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The Venturi switch

Discussion in 'Dive Equipment' started by Steppenwolf, Feb 28, 2008.

  1. Steppenwolf

    Steppenwolf Well-Known Member

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    I understood that the Venturi switch on the second stage of the regulator should be in the "-" position for the entry to minimise risk of freeflow, after which it is ideally changed to "+" during the dive itself. I try to remember this for most dives, but there have been occasions when I've forgotten and not noticed much difference during the dive. Any views or comments from personal experience on this?
     
  2. Air-Guzzler

    Air-Guzzler Cannot spel and I cannut delet your post :-)

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    I used to switch my scubapro back and forwards but never had a problem.
     
  3. Steppenwolf

    Steppenwolf Well-Known Member

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    I never had a problem with my Apeks as such, but as I said have forgotten to change to "+" while diving so that the switch has remained in the "-" position all the time. However, I don't seem to have experienced any discomfort or even noticed a difference while diving and it was only on returning to the surface and customary checking that it became apparent.
     
  4. Bobco

    Bobco Active Member

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    You would in very cold water, I tend to keep mine in - for most of the dive, in + they will freeflow if given enough of a chance, say like filling a DSMB
     
  5. Sakara Drinker

    Sakara Drinker Posting Sh*te since 2005

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    However in warm water it doesn't make a blind bit of notice. Mine is wherever it was last knocked to.
     
  6. Bobco

    Bobco Active Member

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    Dont see much cold water now do you Phil:tongue:
     
  7. Sakara Drinker

    Sakara Drinker Posting Sh*te since 2005

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    Not if I can help it Bob :)
     
  8. Dougalsdad01

    Dougalsdad01 Active Member

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    With good quality reg's I was told that you will probably never notice a difference, unless you are at the limits of depth and breathing heavily after exertion.
     
  9. Ian

    Ian New Member

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    I very occasionally get freeflows at the surface if I leave the switch on (+), and I do notice underwater that the reg is harder work if I left it on (-) and I'm working hard. Not so much in warm water if I'm relaxed though...
     
  10. miniman

    miniman Member

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    Bit of a rudundent question to be honest. If YOU notice no difference why does it matter what anyone else thinks. If you can feel no difference when diving on the - position keep it there. Sorry not trying to be funny.
     
  11. Ian

    Ian New Member

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    That is a bloomin good point!!!!!
     
  12. rainbowannie

    rainbowannie New Member

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    Mine is always in the (-) position.
     
  13. Steppenwolf

    Steppenwolf Well-Known Member

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    The only reason I asked was that I overheard someone harping about freeflow risks and something like that and wanted to be sure that I was doing the right thing. After all, with something like freeflow, one does not notice anything until it actually happens. These forums are supposed to be meant for discussion and I cannot see any reason why YOU should get your knickers in a twist just because I asked the question.
     
  14. miniman

    miniman Member

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    Maybe because I'm an arsey bastard or maybe because if you know that the reg is more prone to freeflow on the + setting and you enter the water with it on the - setting and then continue the dive in the - setting with no difference to the breathe, it makes your question completly redundent.
    As I said I am not being trying to be funny (you will know if I am) as I normally find all your posts to be both informative and useful. Regards Mini
     
  15. Badknees

    Badknees Meg Pilot (retired) and Forum KGB

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    LOL the only real time it will become a free flow risk is when entering the water suddenly, thats about it, in very cold water you might have a higher sac rate which in it's self could cause a free flow.

    The rule of thumb "-" when entering "+" when diving as it states in the instructions.
     
  16. sazza

    sazza New Member

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    lord knows never bother moving mine it breaths ok so i leave it alone......

    only time i ever had a free flow was in the car park the other week when it actually was freezing totally forgot and did my usuall breath in to check everything was working and air on.......DOH!!!!!!! when sira and i got inot the water that day everything was fine.........
     
  17. gunner

    gunner Member

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    Thats the only time I have noticed it. One of my first times at 40 odd metres, struggling to get a full lung full of air, and finally noticing the venturi inthe "-" position. Pushed to "+" - loads of lovely air.

    At shallow depths it makes no noticable difference.
     
  18. Jenkins

    Jenkins Friends, Romans, countrymen, lend me your ears.

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    My old regs didn't have any adjustment and were quite a high resistance breathe, so after 200+ dives that is what I am used to. That said bellow 30m you did have to "pull" the air through, infact that and the fact they were A-clamp is why I upgraded.

    My mew ones are Apeks XTX200, the silver screw is fully out and the "+/-" is always set to the high resistance (as I prefer the heavier breathe), but if I go below 30m they get noticably harder and at that point yes I make it easier.
     

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