Mailing List Archive Mailing List Archive
Hyperoxides, free radicals , oxidizers - the bottom line is that the damage done by exposure to higher ppo2's is a result of all three: in compounds formed, in brain chemistry altered and depleted, and in bunrt ( oxidized) lung tissue. There needs not only to be a good reason to use this stuff, as Nigel suggested, but the proper methods of using it to mininimize damage. We have al lot of that worked out, and I see it done wrong almost everywhere else. Some of you guys may be more knowledgeable types when it comes to chamistry and all, but the vast majority of those out there either are not, or are so misinformed by the 7/11 clearks who teach diving that they are hurting themselves without knowing it . Need a good reason to use it, need to know how to use it. Riedel, Paul E. wrote: > > Bill: The free radical comes from oxygen that has been chemically transformed. > The more oxygen the more free radical. Seems to make sense to me. > > At 08:46 PM 6/6/97 -0400, you wrote: > >At 06:40 AM 6/6/97 -0700, you wrote: > >>Frankly, I thought Nigel's comments raised some interesting questions > >>not only about the use of oxidizers but the use of low percentage > >>helium trimixes for conventional shallow diving. > >> > >Bob, > > > >Nigel's comments do raise a question about the use of high fO2 breathing > >gasses such as nitrox. The problem is that he has confused oxidants with > >Oxygen. Free radicals (the little buggers antioxidant destroy) are NOT > >Oxygen. They are molecules that have one or more extra electron. They > >readily "give up" that extra electron in a chemical reaction known as > >"oxidation". There is a second part to the "oxidation" equation, that is > >"Reduction". This type of reaction results in a covalent bond between two > >or more atoms. There is no need for Oxygen to be present for "oxidation" > >to take place. For example NaCL (salt) is formed when one atom of Sodium > >(Na) is "oxidized" by one atom of Chlorine (Cl) which is "reduced". Again > >this has nothing to do with Oxygen! > > > >Nigel is right on target about the effects of antioxidant vitamins and > >current medical thinking with regard to cancer and other disease. However > >he was unable to differentiate between Oxygen, an element, and oxidation, a > >chemical reaction. I don't believe Nigel fully understands nitrox, He > >wouldn't use the expression "ultra hyperoxic" for a nitrox mix if he > >understood. > > > >Here is a little different twist on the "Nitrox vs. Tri-Mix" debate. For a > >moderately deep dive say 160' why not use a Tri-Mix with a 24% fO2 and > >15-25% He. Or for a 120' dive how about a 30% fO2 and 10-20% He. If you > >run tables using many (if not all) of the available deco software, you > >will find a very similar profile to Air if you use nitrox for > >decompression. These are EXAMPLES ONLY!! I DO NOT SUGGEST USING ANY GAS > >MIX WITHOUT PROPER TRAINING AND UNDERSTANDING. > > > >I know there are still many misconceptions with regard to nitrox. And many > >more with regard to Tri-Mix. If nitrox and Tri-Mix scare you, don't use > >them. But whatever your choice for a breathing gas is, understand your > >choice and why you made it. Because "my instructor said so" is not > >understanding! > > > >>>A quote from Nigel, > > > >>>I was in the chemist yesterday and I couldn't help but notice that > >almost one entire aisle of the store was devoted to antioxidant > >vitamins. Let's see: there were all sorts of vitamin Cs, vitamin Es, > >vitamin A , B complexes, pynxogenol, mineral supplements and to top it > >all off hormones like melatonin which spposedly has mega antioxidant > >powers. In fact the whole thrust of the anti cancer and anti aging > >crusade seems to be oriented around the power of antioxidants in > >preventing free radicals from damaging connective tissue and DNA. Many > >physicians now agree that colon cancer as well as arteriosclerosis are > >preventable through a proper diet, high in antioxidants.<< > > > >>>When this as a backdrop why on earth would anyone in their right mind > >voluntarily expose themselves to a ultra hyperoxic breathing mix unless > >it was absolutely necessary. I would love one of you Yank diving rocket > >scientists out there to tell me that oxygen is not an oxidizer if you > >breath it (while you busily oxygen clean tanks and replace buna o-rings > >with Viton). Instead of boosting the oxygen content of the breathing gas > >I would lower it and replace it instead with an inert gas such as > >helium. Nitrox I should really be 12 - 14% helium and 19% oxygen. Nitrox > >II should be slightly higher helium and lower oxygen still. I am not > >advocating this for deep diving either (Deep diving for me is another > >whole subject). This is strictly my suggestion for a physiologically > >more healthy mix. Helium is a very rapid diffusing gas and transits the > >tissue rather quickly for low to moderate exposure dives. Weigh the > >advantages: reduced ppo2, reduced ppn2 (bad for those red blood cells > >and capillaries) and reduced deco (if you don't have a pfo). << > > > >>>Helium is bloody expensive in the UK and Oz, but when you keep the mix > >to 10 -14% on an 80cf tank you can get as many as 30 dives out of a > >290-300cf cylinder of helium when you cascade several. Even at $200 > >U.S. per cylinder this works out to 6 - $10 additional cost per dive. > >Big deal! Look what dive charters cost these days and with the weather > >in the UK being typically bad all of the time, how many weekends of > >diving do you actually get anyway. We spend more on petrol driving to > >the port of embarkation.<< > > > >Bill (aquadart) Bott > > > Paul Riedel > 570 Highland Av > Milford, Mi 48381 > > 1-800-426-4087 -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send list subscription requests to `techdiver-request@aquanaut.com'.
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]