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Single first stage on twinset?

Discussion in 'Technical Diving Specialties' started by Markos Valsamis, Feb 11, 2020.

  1. Markos Valsamis

    Markos Valsamis Angel Fish

    # of Dives: 100 - 199
    Location: Athens
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    Is it ok to dive with a twin-set where only one first stage is used? (With the manifold open and the unused cylinder valve shut)? (effectively making the twinset a single larger cylinder with more failure points !)

    Reason for asking is that I only have two first stages and want to know if I can give one to my buddy for some dives (who uses a single cylinder).
     
  2. runsongas

    runsongas Great White

    # of Dives: 500 - 999
    Location: California - Bay Area
    3,701
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    hose lengths will be off and you lose redundancy, but technically yes. your buddy should just get their own regulator.
     
    fish149 likes this.
  3. Markos Valsamis

    Markos Valsamis Angel Fish

    # of Dives: 100 - 199
    Location: Athens
    13
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    Yes it definitely doesn't make sense, just wondering if it's possible- mainly whether it's fine to have a cylinder with a closed valve without a first stage attached to it.
     
  4. rhwestfall

    rhwestfall Solo Diver

    # of Dives: 200 - 499
    Location: "La Grande Ile"
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    I'd likely want to plug the other valve if I was going to dive like that (which I wouldn't). I'd probably close the isolator too, diving one tank at a time... (but again, I wouldn't do it)

    YMMV
     
  5. PfcAJ

    PfcAJ Orca

    # of Dives: 5,000 - ∞
    Location: St Petersburg, Fl
    7,598
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    Regs aren’t that expensive...

    Nickel rocketry
     
  6. rddvet

    rddvet DIR Practitioner

    # of Dives: 50 - 99
    Location: Florida
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    Sure you can do it, but not to be a douche, if you’re asking the question why are you even diving doubles? The point of doubles is redundancy and increased gas capacity. You’re taking away one of the 2 reasons to dive doubles. You’re buddy can find a g250 and mk10 combo on ebay for less than $150. Thats a much better solution.
     
    fish149 and rongoodman like this.
  7. guruboy

    guruboy Divemaster ScubaBoard Supporter

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    This.

    How do you not know the answer if you are diving doubles?
     
  8. ofg-1

    ofg-1 Course Director

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    Well, this guy only did it for 50 years, but what does he know.


    hqdefault.jpg
     
    BlueTrin, Fibonacci, Bob DBF and 3 others like this.
  9. kensuf

    kensuf Cave Instructor

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    Never leave a valve without a reg on it.
     
  10. kensuf

    kensuf Cave Instructor

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    That was a single reg manifold. Different beast.
     

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