• Welcome to ScubaBoard


  1. Welcome to ScubaBoard, the world's largest scuba diving community. Registration is not required to read the forums, but we encourage you to join. Joining has its benefits and enables you to participate in the discussions.

    Benefits of registering include

    • Ability to post and comment on topics and discussions.
    • A Free photo gallery to share your dive photos with the world.
    • You can make this box go away

    Joining is quick and easy. Login or Register now by clicking on the button

Accumulated 02 following a large number of repetitive Nitrox dives over 3 days.

Discussion in 'Advanced Scuba Discussions' started by Astran, Sep 30, 2019.

  1. Astran

    Astran Banned

    # of Dives: 200 - 499
    Location: MD
    67
    16
    8
    Yes so going forward, know that I am quite familiar with the principles of Nitrox and the CNS clock and the ramifications for absorbing too much 02 in your tissues. My thread is really about how significant a factor it was on this particular trip as compared to literally dozens more that were similar but did not cause this issue and why it may have happened on this particular trip and not the others in hundreds of EAN dives.

    if you're going to tell me that I need more training, or I should already know this, or otherwise suggest that I'm a moron for not knowing basic Nitrox principals or whatever, you won't be getting a response.
     
    KenGordon likes this.
  2. rhwestfall

    rhwestfall Solo Diver

    # of Dives: 200 - 499
    Location: "La Grande Ile"
    12,762
    11,714
    113
    I've always wondered how much and what kind of diving would be necessary for this to happen..... Never imagined it possible....

    and now I know....
     
  3. Manatee Diver

    Manatee Diver Manta Ray

    # of Dives: None - Not Certified
    Location: Tampa Bay, FL
    801
    492
    63
    If you round up you probably went over. If you went to the exact numbers you probably were on the borderline of max exposure.
     
  4. Astran

    Astran Banned

    # of Dives: 200 - 499
    Location: MD
    67
    16
    8
    Ok that's what I thought but it seemed like there was one or two posts that were specifically addressing the P02 setting on the computer. Got it.
     
  5. Astran

    Astran Banned

    # of Dives: 200 - 499
    Location: MD
    67
    16
    8
    My computer might disagree with you, at least for the 20 remaining minutes of that dive which was flashing a full 02 bar and zero DTR.
     
  6. JackD342

    JackD342 Dive Shop

    # of Dives: 500 - 999
    Location: Highland Park, IL
    2,370
    1,393
    113
    Really? OP said at least 3 different computers across two divers all ran out of time, and they kept on diving. That is the very definition of "go over" the limit.
     
  7. rjack321

    rjack321 Captain

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, WA
    9,134
    3,041
    113
    I'm guessing the oceanic ran up against the CNS limits as @tbone1004 posted since the surface intervals were short and the PPo2s were high.

    Pulmonary limits are usually more permissive / less controlling until you get up into the 8-12hrs exposure range.
    See figures 1 and 2
    https://www.shearwater.com/wp-content/uploads/2012/08/Oxygen_Toxicity_Calculations.pdf

    or here they are on the same graph but hard to read
    Oxygen Toxicity - Signs and Symptoms | Dive Rite

    Both forms of toxicity should have been covered in your nitrox course @Astran
     
    arthurng311 likes this.
  8. Manatee Diver

    Manatee Diver Manta Ray

    # of Dives: None - Not Certified
    Location: Tampa Bay, FL
    801
    492
    63
    Using the NOAA charts I came up around 90% for the first day. And 112% for the second day, but I am rounding up. I have no idea about the third day because we don't have times.
     
    Subcooled and rjack321 like this.
  9. Subcooled

    Subcooled Assistant Instructor

    # of Dives: 200 - 499
    Location: Finland
    995
    255
    63
    Ignoring warnings is dangerous. The odds are small that you are that superhuman who can take more abuse than others.

    If the dive computer says no, it's a no.
    Period.
     
  10. kmarks

    kmarks Divemaster

    # of Dives: 100 - 199
    Location:
    361
    270
    63
    It wasn't meant to be accusatory, just curious. I don't know anything about the other agencies, but I can just about quote it from the SSI EANx manuals for you.
    You came here looking for an answer to a question and you got several thorough, well-thought answers. Nobody has called you a moron, or said anything disparaging, only suggested that if you are unfamiliar with a key concept of the EANx training, you may want to review or take a refresher on it.
     
    arthurng311, markmud, Ikthus and 2 others like this.

Share This Page