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DIN connection leak after 'out of air' simulation

Discussion in 'Advanced Scuba Discussions' started by Markos Valsamis, Sep 19, 2019.

  1. Markos Valsamis

    Markos Valsamis Garibaldi

    # of Dives: 50 - 99
    Location: Athens
    3
    0
    1
    On a practice pool dive I was practising turning the tank valve off, the buddy signalling out of air, then turning the air back on. When I turned my buddy's air back on, there was a very large leak of air from the DIN connection on the first stage. This was uncomplicated as I gave my buddy my octopus, end of story.

    Question: why did the DIN connection leak? There was no problem with the o-ring as I later confirmed. It just seems that turning it off and on underwater resulted in the seal failing.
     
  2. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    15,737
    7,071
    113
    it probably got bumped during the drill while it was depressurized and unscrewed itself. Doesn't take much to get it to leak
     
    BlueTrin and Markos Valsamis like this.
  3. Markos Valsamis

    Markos Valsamis Garibaldi

    # of Dives: 50 - 99
    Location: Athens
    3
    0
    1
    Thanks, makes sense. I guess it is much easier to unscrew when not under pressure! Would it be reasonable to conclude that water may have got into the first stage in that instance?
     
  4. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    15,737
    7,071
    113
    yes, but if it was in a pool and you've already used it, the first stage is clean. Only thing that would be bad is if anything got into the SPG, but it's unlikely that much water got in there. When practicing OOA, I wouldn't shut the tank off and breathe it down though
     
  5. fmerkel

    fmerkel Loggerhead Turtle

    # of Dives: 1,000 - 2,499
    Location: Salish Sea (Seattle)
    1,634
    607
    113
    Be aware that the DIN can leak from the tank connection (most likely), but also from the reg itself. If the other end was loosened, maybe by someone torquing the entire reg to get the DIN unscrewed from the tank (this happens), it can loosen there also. It's essentially a bolt with threads on both ends-one to the tank, one to the reg body.
     
    drainaps, Johanan, dberry and 2 others like this.
  6. stretchthepenn

    stretchthepenn Nassau Grouper

    # of Dives: 200 - 499
    Location: Atlanta, GA
    194
    114
    43
    This same thing happened to me on an out-of-air drill. Combined with the crappy day I was already having, the experience was thoroughly unnerving.

    As said above, it sounds like the DIN post came unscrewed from its fitting into the 1st stage body. There's supposed to be a specific torque setting for re-screwing the thing into place, but in practical terms, tightening it down firmly (but not super-tightly) with an Allen wrench will fix the problem.
     
  7. dberry

    dberry Hydrophilic ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: Philadelphia
    989
    516
    93
    The same thing happened to me in Cozumel this summer. Open tank, hissing from the 1st stage. The DIN post was loose into the body, and trying to tighten it without a wrench was fruitless. It was loose enough that a small o-ring got extruded (or distorted) while still on the boat. I had a spare o-ring, and an Allen wrench to tighten it, end of story.
     

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