Quarter turns

Do you back off a quarter turn?

  • Yes

    Votes: 57 46.0%
  • No

    Votes: 67 54.0%

  • Total voters
    124

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randytay

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A poll, sort of.

when you dive, do you turn on your air and then back off a quarter of a turn? Why and why not? How many of you do it because your instructor says so? If so, did he or she explain why?
 

Rick Murchison

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Poll added :)
I do back off a quarter turn.
Why? Because I've had a jammed open valve before and had to drain the tank to get the reg off for another dive, and overhaul the valve and VIP the tank when we got it back to the shop. That's a major PITA - and while backing off a quarter turn doesn't guarantee you can't jam the valve if you really crash into something, it does make it extremely unlikely. If the valve's on the stop even a minor bump could jam it.
Rick
--
Why a VIP? Tank rode for several hours with heavy salt spray and open valve - just had to check for possible salt water droplets in the tank.
Why an overhaul on the valve? In the attempt to close it we stripped the stem.
How'd it happen? The diver was a "don't back it off diver" who didn't even remember bumping the valve handle during the dive. That diver is now in the "back off a quarter turn" camp :)
 

ScottUgly

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I do not use the quarter turn. I use a slight turn. Not enough to actually move the valve. I stop at the point just before you can feel the valve moving. I prefer to have the valve completely open. I don't see how having the valve partially closed could be of any benefit.
 

electrix

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I do it because that is what I was taught. I don't think there is any mechanical reason for doing it but the last thing I do before a student gets in the water is check his valve if it does not easily move is it firmly closed or firmly open?
 

jewelofnile69

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I do not use the quarter turn. I use a slight turn. Not enough to actually move the valve. I stop at the point just before you can feel the valve moving. I prefer to have the valve completely open. I don't see how having the valve partially closed could be of any benefit.

I'm essentially the exact same and feel the same way. I do turn it open all of the way and then just make a slight (less than an 1/8th of a turn) back.
 

Wookie

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I do back my valve off a quarter turn. Valves without a designed back seat are usually backed off a quarter turn so pressure doesn't build (or a vacuum drawn) behind the disc making the valve difficult to stroke if the valve is fully open. The Navy taught that in Machinist's Mate 'A' School 30 years ago, and I've made it a habit ever since. It really doesn't matter with a scuba valve... OH, except for the poorly designed ones like the Genesis valves of 1996-1999. Remember them? They would get stuck on the back seat if you used the green discs, everyone had to swap them out for the black discs with the wee hole drilled in them to relieve back seat pressure differential.
 
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ScubaSteve

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I do not back mine off a quarter turn. I back it off only a smidge to make sure it is not open to the point of force and not at the hard stop. It is back only far enough to take it off that hard stop.

Edit

Seems like I vote the way Scottugly and Jewelofnile69 do.....
 

TSandM

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I do what Scuba Steve described. I HAVE opened a valve to the point where I was unable to close it underwater, and I don't want to have that happen when the closure isn't just for a drill . . .
 

ScottUgly

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I do what ScubaSteve does. He just did a much better job explaining it than I did. :wink:
 

Searcaigh

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I voted for quarter turn, but it probably is not as much as that.
 
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