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Thread: Nitrox...the gateway gas.

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    Shearwater Copis Diver Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy's Avatar
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    Nitrox...the gateway gas.

    Ok, after all these years of diving open circuit and shying away from the hastle and expense of diving nitrox...and after becoming very interested in eCCR's my wife and I finally got our basic nitrox cirtification this weekend. My wife has been quite hesitent to get into rebreathers because of the expense and bulk and complexity of gear. Taking the Nitrox class together has made the advantages of a rebreather much more vividly clear to both of us...and thus we are more likely to rationalize the expense and time investment (and ofcourse, it's a pre-rec for CCR).
    If there is anyone reading this blog who is like me(or should i say, like i was), interested in rebreathers without nitrox experience but not fully convinced (or who has a wife/dive partner that is scowling at the cost) that rebreathers are the way to go then i suggest taking a nitrox course before going any further...the advantages of nitrox become very clear in the course, and so do it's limitation. As the value of Nitrox became more vivid during the course, even more so did the value of continuous gas blending on the fly to optimize the ratio of O2 and N at each depth to optimize maximum nitrogen displacement and reduce the limits set by O2 toxicity/MOD, as is done by a rebreather. Very quickly nitrox seemed like a rather arcane way of displacing nitrogen, the fixed ratio has significant draw backs like: You can't take advantage of the fact that all the way down to your max depth you can only be breathing a much leaner mix than those shallower depths would allow and What if you want to go deeper than you planned...donditions are better than expected, you see something you want to explore below the MOD...oops, can't do it on nitrox! You've had to choose a specific mix of O2 (the lowest common denominator) based on your maximum planned depth). Or lets say your in a down welling that suddenly picks up and you go below the MOD without choice and your huffing against strong current, or for any reason end up below your MOD?...could be end of story on Nitrox!
    Not to say that nitrox isn't worth it... it's more like the advantages seem to be ten fold on a rebreather. And that fill of nitrox goes up mostly in bubbles with each breath, only a small fraction of it's oxygen ever being utilized.
    for us, it's pretty likely that fixed ratio Nitrox will be our gas of choice for only a short time...as a gateway to rebreather diving.
    Last edited by Gill Envy; 2nd January 2006 at 23:52.

    Gill Envy

  2. #2
    Administrator ROB DAVIE has a spectacular aura about ROB DAVIE has a spectacular aura about ROB DAVIE has a spectacular aura about ROB DAVIE has a spectacular aura about ROB DAVIE has a spectacular aura about ROB DAVIE has a spectacular aura about ROB DAVIE's Avatar
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    Re: Nitrox...the gateway gas.

    All right, nice post! :D

    Rob

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    Kevin Hagerich Helium_diver is an unknown quantity at this point Helium_diver's Avatar
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    Re: Nitrox...the gateway gas.

    Excellent post my friend. The Dark Side now has you firmly in its grasp:D
    Helium_diver
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    Brent - Narked at 90
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    Deep Pursuit or a Camelion

    and 11 others inc. a UT-240

    Re: Nitrox...the gateway gas.

    Quote Originally Posted by Gillenvy
    .....(sic) What if you want to go deeper than you planned...conditions are better than expected, you see something you want to explore below the MOD...oops, can't do it on nitrox! You've had to choose a specific mix of O2 (the lowest common denominator) based on your maximum planned depth). Or lets say your in a down welling that suddenly picks up and you go below the MOD without choice and your huffing against strong current, or for any reason end up below your MOD?...could be end of story on Nitrox!
    ................
    Not exactly accurate, there are exposure limits based upon your uptake of O2 and the partial pressure that you are subjected to.
    Example, 1.6bar O2 has a NOAA exposure limit defined as 45 mins. 1.3bar PPO2 is 180mins etc.

    Over simplified explanation, I know.
    Good thread here -> http://www.yorkshire-divers.co.uk/fo...ad.php?t=10361

    Extrapolate..........

    Brent.
    Last edited by divetheworld; 3rd January 2006 at 06:55.
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    Re: Nitrox...the gateway gas.

