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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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