Mailing List Archive Mailing List Archive
---- Forwarded message follows ---- Date: 15 Mar 96 00:24:35 EST From: "R.W. Hamilton" <70521.1613@co*.co*> To: David Doolette <ddoolett@me*.ad*.ed*.au*> Cc: Quiet_Frogmen <quietfrogmen@bt*.co*> Subject: Re: [QF]: oxygen decompression (cave diving) Message-Id: <960315052434_70521.1613_CHK38-2@Co*.CO*> Sender: owner-quietfrogmen@bt*.co* Precedence: bulk Responding to your question about why people are using enriched air 80% oxygen for decompression instead of pure oxygen. I am not entirely sure of the politics here, but I think I know the physiology. As you know, oxygen at 6 msw or 20 fsw is just a tad above the NOAA limit of 1.6 bar/atm. I think this has "scared" some IANTD types and they (read Tom Mount) have devised this scheme to reduce the PO2 and, presumably, the risk. In my opinion, which you suggest, the OEA80% (even at 9 msw/30 fsw) is not as effective for decompression as pure oxygen. If the PO2 seems too high at 6 msw, I think it would make more sense to stay at that pressure for say 10 min, then ease up to 5 msw or 4.5 or even 4 for the remainder of the shallow stops. The effectiveness of oxygen breathing is more or less the same at all these depths. This way you get the benefit of breathing pure oxygen, you can reduce the PO2 however you want to, and you do not have to fool with another mix, with all the hassle and risk that that entails. Now, I try to learn all I can about this and there may be something here that they know that I don't, so I am eager to hear more. It is true that you are at risk decompressing at 6 msw, as the Starfish Enterprise experience last June showed us (an O2 hit at about 50% of the so-called limit fraction or CNS%). But I think going shallower is better than reducing the oxygen in the mix. By the way, David, thanks for the plug about the Hobart meeting on oxygen. It seems oxygen is heating up, no pun intended, with renewed interest by DEMA and by the British HSE, among others. I hope to learn a lot at that meeting. We also hope to have a good session on Technical Diving. But don't forget the SPUMS meeting in late April, where David Elliott and I will rip techical diving apart in front of all the critics. I'm really looking forward to this one. Hope you are there. ---------------------------------------------------------------- Comments or questions: <owner-quietfrogmen@bt*.co*>
Navigate by Author:
[Previous]
[Next]
[Author Search Index]
Navigate by Subject:
[Previous]
[Next]
[Subject Search Index]
[Send Reply] [Send Message with New Topic]
[Search Selection] [Mailing List Home] [Home]