    Great post, and now you understand what all the hype is all about. It is really neat to see it all come together at one time and that is what CCR diving is all about. Welcome to the path that leads to the dark side.

    Sincerely,

  6. #6
    Shearwater Copis Diver Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy's Avatar
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    Re: Nitrox...the gateway gas.

    Point taken, i didn't really address overall O2 exposure limits, focussed mostly on MOD...and also I was going to clarify a few things once i got to work but for some silly reason the edit time is now only twenty minutes from the time of first posting, after that your locked out ;~( FYI.

    Quote Originally Posted by divetheworld
    Not exactly accurate, there are exposure limits based upon your uptake of O2 and the partial pressure that you are subjected to.
    Example, 1.6bar O2 has a NOAA exposure limit defined as 45 mins. 1.3bar PPO2 is 180mins etc.

    Over simplified explanation, I know.
    Good thread here -> http://www.yorkshire-divers.co.uk/fo...ad.php?t=10361

    Extrapolate..........

    Brent.

    Gill Envy

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    Shearwater Copis Diver Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy's Avatar
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    Re: Nitrox...the gateway gas.

    oh, and i didn't really address the per hour cost of nitrox...at $9-12 a fill and 30-50min average per dive it equals or exceeds the per hour cost of diving at least some rebreathers.

    Gill Envy

  8. #8
    RBW Member Tony_Q is a name known to all Tony_Q is a name known to all Tony_Q is a name known to all Tony_Q is a name known to all Tony_Q is a name known to all Tony_Q is a name known to all Tony_Q is a name known to all Tony_Q is a name known to all Tony_Q is a name known to all Tony_Q is a name known to all Tony_Q is a name known to all Tony_Q's Avatar
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    Re: Nitrox...the gateway gas.

    Hi Gill,

    Good post.

    Your thinking on the benefits of Nitrox, impact of MOD on flexibility for planning dives to different depths is one of the reasons I am planning to move to CCR. I mainly do Club-based diving off private boats. Changing weather and differing experience/skills levels of divers on the day mean that the dives can be anywhere from 12 or 18m shallow reefs to 40m wreck dives so it can get very hard to optimise the Nitrox F02 for a dive.

    Use of Normoxic Trimix would alleviate the MOD problem for the depths I dive, but would be a very expensive option on OC here in Australia.

    It is probably another 12-18 months before the current crop of eCCRs (MEG, O2ptima, Prism or Vision which are the ones of most interest to me) have settled in the marketplace sufficiently for me to commit my hard-earned dollars.

    Happy diving
    Tony

  9. #9
    Shearwater Copis Diver Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy has a reputation beyond repute Gill Envy's Avatar
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    Re: Nitrox...the gateway gas.

    Quote Originally Posted by Tony_Q
    It is probably another 12-18 months before the current crop of eCCRs (MEG, O2ptima, Prism or Vision which are the ones of most interest to me) have settled in the marketplace sufficiently for me to commit my hard-earned dollars.
    tony, i hear you...it does seem like we are nearing or at a new threshold in eCCR value/reliability. I go back and forth about weather to just jump in or wait a little while longer. Like with so many evolving technologies it's hard to know when to jump in for fear of a big price/value break/advancement being just around the corner and yet I aint getting any younger.
    I too am eyeing the Meg, Optima and inspiration with the vision upgrade. I have a lead on used inspirations for $4-4500 USD. i may just go with the inspo, dive it for a while as is and then later get the upgrade...it's actually the least expensive way i see to get in on a very well designed and reliable unit and there is the likelyhood that i can sell it for practically what i baught it for down the line if i decide i must have another unit.
    I really like the try out i had on the optima...and yet on the other hand i have never heard of anyone selling their Meg. It seems like all the serious tec divers around here dive Megs and rave about them...but then again this is seattle, virtually the home of the Meg.

    Gill Envy

  10. #10
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    Re: Nitrox...the gateway gas.

    Just jump in, you know you want to. Those used Inspirations sound perfect for what you want to do---go for it!!!!! Just take a to your old gear and then you will have to take care of your problem.

    Welcome to the dark side, you are almost there.

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