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What to do when a DH reg free flows underwater?

Discussion in 'Vintage Diving & Equipment' started by RecklessAmateur, Oct 27, 2020.

  1. RecklessAmateur

    RecklessAmateur Angel Fish

    # of Dives: 500 - 999
    Location: Philadelphia, PA USA
    Relatively new but enthusiastic DH diver here (Phoenix RAM). My question is about when/if a DH regulator freeflows. Can you still breathe it? If not, and you breathe from your octo, how do you prevent the freeflowing reg from emptying out your tank pronto?
  2. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
    best way is to put a DSV on there... @Luis H did a great job designing it

    Store | Vintage Double Hose

    Otherwise you just have to keep the mouthpiece below the diaphragm to prevent it and hopefully stop it from freeflowing. You can breathe it while it's freeflowing, no different than a normal second stage
    Bob DBF likes this.
  3. Luis H

    Luis H Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Maine
    Yes, you can breath out of a free-flowing double hose, but I have to ask why is it free-flowing? If it is that you just took the mouthpiece out of you mouth, then that is normal and it will stop free-flowing when you put it back in your mouth (the use of a DSV would stop it from free-flowing when it is out of your mouth).

    If it is free-flowing when it is in your mouth... then you need to service it... you have a leak. It could just be a bit of tuning or it may indeed need some new seats or other malfunction.

    Have fun diving it.
    couv, axxel57 and John C. Ratliff like this.
  4. jvanostrand

    jvanostrand Nassau Grouper

    # of Dives: 1,000 - 2,499
    Location: Waterloo, Ontario, Canada
    I was taught to breathe a free-flowing reg. Why waste the air? A DH reg will always free flow if the mouthpiece is above the diaphragm.
    Bob DBF and John C. Ratliff like this.
  5. John C. Ratliff

    John C. Ratliff Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Beaverton, Oregon
    That's actually a way taught in days of old to clear the mouthpiece of water, to bring the mouthpiece above the regulator to initiate a freeflow, then put it into your mouth and blow out (to blow out any water still there, left side down), then breath normally. The DSV mouthpiece is great, and I have one, but you can easily dive a double hose without it; it's very convenient if you want to swim on your back.

    The double hose regulator won't always freeflow if the mouthpiece is above the regulator, only if the mouthpiece is out of your mouth and above the low pressure diaphragm of the regulator.

    axxel57 likes this.
  6. RecklessAmateur

    RecklessAmateur Angel Fish

    # of Dives: 500 - 999
    Location: Philadelphia, PA USA
    Hey thanks for the reply. I actually have a DSV mouthpiece, and I understand why a DH reg freeflows normally. Just more interested in what happens if it freeflows by accident. (Apologize for my relative lack of understanding of how the reg actually works!:))
  7. Scuba Lawyer

    Scuba Lawyer Manta Ray

    # of Dives: 5,000 - ∞
    Location: Laguna Beach, California
    Not sure if this is what you are asking, but if you lose your mouthpiece the freeflowing DH will rise up above your head. Lean back your torso so it is parallel with the surface and you are looking at the surface, then just reach up to recover the mouthpiece. My 2psi
    dead dog likes this.
  8. lexvil

    lexvil ScubaBoard Sponsor ScubaBoard Sponsor

    # of Dives: 1,000 - 2,499
    Location: jamestown, ca.
    If you are asking a “what if it freeflows while I’m breathing from it” due to a mechanical failure internally? Your dive is over, head to the surface ASAP! You can breath off of it but the air will not stop flowing.
  9. GJC

    GJC Solo Diver

    # of Dives: 200 - 499
    Location: Southern California, USA
    If you are talking about a major mechanical failure (blown first stage seat or second stage stuck full open) there is nothing you can do to stop it except shutting off the tank valve. You can breath from the mouthpiece while it free flows just like you can from a single hose free flow, but a fully open second stage will drain a full tank in just a few minutes so you don't have a lot of time to think about things and you need to surface ASAP or find your buddy and use his octo.

    If you can't get to your buddy and you are deep, you might be able to feather your tank valve if you can reach it easily (open it for inhale, close it while exhaling) to make it last a little longer. This takes some skill to do and can distract you from remembering to do other things like venting your BCD on the way to the surface.

    I mostly dive solo and don't trust instabuddies to be that helpful in an emergency if I have to be paired with one, so I always dive with a pony.

    Not that long ago I started my ascent on a dive using my DA Aquamaster and when I looked up I saw a lot of bubbles. Not a full open free flow, but more than a little tank valve o ring leak. Back at home I opened the can and found salt crystals inside. The old rubber diaphragm was too stiff and lacked the pliability to get a good seal, allowing sea water into the can. The crystals got stuck in the second stage seat causing the leak/partial free flow. It was probably leaking most of the dive but I hadn't heard the bubbling and my tank pressure hadn't dropped fast enough during the dive for me to notice the leak. The old rubber diaphragm has been replaced with a new silicone one. I hope the silicone one lasts as long as the 60 year old rubber one did.
    RecklessAmateur likes this.

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