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Scuba Forum / General / May 2004Do any nitrox computers measure gas mix?
I just took a nitrox course and -- holy crap -- the gas mix changes as the temperature of my tank changes? I was wondering if any of the nitrox compatible air-integrated dive computers also acted as an oxygen analyzer (so that it can determine, dynamically, what your PPO2 is)? -- Wade Guthrie news@adventure101.com > I just took a nitrox course and -- holy crap -- the gas mix changes as the > temperature of my tank changes? I was wondering if any of the nitrox compatible [quoted text clipped - 4 lines] > Wade Guthrie > news@adventure101.com Who told you that? Can you provide a quote of that? Sounds like crap. >>I just took a nitrox course and -- holy crap -- the gas mix changes as the >>temperature of my tank changes? I was wondering if any of the nitrox > > Who told you that? Can you provide a quote of that? Sounds like crap. Once you have a mix of x% O2 and y% N2, you simply have it regardless temperature is, unless you don't go below a temperature the gas would start to condensate. This however will not occur in diving environment. I think that there is misunderstanding and the thing is about measurements made just after blending, when you will get possibly incorrect measurement result, so it should be done some time after (when gas cools down and is well mixed). Regards, Shrek There are a couple of dive computers that do measure PPO2 and adjust the deco accordingly. They are indented to be used with rebreathers. What makes you think that your mix changes with temperature? I think you should have a talk with your instructor. > I just took a nitrox course and -- holy crap -- the gas mix changes as the > temperature of my tank changes? I was wondering if any of the nitrox compatible [quoted text clipped - 4 lines] > Wade Guthrie > news@adventure101.com > There are a couple of dive computers that do measure PPO2 and adjust the > deco accordingly. They are indented to be used with rebreathers. What [quoted text clipped - 15 lines] >>Wade Guthrie >>news@adventure101.com Yeah forgot about rebreathers! > I just took a nitrox course and -- holy crap -- the gas mix changes as the > temperature of my tank changes? Take a GUE course and learn the truth.  Signature"We're going to rush the hijackers." -Jeremy Glick, aboard United Airlines flight 93, September 11, 2001 AMEN!!! Bubba ~~~_/) ~~~ On Apalachee Bay - The Pirate Coast Home of Billy Bowlegs and Mysterious Waters Wakulla County, Florida ~Wet Dreams~ Hull Number 158 In article <5mdo80tlr3u38t8dt1bumop5r8t4g4o66q@4ax.com>, Wade Guthrie <news@adventure101.com> wrote: ? I just took a nitrox course and -- holy crap -- the gas mix changes as the ? temperature of my tank changes? Take a GUE course and learn the truth. -- "We're going to rush the hijackers." -Jeremy Glick, aboard United Airlines flight 93, September 11, 2001 > ? I just took a nitrox course and -- holy crap -- the gas mix changes as the > ? temperature of my tank changes? > > Take a GUE course and learn the truth. Shouldn't that be the Truth? :-) > I just took a nitrox course and -- holy crap -- the gas mix changes as the > temperature of my tank changes? Not true. Brian Edmonton, Alberta > I just took a nitrox course and -- holy crap -- the gas mix changes as the > temperature of my tank changes? I was wondering if any of the nitrox compatible > air-integrated dive computers also acted as an oxygen analyzer (so that it can > determine, dynamically, what your PPO2 is)? Go back to your instructor, give him back his certification card and tell him you want your money back. You've been cheated. Do not buy anything else from him. You'll get cheated again. Most importantly, don't buy a computer from him. The gas mix does not change as the temperature of your tank changes. Trust me on this. You are clearly confusing the partial pressure or oxygen, which does change as pressure changes, with the mix, which does not. BTW, the partial pressure of nitrogen and all the trace elements in the gas you breath also changes. If this makes no sense to you, please, do not dive with nitrox until you've cured the ignorance your instructor left in his wake. Lee > > I just took a nitrox course and -- holy crap -- the gas mix changes as the > > temperature of my tank changes? I was wondering if any of the nitrox [quoted text clipped - 20 lines] > > Lee One factor keeping me from Nitrox certification is I feel the courses are a rip off. They are $300 here for the knowledge content of a thin book. Adam > > > I just took a nitrox course and -- holy crap -- the gas mix changes as the > > > temperature of my tank changes? I was wondering if any of the nitrox [quoted text clipped - 23 lines] > One factor keeping me from Nitrox certification is I feel the courses are a rip off. They > are $300 here for the knowledge content of a thin book. and the card. Some shops may not fill nitrox without that. Othewrwise, you're right. Dennis > Adam > One factor keeping me from Nitrox certification is I feel the courses are a rip off. They > are $300 here for the knowledge content of a thin book. Poor excuse. Just go out and find a cheaper one. They're around. Last time I looked, there was an on line course at http://www.americandivecenter.com/nitrox/n2o2_m00.htm#m43 . Personally, I think a nitrox course is worth it simply for the knowledge gained. On the other hand, I breath nitrox on pretty much every dive. Lee > > One factor keeping me from Nitrox certification is I feel the courses are > a rip off. They [quoted text clipped - 7 lines] > > Lee Thanks for the online course. I thought you need to show a Nitrox certification card to get Nitrox tanks? > Thanks for the online course. I thought you need to show a Nitrox > certification card to get Nitrox tanks? Not here. Signature"We're going to rush the hijackers." -Jeremy Glick, aboard United Airlines flight 93, September 11, 2001 > Thanks for the online course. I thought you need to show a Nitrox certification card to > get Nitrox tanks? It depends on where you go for your fills. Most places, you're correct. They want the card. That doesn't, however, mean you can't gain the knowledge for it's own sake. The course I pointed you to requires three things that have to be done at their location. You have to be shown how to use an oxygen analyzer and demonstrate your ability to do so correctly, you have to pass a written test and you have to pay your money, at least you do if you want the card. Lee > > One factor keeping me from Nitrox certification is I feel the courses are > a rip off. They [quoted text clipped - 7 lines] > > Lee I see that the course is reasonable but you have to show up in Florida. Know of any like that in California? Adam > I see that the course is reasonable but you have to show up in Florida. Know of any like > that in California? No, but that doesn't mean there isn't one. FWIW, I took a quickie, but face to face, course for just under $100 about 5 years ago. I learned the basics in the course, but supplemented it considerably by self study. Lee > On the other hand, I breath nitrox on pretty much every dive. Unless we're doing Trimix, aren't we all? Curtis > > On the other hand, I breath nitrox on pretty much every dive. > > Unless we're doing Trimix, aren't we all? Yes, but you know what I meant. Lee > > > On the other hand, I breath nitrox on pretty much every dive. > > > > Unless we're doing Trimix, aren't we all? > > Yes, but you know what I meant. Of course, as you know what I meant. ;-) Curtis >other hand, I breath nitrox on pretty much every dive. Pretty much? You're using helium now? --- Rich http://richlockyer.tripod.com/ > >other hand, I breath nitrox on pretty much every dive. > > Pretty much? > You're using helium now? No. I tried it on one dive, but that's it so far. I have four tanks that I don't get cleaned for nitrox. When they go in for annual inspections, they get filled with air. After that, I get two of them filled at a facility that banks nitrox and will fill them without hesitation. The other two are my wife's. She's not nitrox certified and has expressed a strong desire to continue as she has. Saved me the cost of a new computer for her. Except when using one of those tanks or when doing an impromptu dive using a rental or somebody else's tanks, I breath nitrox. Yes, I know air is a form of nitrox, but I'm ignoring that fact for the sake of discussion. Lee >rental or somebody else's tanks, I breath nitrox. Yes, I know air is a form >of nitrox, but I'm ignoring that fact for the sake of discussion. You took my response too seriously, but you did get it. :) --- Rich http://richlockyer.tripod.com/ > >rental or somebody else's tanks, I breath nitrox. Yes, I know air is a form > >of nitrox, but I'm ignoring that fact for the sake of discussion. > > You took my response too seriously, but you did get it. :) One of my less attractive characteristics is taking things too seriously. That one is followed by seeming to be too serious in my responses. I need smileys. 8^) Lee > > >rental or somebody else's tanks, I breath nitrox. Yes, I know air is a > form [quoted text clipped - 5 lines] > That one is followed by seeming to be too serious in my responses. I need > smileys. 8^) C'mon Lee, leave the excuse of dryness to those of us that really need it. Dave. > > >rental or somebody else's tanks, I breath nitrox. Yes, I know air is a > > >form of nitrox, but I'm ignoring that fact for the sake of discussion. [quoted text clipped - 4 lines] > > Lee But that pales in comparison to Lee's unattractive characteristic of picking on fights with others on subjects on which he knows little or nothing about -- such as dive physics or dive physiology, and dive computers! In one such recent episode, his characteristic style of "argument through obfuscation" inspired a rec.scuba celebrity trivia quiz: http://makeashorterlink.com/?R20043438 On the present subject: Do any nitrox computers measure gas mix Lee's sole knowledge seems to be his play on his confusion between "nitrox" and "EAN", and neglected the fact that the subject was asking if nitrox <EAN> computers "measure" gas mix. The answer should be "negative". The USER of the commonly used EAN dive computers manually sets the approximate O2 level in the nitrogen-oxygen mix; the EAN computer does not "measure" the gas mix. ;-) Uwatec Aladin Air-X Nitrox computer might have wished it did know how to measure gas mix. > But that pales in comparison to Lee's unattractive characteristic of > picking on fights with others . . . Look who's talking. Who did you say liked to pick fights? How'd you get