the same.

well, i have just began, but you are waisting my only nice day this week and
my cbr900rr is calling.  if you want to hear more must piss me off again.




> 
> The manual (Joe Odom, 1995, rev 1, 3/96) used by TDI in training/
> certifying divers for the Atlantis I indicates that the currently
> available 7.6 L/min constant mass flow valve using (recommended) EAN50 on
> the unit delivers an FiO2 of 32% at a VO2 of 2.0 L/min and an FiO2 of 35%
> at a VO2 of 1.75 L/min, using the standard equation.
> 
> But, as noted in a previous post by Bernie Woolfrey:
> 
> "Diving and Subaquatic Medicine", quotes O2 metabolic rates (VO2)
> as ranging from between 0.8 L/min to over 3 L/min, with rates of over
> 2 L/min "quite common" (these are based on swimming tests, breathing O/C air).
>         The book goes on to say that:
>         Typical gas consumption rates for a "slow swim" 0.5kt, a diver
> would be breathing about 20 L/min of air, with an O2 consumption of
> about 0.8 L/min, and
> 
>   0.8 Knots     =       30 L/min air breathed =  1.4 L/min O2 consumed
>   1.2 Knots     =       50 L/min air breathed =  3 L/min O2 consumed.
> 
> This is an FiO2 of 17% at 3 L/min and an FiO2 of 13.6% at 3.2 L/min. Do
> you consider that VO2s in this latter range and higher are likely to be
> reached by a high performance athlete?

again, so right, the numbers don't lie. and they dont know the flow rates
anyway, at least we didnt in nassau, no one had a flowmeter.....  and if you
have this hight flow rate to keep up with a heavy load you are basicly on
open circuit....

IS IT THAT HARD TO UNDERSTAND OR  DOESN'T ANYONE CARE THAT THERE IS ALL THIS
BULL SHIT RUNNING AROUND OUT THERE JUST TO MAKE SOME MONEY.  I JUST DON'T
GET IT.

if you want a rebeather either buy a biomarine, or a cislunar.  they both 
will
have units for sale this years... BELIEVE ME YOU WILL BE VERY GLAD THAT YOU
HAVE WAITED AND SPENT THE SMALL AMOUNT MORE FOR THE FULLY CLOSED UNIT.

dp


> 
> Bret is apparently e-mail challenged at present and I will send him the
> above in a letter. As I have written before, I am not an "expert" but a
> recreational diver with some advanced training. As a physician who
> advises sport divers on health and diving medicine issues, my interest
> lies in accurately informing the divers whom I examine on safe diving
> practices and reasonably gauging my own diving risks.
> 
> Thanks for any replies you may send,
> 
> Peter Heseltine
> 
> 
> 
> 

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