Why do you not turn a tank full on ?

[VTernovski]

Genesis once bubbled...
do you want to guess which way to turn the valve, or KNOW which way to turn it B]

This is a non-issue for me. It's a second nature, I never have to even think of it. Must have had a lot of Play-School toys when i was a kid or somehting, lol.

 

[neil]

Squasher once bubbled...

Arent you suppose to know your equipment?? Test your gear before you hit the water? e.i. turn your tank valve on, close it, breath through the reg until nothing comes out. count how many breaths you took. than before every dive breath through your reg more than the number you counted.

With all due respect Squasher, you've made a simple task quite complicated. How about I look at my SPG and take a really big breath on the reg. Tank shows full, needle doesn't move. My air's on. Obsessive compulsive left tug on the valve and I'm done. Then there's the buddy thing, but someone else can handle that...

Neil

 

[d33ps1x]

RICHinNC once bubbled...
It is a good thing to have old people around every now and then.

In "the old days" the machining process of valves wasnt that great and if you opened a valve to the end of the threads.... there was an excellent chance it would leak like a screen door in a sub...

so...you would open the valve full .....then take it back about 1/2 a turn...and in doing that you would prevent possible damage to the valve and any unnecessary leakage.

About time someone came out with the right answer. I usually toss the person who turns my valve back a quarter turn without asking me first off the boat with their's fully closed.

Although I do like some of the other urban myths out there.

Way to go old dude!

 

[GDI]

:doctor:
These are all pretty good reasons for turning the valve open all the way and back 1/4 turn. But another reason is this (Did I miss this in the above replies)
Lets not forget basic scuba physics. Gas becomes more dense as we descend. If a diver drops down to depth and notices there is difficulty in breathing and his SPG is bouncing with every breath he takes then his valve is not fully (less 1/4 turn) open. At shallow depth he will breath easy again and not notice this effect. The valve will not pass the denser air - open the valve

 

[FreeFloat]

RICHinNC once bubbled...
my thing is to remember to have my valve lever in the down position so that i have no reserve air but full access to all air....
know what i am talking about???? know what kind of valves i have??

Yeah, I dived one this afternoon