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Discussion in 'Advanced Scuba Discussions' started by DC53, Nov 7, 2011.

  1. Mossman

    Mossman Solo Diver

    # of Dives: 500 - 999
    Location: SoCal
    ANDI recommends 1.45, or at least it used to. That's a little closer.

    The 1.4 is rather arbitrary, just as PADI's 60' maximum depth for open water divers is rather arbitrary.

    And what other training agencies are you aware of? I just checked my TDI "A Diver's Guide to Advanced Nitrox Diving" (2001 rev 2) and found the following:

    "Typically we will use 1.6 ATA for any 'maximum' exposures of oxygen, although some divers may reduce that depending on the diving conditions. . . . Remember back to your Nitrox course, it is YOU who determines what oxygen exposure you want for the dive. In many cases, this will be the 1.6 ATA as previously indicated, however, some divers choose 1.5 ATA or even 1.4 ATA as the maximum value for their particular dive." (p. 18)

    "At an oxygen exposure of 1.6 ATA, the diver is limited to a 45-minute single exposure." (p. 35)

    There are far more liberal guides out there, to be sure. In Weinke's Technical Diving in Depth, for instance, Table 7 on p. 92 gives the Oxygen Exception Exposure Time Limits, showing a 75 min single exposure limit for 1.6. It also gives 75 min at 1.7, 60 min at 1.8, 45 min at 1.9, and 30 min at 2.0. The latter used to be considered the standard MOD until we got too dang conservative and started using 1.6. Now it's 1.4. By tomorrow it will probably be 1.0, with really conservative folks telling you to not use nitrox below the surface or you'll certainly die. And then we'll have come full circle.
  2. beautybelow

    beautybelow Captain

    # of Dives:
    Location: Naples, Florida
    I learned 1.6. I teach 1.4 with a contingency level of 1.6.

    To say that the difference between 1.4 and 1.47 is even an issue in diving a tank of ean 30 I think is a bit of over-analyzing.
  3. Rainer

    Rainer DIR Practitioner

    GUE is 1.4 max, 1.2 average on shallow dives; 1.0 (or lower...) for deep stuff. We're a bunch of pu$$ies, though (and don't mind a bit of extra deco vs. the tox risk and less efficient deco). :)
  4. SeaCobra

    SeaCobra Dive Shop

    # of Dives: 2,500 - 4,999
    Location: West Chester, PA
    NAUI is 1.4 with 1.6 for contingencies. Gotta draw the line somewhere and based on this question, not sure how I am the one over analyzing.
  5. Mossman

    Mossman Solo Diver

    # of Dives: 500 - 999
    Location: SoCal
    Drawing the line somewhere is one thing, implying that the diver had more important issues to worry about besides an octopus squeezing his carotid artery simply because he barely exceeded 1.4 for 15 min isn't overanalyzing, it's just dead wrong.
    Rainer likes this.
  6. dtdiver

    dtdiver Solo Diver

    # of Dives: 500 - 999
    Location: rochester ny
    You have about 20 secs without blood flow to brain before lights out.
  7. gypsyjim

    gypsyjim I have an alibi ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: capital region of New York
    About enough time to reach for your knife, if you don't stop to do a lot of math first.

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