Posted by MHK on November 17, 2000 at 09:46:44:
In Reply to: Re: P.S. posted by AADIVER on November 16, 2000 at 22:58:51:
John's point is that from a purely comparitive point of view that He is safer the N2.. In a perfect world to the extent that you could it would be more beneficial to use He rather than N2.
Having said that you need to truely evaluate the differences and the respective options for dives 100' or less. We recommend Nitrox for these dives, but some of our friends are going strictly to Heliox.. By using a Nitrox mix and thus elevating the F02 and reducing the FN2 you are replacing the unfriendly gas ( ie; Nitrigen ) with some 02. Of course we know that N2 is one of the main contributory factors in DCS.. Generally when you look to each specific tissue group it's the slow ( or fatty ) tissues that tend to retain the N2.. Studies are finding that He is a much friendlier gas and it *offgases* 2.65 times quicker than N2. Add that to the related benefits associated with END ( Equivalent Narcotic Depth ) and you find that you have a clearer head, you will have less of a chance for a C02 buildup and you will have longer available BT's and shorter SIT's..
So from a strictly comparitive perspective, in other words a dive done on Heliox -v- a dive done on standard compressed air you would be safer on the Heliox.. But you then need to be realistic and look to the limited number of DCS and speak to the practicality issues.. For the average diver who dives a few dive's on the weekend is it worth the time and expense???? Every person needs to answer that for themselves...
But to the extent that you are making a living ( ie; in the water day in and day out ) these are some considerations.. Moreover, there is substantial data respecting the long term damage to the red blood cell rigidity with extended exposure to N2..
As to who pumps He, most of us use Jim Hoffman at Scuba Toys.. Jim's prices are more than competitive and your fills are always accurate...
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