Yes, am I wrong ???

But I still haven't got an answer to my question

Mike

-----Original Message-----
From: Jesse Armantrout <armantrout@wo*.at*.ne*>
To: M.S.Langborg <findir@an*.co*.uk*>; Joel Silverstein
<joelsilverstein@wo*.at*.ne*>
Cc: techdiver@aquanaut.com <techdiver@aquanaut.com>
Date: 24 November 1998 21:48
Subject: Re: 80% arrrgh!! was Re: On the left


>Then do you think it is that all of the "major" divers use 100% ?
>
>----------
>> From: M.S.Langborg <findir@an*.co*.uk*>
>> To: Joel Silverstein <joelsilverstein@wo*.at*.ne*>
>> Cc: techdiver@aquanaut.com
>> Subject: Re: 80% arrrgh!! was Re: On the left
>> Date: Tuesday, November 24, 1998 12:28 PM
>>
>> 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
>> >
>> >
>>
>> --
>> Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
>> Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
>
>

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