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Venturi pre dive

Discussion in 'New Divers and Those Considering Diving' started by Undersider, Sep 20, 2020.

  1. Undersider

    Undersider Garibaldi

    # of Dives: 0 - 24
    Location: La Crosse Wi
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    Hello I am new to diving and I am wondering if someone can enlighten me about how to set a second stage before jumping in the water, my reg has a +or- with the Venturi lever, which way should this be set for “pre dive”?
     
  2. BurhanMuntasser

    BurhanMuntasser Dive Charter

    # of Dives: I'm a Fish!
    Location: Nomad
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    If the regulator second stage mouthpiece is in your mouth, the venturi should be set to the "on" position (+ or Dive). If the second stage mouthpiece is out of your mouth (on the surface for example), it should be on the "off" (- or Pre-dive) position.

    If you are in a class and going to be doing exercises where you are going to be taking the SS out of your mouth above or underwater, then it is should be on the "off" or "-" position to prevent free flow.
     
    Graeme Fraser likes this.
  3. lexvil

    lexvil ScubaBoard Sponsor ScubaBoard Sponsor

    # of Dives: 1,000 - 2,499
    Location: jamestown, ca.
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    Normally - but it would help to know what regulator.
     
  4. Undersider

    Undersider Garibaldi

    # of Dives: 0 - 24
    Location: La Crosse Wi
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    Thank you that makes sense, I have a Hog D3 with a zenith second stage
     
  5. lexvil

    lexvil ScubaBoard Sponsor ScubaBoard Sponsor

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    Location: jamestown, ca.
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  6. tbone1004

    tbone1004 Technical Instructor ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
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    your secondary should have the venturi in - and the adjustment knob all the way to -. Predive, your primary should be set the same. I usually turn mine to + for both adjustment and venturi on descent since it is pretty common to spend a few seconds at the surface, or minutes when I am teaching.
    Post dive, both regulators should have the adjustment knobs turned all the way to + to minimize spring tension and the venturi position doesn't really matter.
     
  7. rick00001967

    rick00001967 Tech Instructor

    # of Dives: 500 - 999
    Location: canada
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    i leave my second stage in pre dive all the time
     
  8. Pressurehead

    Pressurehead Angel Fish

    # of Dives: 2,500 - 4,999
    Location: Queensland Australia
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    I do the same [ Mk25 evo -s600+ 195 to -]
     
  9. poseident

    poseident Angel Fish

    # of Dives: 1,000 - 2,499
    Location: Charlotte, NC
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    You can experiment to see if it makes much of a difference for your regulator. I've not dove the HOGs, but have had regs where it made little difference what position the Dive/Pre-Dive switch was in. If that's the case, you can "set it and forget it."
    On the other hand, some regs are hyper-sensitive and you'll definitely want to ensure you are managing those accordingly. You don't ever want to make the reg "harder to breath from" on purpose. Some people have the impression that makes them use less air. "Work of Breathing" is something you always want to minimize.
     
    Jafo19D likes this.

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