Quarter turns

[JahJahwarrior]

Full open, not backed off. Diving in side and no mount caves I bump my valves against plenty and have never had a hard time closing any of them...but apparently others have, so in the battle of the anecdotes, siding with caution, it sounds like leaving them fully open is not good.

But I'll keep diving with mine open. I have had fill operators who don't open them fully get confused and have to check the tanks when filling sidemount tanks.

 

[Rich Keller]

I always do about a quarter turn back, never really measured it though, it is always different every time. First reason is so it cannot get jammed (actual term is galled) in the open position. Second reason is so the valve is not wearing on the exact same spot every time.

 

[bygolly]

I see no harm in using the 1/4 turn to back off from fully open. It signals to someone else who may be rechecking the valve that it is indeed "open" to some degree. Further checking will soon indicate whether it is nearly fully open or nearly fully closed. Someone checking a fully open valve may mistake it for a closed one and give it a good reef which may jam it open. Not always dangerous when diving with a single tank and K valve (inconvenient maybe) but may be problematic in a doubles or Y/H valve combo when a needed shut down cannot be performed. BTW, I have actually seen people struggling to open an already opened valve.

 

[AfterDark]

Not quite a 1/4 turn I just take in off the stop. See Jim's post valve stuck open. Also when I was trained in HP bottle handling it was "good shop practice" to back off a bit after hitting the stop so that the valve wouldn't get stuck open. Once the valve is open that far backing off even a 1/4 turn doesn't restrict the valve by any noticable difference.

 

[ajduplessis]

My dive gear includes various cylinders. Equipment is expensive and I therefor look after and maintain my gear to very high standards. Thus 1/4 turn off from full open to help protect and prolong valves for me. Thou I have not seen "stuck" valves due to impact I do recognise the possibility.

 

[JahJahwarrior]

I always do about a quarter turn back, never really measured it though, it is always different every time. First reason is so it cannot get jammed (actual term is galled) in the open position. Second reason is so the valve is not wearing on the exact same spot every time.

I don't understand the wear. All of the threads are engaged no matter the position, and the seat is either touching the orifice (valve closed) or not (valve open). How open you have it will affect flow rates, but I don't see how it changes wear on the valve.

How many of you open and lubricate your valve yearly?

 

[g1138]

On fully, then back a little ways, then back on fully but using only the tips of my fingers.
Most modern valves can't be stuck in the on position where you would actually need a wrench to turn it back. You can get it to a point where it is really stiff to turn off from the ON position, but if you don't wrench your valves open with a lot of brute strength it isn't so much an issue.

If you were to swim and bump your valve on an obstruction and it kept it locked open then I think you probably already cranked on your valve too hard or you got a bit trigger happy on your scooter.

 

[ScottUgly]

It signals to someone else who may be rechecking the valve that it is indeed "open" to some degree. Further checking will soon indicate whether it is nearly fully open or nearly fully closed.

This is the primary reason that I hear from instructors teaching this. You can do the same thing without partially closing the valve. See post #3 and more detailed description in post #7 from ScubaSteve. I still see no benefit to partially closing the valve.

 

[tstormdiver]

Absolutely not! It is either on or off, all the way,... then there is no question of which way is which. If a Dive Master turns it back 1/4, I will jump in, reach back & turn it all the way on. I've had my cylinder turned off too many times by someone that couldn't tell if it was partially on or partially rolled back. Thank goodness I can easily reach the valve, if needed.

 

[freewillie]

I do it because that is what I was taught.

That was going to be my answer. I open the valve fully then turn it back slightly if for no other reason that is what I was taught to do and seems to be the standard.