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Redundancy with PRAM Double Hose Reg

Discussion in 'Solo Divers' started by rx7diver, Oct 6, 2015.

  1. John C. Ratliff

    John C. Ratliff Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Beaverton, Oregon
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    Rx7diver,

    You may want to reconsider that Y-valve configuration for cold water. Your Scubapro first stage is not environmentally sealed, and therefore subject to cold freeze-up. Your PRAM (Phoenix Royal Aquamaster, for those who don't know about double hose regulators) has a first stage that is virtually immune to freeze-up, as it never sees water. By using this combination with the Y-valve, you are actually compromising the system's safety. This is because you have introduced a more failure-prone component into this system, and the system as a whole is only as good as the most failure-prone component of the system. Also, you had unused LP outlets on the Phoenix first stage.

    SeaRat
     
  2. rx7diver

    rx7diver Solo Diver

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    SeaRat,

    Yes, since my Poseidon wouldn't fit (which is why I used my Scubapro, instead), in the end this experiment was more fun than practical. But, "fun" can be, um, fun!

    I suppose I could "environmentalize" my Scubapro. However, this would decrease the "fun" quotient.

    Safe Diving,

    rx7diver
     
    John C. Ratliff likes this.
  3. John C. Ratliff

    John C. Ratliff Instructor, Scuba

    # of Dives: I'm a Fish!
    Location: Beaverton, Oregon
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    I hear you concerning the "fun" aspect. I have done a lot of experimenting with double hose regulators, and usually dive them on my twin 45s with a Sherwood double post manifold.

    [​IMG]

    [​IMG]

    That way I can div the double have with good redundancy, and have my octopus, power inflator, and dive computer.

    SeaRat
     
    rx7diver likes this.
  4. DA Aquamaster

    DA Aquamaster Directional Toast ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: NC
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    As I recall, they used back mount harness for the DAAM when used with a hookah. The same concept would work for side mount, with the tanks feeding a manifold that in turn feeds the hookah port.

    Chest mounting wouldn't work as the second stage diaphragm would be too low and would be force feeding you air.

    ----

    However, I dive a side mount rebreather (KISS Sidekick) and the work of breathing is quite good with the counter lung mounted right on my centerline. The same would apply to a side mounted double his regulator. Provided it is truly side mounted (and not "low mounted" like a stage) and is in line with the center of your lungs, it should breath very well. You'd just need to have hoses that would allow the mouthpiece to be routed to your mouth comfortably like a side mount rebreather.
     
  5. DA Aquamaster

    DA Aquamaster Directional Toast ScubaBoard Supporter

    # of Dives: 2,500 - 4,999
    Location: NC
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    I agree. People don't understand that on a double hose regulator like the DAAM, PRAM, etc both the first stage and the second stage are environmentally sealed. Even with a bad mushroom valve, you really have to work at it to flood the second stage, and you'd need a very large ball of ice around the can before it would start to interfere with the diaphragm so freeze ups in a double hose reg are almost always an artifact of water in the air supply, which won't happen on a properly maintained compressor and filter stack.

    ----

    Y valves are better than H valves as there are far fewer connections and o-rings to fail, but if you don't need one, it's just useless excess baggage and something else that can fail.

    In the case of a double hose reg, and a Y valve for redundancy, the Y valve won't prevent gas loss from a failed burst disc or neck o-ring, nor will it solve an out of gas scenario. All it will do is provide a second regulator, and in this case, particularly in cold water, you're adding substantially more risk of a freeze flow by adding a second single hose regulator to the system.

    A modern double hose design like the PRAM, with it's modern first stage design (basically Aqualung Titan guts) and modern hoses, mouthpiece or DSV, diaphragms, mushroom valves, and HPR second stage is a very, very reliable design, and in cold water it is much more reliable than any single hose regulator.
     
    John C. Ratliff and rx7diver like this.

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