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J Valve

Discussion in 'Vintage Equipment Diving' started by 2Bobbyo, Apr 11, 2020.

  1. Eric Sedletzky

    Eric Sedletzky Great White

    # of Dives: 500 - 999
    Location: Santa Rosa, CA
    J valves are great. Back when they were in regular use, people knew enough to know that you shouldn’t be at 100’ and need to pull the reserve. A trained thinking diver would have been paying attention to depth and time plus volume and starting pressure, and they would’ve been back in shallow water ending the dive when the lever needed to be pulled. When the SPG came out the saying was “Oh great, now any idiot can dive”, and it’s kind of true, people now have several trick ways of monitoring their air supply and they somehow still run out.
    Unbalanced first and second stages are also a useful warning signal when air is getting low.
  2. captain

    captain Captain

    There is no inherent reason a properly serviced and operating J valve will leak down, I have J valve tanks that keep pressure indefinitely. Besides air flows from the shutoff to the J valve and then to the regulator, if the tank valve is closed the J section is not pressured.
    James79 likes this.
  3. 2airishuman

    2airishuman ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: Greater Minnesota
    The four that I have had are not like that. The J section is pressurized even when the service valve is closed.
    JamesBon92007 likes this.

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