I will not speak for the others as this is an area where we are still
trying to come up with the best solution and so far we are all doing things
just a little different, but we are getting close to an optimal solution...

As you know, decos of over 8 hrs are common for the wkpp, with the final
"real" stop at 30 feet in a dry habitat on pure o2 for about 200 minutes or
so.  This means that we have to worry about CNS tox, of course, but also
pulminary tox.  To pull this off without destroying our lungs and seizing,
gas breaks are a must.  I begin 25 minutes into deco and go for 5 minutes. 
This means that my first break is at about 210, by the way.  I know 20 is
recommended, but I can keep track better if I do 25 and 5...in other words
my clock resets every half hour.  We have decided that it is best to break
to the lowest fo2 gas we have, in our case 10/60 or so.  As we work our way
on up, these breaks start getting a little longer, but I keep the interval
they same.  By 50 feet, I am doing 20 plus 10, and once in the habitat, I
change to like 15 and 5, and have gotten down to 10 and 10, depending on
how I feel.

We include breaks in the deco as we are finding it actually makes the deco
MORE efficient.  If you get to the point of pulmonary tox., you are screwed
because gas exchange goes to hell and your deco will be ruined.  The
results of CNS tox are obvious...your day is ruined.

Questions?

Trout

----------
> From: Nanci LeVake <nlevake@pi*.co*>
> To: M.S.Langborg <findir@an*.co*.uk*>
> Cc: techdiver@aquanaut.com
> Subject: Re: 80% arrrgh!! was Re: On the left
> Date: Tuesday, November 24, 1998 6:29 PM
> 
> Mike,
> 
> The standard answer would be to take a 5 minute break for every 20
minutes
> of O2 deco.  If your deco is 20 minutes long, put the break halfway
> through, and don't count it in your deco time.  
> 
> Some divers doing extended O2 deco will break after an even shorter time
> than 20 minutes.  It would be great if George or Bill Mee or JJ or any of
> those guys would explain how they manage breaks, I don't want to repeat
it
> inaccurately......
> 
> Nanci
> 
> 
> t 09:09 PM 11/24/98 -0000, M.S.Langborg wrote:
> >Since I am not disagreeing with you, is this your way to say: I don't
know
> >either??
> >
> >Mike
> >-----Original Message-----
> >From: Joel Silverstein <joelsilverstein@wo*.at*.ne*>
> >To: M.S.Langborg <findir@an*.co*.uk*>
> >Cc: techdiver@aquanaut.com <techdiver@aquanaut.com>
> >Date: 24 November 1998 19:46
> >Subject: Re: 80% arrrgh!! was Re: On the left
> >
> >
> >>So Mike -- lemme see if I got this right --- the training you recieved
did
> >>not cover oxygen exposure where "air" breaks are needed ?  Though they
had
> >>you use EAN80 instead of 100% oxygen ?
> >>
> >>Agencies dont teach --- teachers do and teachers who also get out there
and
> >>dive when not teaching do it even better. Nothing worse than a guy who
is
> >>always in a classroom.
> >>
> >>As far as the stroke mix is concerened I addressed that a few posts
back
> >>--- no need for is -- just use the correct deco mixes and life if easy.
> >>
> >>
> >>
> >>
> >>
> >>At 06:28 PM 11/24/1998 -0000, M.S.Langborg wrote:
> >>>No, as you know, all the "major" agencies teach deco using 80 %.
> >>>
> >>>Mike
> >>>
> >>>
> >>>
> >>>-----Original Message-----
> >>>From: Joel Silverstein <joelsilverstein@wo*.at*.ne*>
> >>>To: Mike Langborg <mslangborg@cl*.ne*>
> >>>Cc: techdiver@aquanaut.com <techdiver@aquanaut.com>
> >>>Date: 24 November 1998 02:08
