• 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

Effect of gas density while deep diving

Discussion in 'Technical Diving Specialties' started by Kfay, Oct 17, 2019.

  1. rjack321

    rjack321 Captain

    # of Dives: 1,000 - 2,499
    Location: Port Orchard, WA
    8,973
    2,828
    113
    But but but Rich Pyle!
    so basically you are ignoring science, got it!
     
    BenjaminF likes this.
  2. Kfay

    Kfay Angel Fish

    # of Dives: 200 - 499
    Location: Florida
    63
    5
    8
    I have read this and it is very interesting however... Newer data shows many different safety concerns and this experiment does not say anything about co2 retention with gas density. Regardless the testing is pretty incredible and makes me think there is much more testing to be done. Thanks for sharing, I will not be considering any data from this experiment in my diving though. :wink:
     
    АлександрД likes this.
  3. Kay Dee

    Kay Dee Barracuda

    # of Dives: I'm a Fish!
    Location: Here, there, and everywhere
    267
    179
    43
    Anyone who thinks they already have a gas density / work of breathing issue when diving OC air at or about 40m needs to buy themselves a better regulator!

    Edit: It also should be noted that there is a difference between 'deep stops' and so-called 'Pyle stops' (as far as the deco profile goes), but many people seem to think they are one and the same. Not advocating for or against them, just want to 'register' the fact that there is a difference and the two should not be considered one and the same deco profile.
     
  4. fsardone

    fsardone Solo Diver ScubaBoard Supporter

    # of Dives: I just don't log dives
    Location: Rome, Italy
    463
    434
    63
    You are an arsonist!
    The issue is not the deep stop, is the aidea that stopping deep would shorten the shallow deco time .... this is really arson :)
    :popcorn:

    Back on topic .... While on OC the only work you do is keep the 2nd stage walve open by creating a slight depression in the regulator. On CCR you need to keep all of the gas in the loop moving through the scrubber. It really makes a difference. Try to switch from diluent air to heliair at 40 meters. And you will have a revelating moment. Both for density and narcosis.
     
    RayfromTX likes this.
  5. Kay Dee

    Kay Dee Barracuda

    # of Dives: I'm a Fish!
    Location: Here, there, and everywhere
    267
    179
    43
    And there, as they say, lies the rub. Comparitively speaking, for the same gas (in this case air shall we say) the WOB is greater the deeper you go on a CCR as you are doing the work (or the W in WOB) as opposed to a mechanical assist - as it were - on OC almost 'forcing' the air into your mouth.

    Hence why I would dive OC air deeper than CCR air (if I had too, which I don't).:facepalm:
     
    FreeFlyFreak and RayfromTX like this.
  6. fsardone

    fsardone Solo Diver ScubaBoard Supporter

    # of Dives: I just don't log dives
    Location: Rome, Italy
    463
    434
    63
    Concur
     
  7. Lorenzoid

    Lorenzoid idling in neutral buoyancy

    # of Dives: 500 - 999
    Location: Atlanta, USA
    8,977
    5,468
    113
    Or more likely, needs to get their regulator tuned. It's my understanding that at that modest depth WOB doesn't vary among (properly tuned) regulators enough to be noticeable to most people.
     
    100days-a-year likes this.
  8. 100days-a-year

    100days-a-year Solo Diver

    # of Dives: 5,000 - ∞
    Location: NE Florida
    2,097
    483
    83
    Haven't noticed any WOB issues on deep air or lean nitrox diving my Tabata regs. I feel more resistance in thicker wetsuits shallow.
    There is a threshold I'm sure where WOB, CO2 retention and narcosis become an issue due to gas density but IME it's subjective.
    I also reiterate that some folks are impaired @ PPN .79 and adding any diving or other task loading only compounds it.
     
    FreeFlyFreak likes this.
  9. rsingler

    rsingler Scuba Instructor, Tinkerer in Brass Staff Member ScubaBoard Sponsor

    # of Dives: 500 - 999
    Location: Napa, California
    3,196
    3,493
    113
    But if you are part of the population (10-30%) that does not automatically hyperventilate in response to elevated CO2, then you lose the trigger that alerts you to a CO2 hit before it's too late.

    Perhaps there will eventually be a medical screen made available to divers that want to start Tec, to alert them that they're part of this population-at-risk. It would be an easy enough clinic to set up. Haven't thought about how many divers you'd have to see at what price to make it work financially, tho...
     
    100days-a-year and Fibonacci like this.
  10. 100days-a-year

    100days-a-year Solo Diver

    # of Dives: 5,000 - ∞
    Location: NE Florida
    2,097
    483
    83
    Exactly, there are too many variables between divers physical condition, locations, gears etc..for me to accept a blanket limit that is shallower than many thousands if not some millions of dives have been safely completed to.
     

Share This Page