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Free flow at 94' ffw

Discussion in 'Near Misses and Lessons Learned' started by 0321tony, Jun 20, 2019.

  1. JackD342

    JackD342 Dive Shop

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    Unless I misunderstood the original narrative, it was the alternate 2nd stage, seemingly a spontaneous event.
     
  2. happy-diver

    happy-diver Skindiver ScubaBoard Sponsor

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    If the first stage is the cause I don't want extra flow going through my primary
    when you block the secondary with one of those valves
    and the pressure has to go somewhere


    Does anyone here fold the hose in half to stop freeflow
     
    williamlee likes this.
  3. JackD342

    JackD342 Dive Shop

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    Good point and a compelling reason to think hard before putting one on BOTH 2nd stages.
     
  4. tursiops

    tursiops Marine Scientist and Master Instructor ScubaBoard Supporter

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    How would this be different than using the shutoff valve?
     
  5. 0321tony

    0321tony Angel Fish

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    It came from my alternate second stage regulator I had on a necklace around my neck. Strange thing at least for me that cought me off guard was that it was the alternate and I wasn't using it so it had no airflow going through it. For me it would have been easier to understand if it had been my primary and it froze up while in use. My primary continued to work all the way to the surface. I was half expecting that with the amount of air going through and the mid 40's water temp my first stage would freeze up but it never did.
     
  6. JackD342

    JackD342 Dive Shop

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    I wonder if you somehow accidentally compressed the purge and started a flow, then by the time you noticed and/or repositioned it had iced up. If the mouthpiece was pointing up in the water column where it was positioned, then even easier for it to happen.
     
    shoredivr and Graeme Fraser like this.
  7. stepfen

    stepfen Barracuda

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    Very well done for handling the situation and informing us about it!

    It seems it took more than 6 minutes for the tank to drain. That's my estimate based on: 3+ minutes problem solving and ascent, 2 minutes SS, 1 minute further freeflow on the surface. Can you give us a more accurate figure?

    In any way I am glad to know it is much more than the 2 minutes usually mentioned for 2nd stage/LP hose problems.

    Thanks for sharing and welcome back :)
     
  8. happy-diver

    happy-diver Skindiver ScubaBoard Sponsor

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    Right so if you didn't inadvertently operate your necklace reg then the first was stuck open or not completely closing or closing slowly with each breath, whereby your breathing did dot keep up with the amount of air your first was delivering increasing pressure in the necklace, opening the thing when the pressure became too high for the reg to remain closed.

    They are after all downstream safety valves, regs anyway

    Makes sense to me


    It's better to have a freeflow from your secondary second, than a freeflow in your mouth

    when your first stage is stuck open, utilising a shutoff increases pressure to the other reg

    Go for a dive with your finger on your primary purge

    There is no place for shut off valves in open circuit especially when
    they're available in on with the flow, and on against the flow, versions

    Does this stuff really happen or am I talking through my A

    Very good.
     
  9. chris kippax

    chris kippax Divemaster

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    Have you checked your IP?
     
  10. Gareth J

    Gareth J Manta Ray

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    Treat Flow stops with caution. If it is the second stage that as free flowed, then shutting off the flow stop would be OK. However, if it's the first stage, the second stage acts like a pressure relief valve, closing the Flow stop, would result in a burst hose.

    One other point, is it a flow restriction, even when open. Therefore it will have an adverse effect on the performance of the regulator.
     
    MinimalMayhem likes this.

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