> >>>Subject: Re: 80% arrrgh!! was Re: On the left
> >>>
> >>>
> >>>>yup   -- wasnt that covered in you training program?
> >>>>
> >>>>
> >>>>
> >>>>
> >>>>At 09:42 PM 11/23/1998 -0000, you wrote:
> >>>>>Ok, so 100% oxygen is the way to go. What do you do about
"airbrakes".
> >>>>>
> >>>>>When, i.e. after 20/25min?
> >>>>>for how long, i.e. 5/10 min?
> >>>>>And what gas do you use for "airbrakes" i.e your 50%, your 36% or
your
> >>>>>bottommix?
> >>>>>
> >>>>>Mike
> >>>>>
> >>>>>
> >>>>>
> >>>>>-----Original Message-----
> >>>>>From: Joel Silverstein <joelsilverstein@wo*.at*.ne*>
> >>>>>To: gwaw@ix*.ne*.co* <gwaw@ix*.ne*.co*>
> >>>>>Cc: Techdiver@aquanaut.com <Techdiver@aquanaut.com>
> >>>>>Date: 23 November 1998 16:23
> >>>>>Subject: 80% arrrgh!! was Re: On the left
> >>>>>
> >>>>>
> >>>>>>Dear Arnie,
> >>>>>>
> >>>>>>It is quite easy to pump 100% oxygen to 3000 psi -- the dive shop
needs
> >>>to
> >>>>>>make the investment in a proper oxygen service rated Haskel Gas
> >booster.
> >>>>>>Most any reputable dive center who is mixing gas for the consumer
> >should
> >>>>>>have one, anyone that does not should step up pet the pony and buy
one.
> >>>>>>
> >>>>>>80% EAN was not created from a decompression standpoint it was
> >justified
> >>>by
> >>>>>>those who did not have a gas booster. Here's why. Oxygen gets
delivered
> >>>in
> >>>>>>2400 psi bottles, (some major cities have gas suppliers who can
supply
> >at
> >>>>>>3500 psi) however you can cascade into a 3000 psi rated cylinder
about
> >>>2250
> >>>>>>psi of oxygen top up to 3k with air and you have 80% oxygen
content.
> >>>Simple
> >>>>>>enough.  However .......
> >>>>>>
> >>>>>>80% EAN limits you severely. 1. at 20 and 10 fsw its PPO2  is too
low
> >>>make
> >>>>>>it useful, at 40 fsw its too high for maximum exposure limits.
> >>>>>>
> >>>>>>10 fsw 1.04 po2  too low
> >>>>>>20 fsw 1.28 po2  too low
> >>>>>>30 fsw 1.53 po2  borderline
> >>>>>>40 fsw 1.77 po2  too high
> >>>>>>
> >>>>>>Where as 100% oxygen is
> >>>>>>
> >>>>>>10 fsw 1.30 po2
> >>>>>>20 fsw 1.61 po2
> >>>>>>
> >>>>>>(with the 10 fsw stop normally being taken at 20 fsw
> >>>>>>
> >>>>>>Advocates of the EAN80 (a/k/a stroke mix) have come up with a
variety
> >of
> >>>>>>reasons to justify not using 100% oxygen --- one of the great ones
is
> >>>"its
> >>>>>>good for divers who have trouble holding buoyancy at 10 and 20 fsw"
> >>>>>>frankly if a technical diver cant hold a 20 fsw stop --- they
should go
> >>>>>>bowling and get the hell out of the water.
> >>>>>>
> >>>>>>Most divers who are using accelerated decompression tables have
> >>>>>>standardized on their decompression mixes.  (some are finding that
> >>>>>>hyperoxginated heliox mixes are working well too though that is
beyond
> >>>the
> >>>>>>scope of this email)
> >>>>>>
> >>>>>>EAN 36 from 110 fsw
> >>>>>>EAN 50 from 70 fsw
> >>>>>>100% oxygen from 20 fsw
> >>>>>>
> >>>>>>Granted when you run one of the consumer dive profiling softwares
you
> >may
> >>>>>>see only a small decrease in decompression time -- maybe 5 minutes
by
> >>>using
> >>>>>>100% over EAN80. and though you may belive that is not a
significant
> >>>enough
> >>>>>>advantage to make sure you have 100% oxygen here are a few more
> >>>>>>non-scientific reasons.  From a mixing standpoint unless you are
using
> >>>>>>exceptionally clean hyper filtrated air or air produced from an oil
> >free
> >>>>>>compressor there is risk of explosion when mixing high pressure air
on
> >>>top
