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Spare Air

Discussion in 'Advanced Scuba Discussions' started by Tuytles, Oct 10, 2019.

  1. Eric Sedletzky

    Eric Sedletzky Great White

    # of Dives: 500 - 999
    Location: Santa Rosa, CA
    3,664
    3,258
    113
    I can give you some reasons why air flow could abruptly cease.
    Perhaps a tank with a lot of scale and no valve tube? The diver gets inverted and some rust or scale blocks the valve. This should have never passed a VIP.
    Another guy had an ACD that failed shut somehow. Actually happened to a diver here on SB, long drawn out thread.
    Dumpster diver had a diaphragm blow out on his first stage at depth with video running.
    A broken lever on the second stage diaphragm would also do it.

    What are the chances of any of these things happening to somebody with impeccably maintained gear and high quality brands? Nearly nil.

    99.99999% of OOA situations happen because the diver F’d up.
    No other excuse.
     
    DogDiver likes this.
  2. BRT

    BRT Giant Squid

    10,703
    6,646
    113
    I don't know the percentages. I have seen 3 OOA situations. Two of them were just stupid people who went through their air very fast because of excitement and depth without watching their SPG. One was debris in the tank suddenly shutting off flow. I know of (see around town and on the docks in Puerto Morelos) a fisherman that this happened to. Very crippled. So my experience is that it can happen.
     
  3. BRT

    BRT Giant Squid

    10,703
    6,646
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    I guess you always dive with your own tank. I like to, but often in Mexico I'm diving with someone else's tank. I don't get to inspect it before diving it. 1 in 10 million? I don't think so.
     
    dberry and wKkaY like this.
  4. Eric Sedletzky

    Eric Sedletzky Great White

    # of Dives: 500 - 999
    Location: Santa Rosa, CA
    3,664
    3,258
    113
    I hear that crap in the tank is probably the biggest reason for breathing gas to suddenly shut off.
    It’s a simple problem to minimize, just peek inside the tank once in a while and see. Whether or not dive operators around the world do this on a regular basis and keep their compressors maintained is another thing, but that problem is completely avoidable.
     
  5. Eric Sedletzky

    Eric Sedletzky Great White

    # of Dives: 500 - 999
    Location: Santa Rosa, CA
    3,664
    3,258
    113
    “If” all gear is impeccably maintained and of first rate quality.
    Crappy gear that is not maintained doesn’t count.

    What are the chances of winning the lottery? People do it all the time.
    What are the chances of top quality well maintained gear suddenly failing shut for no reason, pretty damn slim.
    1 in 10 million doesn’t sound unreasonable to me, but I can always take a 9 off or two if you think it’s better?
     
  6. johndiver999

    johndiver999 Manta Ray

    # of Dives: 500 - 999
    Location: Gainesville FL
    828
    703
    93
    A good percentage of accidents occur because mistakes are made, attention to detail was lost, inappropriate assumptions were made, reliance was placed on the wrong person or the wrong piece of equipment, misjudgments were made were made with respect to environmental conditions, a person over-estimates their skills, emotional factors or significant physical discomfort cause perceptual failings or in some motor vehicle (or diving) accidents, cognitive impairment (to some degree) was present prior to the accident.

    A redundant air supply might be useful if/when any of those factors come into play -even though most of those factors could/should be avoidable by the theoretically perfect human.
     
    wKkaY likes this.
  7. agilis

    agilis Solo Diver

    # of Dives: I just don't log dives
    Location: N.J.
    8,652
    10,277
    113
    A 6 CF bail out bottle is perfectly adequate for no decompression dives at sport diving depths.
     
  8. halocline

    halocline Solo Diver

    8,471
    2,575
    113
    I wouldn't get the nitrox spare air because it would be risky to use when completely out of air at 200ft. :D
     
  9. MaxBottomtime

    MaxBottomtime Divemaster

    # of Dives: 1,000 - 2,499
    Location: Torrance, CA
    8,744
    7,714
    113
    You don't have to be a perfect human being to avoid running out of air. Most divers never come close to running out, including some who have been diving for decades.
     
    Bob DBF likes this.
  10. Divectionist

    Divectionist Solo Diver

    # of Dives: I just don't log dives
    Location: Gold Coast, Australia
    294
    156
    43
    I rent tanks and given how sloppy and messy dive ops in a health and safety aware first world country are, I would not want to bet on the internal condition of tanks and valves anywhere in the world.

    I strongly recommend for any non-vacation diver to own their own pony bottle and carry it on every dive.

    A spare air is not sufficient for my diving, or anyone’s diving if two unfortunate events happen at once, which anyone can easily calculate. It is better than nothing, but one might as well do it right. Most of you in the US can assemble a quality pony setup for half the cost of what it is in Australia, barely making a difference to a spare air, so it is a laughable cost difference given the practical benefits.

    I think it adds immense comfort to engage in - proper - equipment redundancy practices on each and every dive.
     

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