out of my blocked file? Don't bother answering. You'll be back where you belong before you get this. Lee >One factor keeping me from Nitrox certification is I feel the courses are a rip off. They >are $300 here for the knowledge content of a thin book. Are you still in SoCal? Go see Gordon in Laguna. I bought my card for $150 and one evening. --- Rich http://richlockyer.tripod.com/ > I just took a nitrox course and -- holy crap -- the gas mix changes as the > temperature of my tank changes? I was wondering if any of the nitrox compatible [quoted text clipped - 4 lines] > Wade Guthrie > news@adventure101.com Did they teach you in the class that the gas mix changes with temperature? Better find a new teacher! That would make diving with Nitrox extremely dangerous. I know of no computer that analyzes the gas mix - but something new might be out! > I know of no computer that analyzes the gas mix - but something new > might be out! What about VR3 ? Regards. Shrek > I just took a nitrox course and -- holy crap -- the gas mix changes as the > temperature of my tank changes? I was wondering if any of the nitrox compatible > air-integrated dive computers also acted as an oxygen analyzer (so that it can > determine, dynamically, what your PPO2 is)? Sounds like one of those GUE courses where they miscalculate gas density. Better take a course from someone that knows what they're talking about. PPO2 is a function of depth and mix (FO2). You enter the mix into any computer, the computer monitors pressure (depth) and determines, dynamically, what yer PPO2 is. Don't worry about tank temperature. There are a few computers that also sample mix, but you don't need or want them. >> I just took a nitrox course and -- holy crap -- the gas mix changes as the >> temperature of my tank changes? I was wondering if any of the nitrox compatible [quoted text clipped - 11 lines] >There are a few computers that also sample mix, but you don't need or >want them. Correct me if I'm wrong, but I thought water was "not a good thing" for oxygen sensors. Wouldn't this bode ill for a computer based sensor, no matter how well it sealed? And if it actually samples off the HP hose, how do you calibrate the thing? Just idle curiosity, I sample the old fashioned way. Signaturedillon When I was a kid, I thought the angel's name was Hark and the horse's name was Bob. The message <vegq80141c4qc8d0dc1gn4387cv9gf5c2l@4ax.com> from Dillon Pyron <dmpyronINVALID@austin.rr.com> contains these words: > Correct me if I'm wrong, but I thought water was "not a good thing" > for oxygen sensors. Wouldn't this bode ill for a computer based > sensor, no matter how well it sealed? And if it actually samples off > the HP hose, how do you calibrate the thing? > Just idle curiosity, I sample the old fashioned way. Water in general is not a good thing for O2 sensors, however in the Inspiration, the 3 sensors are in the headset of the RB, with around 100% humidity the whole dive. Occasionally on a long dive, water will oclude the face of cell2 and an error will sound, it's neve happened to me so far, but I've heard alarms sound on an odd occasion for that reason. The 4th vr3 cell is also in the loop, in the same humidity, and again no real problems happen - mostly its all 'theoretical' rather than 'actual' problems people get het up on. > I just took a nitrox course and -- holy crap -- the gas mix changes as the > temperature of my tank changes? No, pressure changes with temprature. dan@scuba-training.net http://www.scuba-training.net > > I just took a nitrox course and -- holy crap -- the gas mix changes as the > > temperature of my tank changes? > No, pressure changes with temprature. > > dan@scuba-training.net > http://www.scuba-training.net Umm, would you care to put that into context for scuba? There is this little known law known as the ideal gas law PV = nRT that usually comes into play scuba tanks which are constant volume. > > > I just took a nitrox course and -- holy crap -- the gas mix changes as > > > the [quoted text clipped - 11 lines] > > that usually comes into play scuba tanks which are constant volume. He he, universal gas law was not part of the original poster's dive class! Nor, his instructor's! ;-> PS: Before the nitpickers join in, unita and I both know that scuba cylinders are not really constant volume. I don't know what you guys are laughing about. The message you responded to seems to me to say the same thing you guys do, that pressure changes with temperature. Lee > > > > I just took a nitrox course and -- holy crap -- the gas mix changes as > > > > the [quoted text clipped - 19 lines] > PS: Before the nitpickers join in, unita and I both know that scuba > cylinders are not really constant volume. > I don't know what you guys are laughing about. The message you responded to > seems to me to say the same thing you guys do, that pressure changes with > temperature. > > Lee Right as always, Lee. My original response was concise and to the point. > > > > > I just took a nitrox course and -- holy crap -- the gas mix changes > as [quoted text clipped - 20 lines] > > PS: Before the nitpickers join in, unita and I both know that scuba > > cylinders are not really constant volume. >> PV = nRT >> >> that usually comes into play scuba tanks which are constant volume. > >He he, universal gas law was