> >>>>>>of 100% oxygen. It probably has not happened yet --- but some day
some
> >>>>>>goober will blow up a building doing it. Even if you are using a 30
> >cuber
> >>>>>>(small) just cascading 2400 psi oxygen in it will give you 24 cuft
of
> >>>>>>oxygen -- for deco thats easily 40 minutes worth, which is a lot of
> >gas.
> >>>No
> >>>>>>need to goober around making EAN80 for the other 6 cuft, its just
too
> >>>much
> >>>>>>work for it and I am sure it costs a bit more, besides if you are
doing
> >a
> >>>>>>dive that requires much more than 40 minutes of oxygen
decompression
> >you
> >>>>>>would want a bigger tank. The fact that a tank has a pressure
rating of
> >>>>>>3000 does not mean you have to fill it to that level. I have an
> >excellent
> >>>>>>tank chart for all currently available tanks in the US on our web
> >site -
> >>>go
> >>>>>>look at it. Next; most consumer available oxygen analyzers using
> >>>>>>electrochemical sensors can be off by as much as 2% in their
readings,
> >so
> >>>>>>is your 80% really 80 or is it 78? Whereas pure oxygen is upwards
of
> >99%
> >>>>>>pure -- it's a known item.
> >>>>>>
> >>>>>>Arnie, as a techie in training you have an opportunity right in
front
> >of
> >>>>>>you. It's two roads ... the left road is filled with exploration,
> >>>>>>friendships, technology and long proven safety procedures. The
right
> >road
> >>>>>>is bumpy, full of mis answered questions, body bags, and strokified
> >>>>>>convolution. I get the feeling your want to take the high road and
do
> >it
> >>>>>>right. In Judaic studies we are taught to ask why not to follow
> >blindly.
> >>>>>>So in this very long winding response (If I had more time it would
have
> >>>>>>been shorter) the answer is .... EAN80 buys you 6 cuft more gas,
but
> >buys
> >>>>>>you nothing else. Take no shortcuts when it comes to technical
diving.
> >>>>>>
> >>>>>>Good Luck
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>
> >>>>>>At 10:21 PM 11/22/1998 -0800, you wrote:
> >>>>>>>Joel,
> >>>>>>>
> >>>>>>>Another question for you.  It is prompted by your post on the
bottle
> >>>>>>>marking issue.
> >>>>>>>
> >>>>>>>What is the advantage of 100% O2 compared to 80% O2.  I've been
using
> >>>>>>>the latter for deco.  For one, it is somewhat easier to get at
local
> >>>>>>>dive shops because it is harder to pump the 100% to 3,000 psi, but
> >that
> >>>>>>>is merely convenience.  More importantly, I can get on the 80% at
30ft
> >>>>>>>and have the advantage of breathing a higher gradient gas mix
sooner
> >>>>>>>than waiting to the 20ft stop.  The published tables I've seen
give no
> >>>>>>>time advantage to doing deco on 100% over 80%.
> >>>>>>>
> >>>>>>>What is your view and why?  TIA.
> >>>>>>>
> >>>>>>>Blow gentle bubbles,
> >>>>>>>
> >>>>>>>Arnie
> >>>>>>>Tech Diver in Training
> >>>>>>>
> >>>>>>Joel Silverstein
> >>>>>>Scuba Training + Travel Co.
> >>>>>>http://www.NitroxDiver.com
> >>>>>>--
> >>>>>>Send mail for the `techdiver' mailing list to
`techdiver@aquanaut.com'.
> >>>>>>Send subscribe/unsubscribe requests to
> >`techdiver-request@aquanaut.com'.
> >>>>>>
> >>>>>>
> >>>>>
> >>>>>
> >>>>>
> >>>>Joel Silverstein
> >>>>Scuba Training + Travel Co.
> >>>>http://www.NitroxDiver.com
> >>>>
> >>>>
> >>>
> >>>
> >>Joel Silverstein
> >>Scuba Training + Travel Co.
> >>http://www.NitroxDiver.com
> >>
> >>
> >
> >--
> >Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
> >Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
> >
> --
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