not part of the original poster's dive >class! Nor, his instructor's! Not sure that it's wise to defend oneself, here, but I thought I'd mention that the original poster did get the ideal gas law in college 20 years ago. I remembered that 'n' was a function of the material in question. Therefore, even though what the instructor said did not make intuitive sense, it wasn't a far reach to believe that 1) since Pressure is proportial to (something specific to the gas) times temperature, that 2) the pressures of the two gasses in question would react differently to temperature such that 3) the ratio of partial pressures might drift a few percent with temperature change. Since then, I've looked up the ideal gas law and convinced myself that, no, the mix won't change. But, at the time, it seemed plausible. -- Wade Guthrie news@adventure101.com > I just took a nitrox course and -- holy crap -- the gas mix changes as the > temperature of my tank changes? Well... How do you suppose that works? Do some of the N2 or O2 molecules just vanish? Does a nuclear reaction take place in your tank to convert one to another? Or was your instructor talking crap? Forget the entire course - you can't trust the source. Ask for your money back and find a decent instructor. Alun Harford > > I just took a nitrox course and -- holy crap -- the gas mix changes as the > > temperature of my tank changes? [quoted text clipped - 4 lines] > another? > Or was your instructor talking crap? At cryogenic temperatures, the Oxygen will condense out before the Nitrogen. Perhaps this is what the instructor meant :-). >>Wade Guthrie <news@adventure101.com> wrote in message > [quoted text clipped - 14 lines] > At cryogenic temperatures, the Oxygen will condense out before the > Nitrogen. Perhaps this is what the instructor meant :-). thought we were talking about diving - that seems to be out of the realms of nitrox (enriched air) diving! >>>Wade Guthrie <news@adventure101.com> wrote in message >> [quoted text clipped - 17 lines] >thought we were talking about diving - that seems to be out of the >realms of nitrox (enriched air) diving! Makes it easier to mix. One cup oxygen, two cups nitrogen, 1/4 tsp trace gases. Instant 33 Nitrox. Signaturedillon When I was a kid, I thought the angel's name was Hark and the horse's name was Bob. >I just took a nitrox course and -- holy crap -- the gas mix changes as the >temperature of my tank changes? I was wondering if any of the nitrox compatible >air-integrated dive computers also acted as an oxygen analyzer (so that it can >determine, dynamically, what your PPO2 is)? Either your class covered new and interesting data that nobody knows about yet, or your instructor is completely full of sh.t and you need to take a nitrox class from an instructor that will teach you what you need to know. The mix won't change if it is blended properly. Even if it DOES change, you could theoretically be 2% off on your calcs and still not be in a significant danger of getting bent on BT, or getting toxed on a MOD violation. The amount of oxygen available in the atmosphere changes slightly due to temperature and humidity variations, but once in the tank? No... it's not going to change. If it WERE to change, it would be toward the higher O2 level, because that's what happens in the atmosphere... hot air lowers the effective PPO2... and that would mean that when you're diving in 60 degree water with a tank that was heated to 120 by the shop monkey giving you a fast fill, you would be safer from getting bent. Just buy only EAN32 fills, buy an EAN32 table, and don't dive below 111ft unless you have to go deeper to rescue your buddy. That's all you need to know to dive nitrox. --- Rich http://richlockyer.tripod.com/ > The mix won't change if it is blended properly. But it will if I make a mistake at the fill station? Signature"We're going to rush the hijackers." -Jeremy Glick, aboard United Airlines flight 93, September 11, 2001 >> The mix won't change if it is blended properly. > >But it will if I make a mistake at the fill station? Ya... you have to roll the tanks around on the floor :) --- Rich http://richlockyer.tripod.com/ >> The mix won't change if it is blended properly. > >But it will if I make a mistake at the fill station? Oops... hit "send" too soon. There could be a variance if the air is slammed in causing significant heating after the O2 is put in. But you'll end up with a mix higher in O2 anyways, since you won't be putting in "enough" air... unless you plan for it and intentionally overfill the tank, and then you won't know WHAT you've got until you let the tank cool and analyze it..... ....which he should be doing ANYWAYS just before he puts hit reg on the tank. :) --- Rich http://richlockyer.tripod.com/ > The mix won't change if it is blended properly. How is "Properly" defined? use a spoon, or a paint shaker? Signaturethe most committed always win >> The mix won't change if it is blended properly. > >How is "Properly" defined? use a spoon, or a paint shaker? See my response to Jammer. O2 going in at 10psi/min Air topper going in at 500psi/min Tank heats up and reaches 3000, but you've got 34% instead of 32%. But it's still going to analyze at 34% and THAT won't change. --- Rich http://richlockyer.tripod.com/ |
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