Why close the valve 1/4 or 1/2 turn???

[beautybelow]

There is a lot of stupidity and incompetence out there, I agree. I have never had anyone tell me not to check their air, most thank me. If somoene told me not to, I wouldn't though. Righty tighty, lefty loosey...see....I can do it!

 

[dhampton82]

Sorry for my english!! Thanks!!!
Manuel

I think that everyone did a great job of answering you question, and taught me something that I didnt know.

I would like to add though, that your english was perfect, alot better then mine and it is the only language I know! Also, welcome to the boards!

 

[scuberd]

I always teach my students to have the valve either all the way open, or all the way closed. I'd rather have a stuck open valve than a valve 1/4 open as can be the case.

 

[Penguinboy]

I agree with most of what has already been said here. From what I gather it is an old practise to prevent gas pressure turning the valve so tightly it would take a spanner to get it off.

However I believe most modern valves will not do this so I have been advised to either leave it as tight as you can easily turn it, and sometimes even turn it a little furthur than this so its tightly open. The reasoning behind this is that if it is touch-tight and gets bumped, or knocked in a dive it can close, whereas if it is a little tighter it will not (or should not!) close any.

Again, matter of personal preference. I myself am too inexperienced to give a definitive answer but here is what I have been told.

 

[The Chairman]

Old school or not, I am responsible not only for ME, but my buddy. You can be sure that a quick twist of the valve is in my buddy check. That and I ask them to breathe on their reg while looking at the SPG. No swings of the pointer means that the tank is %100 open... which is a GOOD thing.

 

[Penguinboy]

That and I ask them to breathe on their reg while looking at the SPG. No swings of the pointer means that the tank is %100 open... which is a GOOD thing.

Good point Netdoc. I learned this in PADI OW (not so long ago!) and it seems like a great little 10 second thing to have in your Buddy Check before jumping in.

 

[Teamcasa]

Old pressure valves would get stuck in the open position or in some cases break the valve if opened to the stop. I back the valve off all the way and just insure its not at the wide open stop.

Dave

 

[300bar]

The only good answer came from the Penguinboy ,it is an "old school" trick we had to do just because the valve would /could get stuck due to the pressure changes (no englisch is not my native language)We where told that the valve would freeze up and therefore could get stuck in the open position and you would naad a spanner to get it loose again.

 

[fairybasslet]

No swings of the pointer means that the tank is %100 open... which is a GOOD thing.

This happened to me at depth, (swings) but not until I had breathed about half my tank. It was weird.

 

[ba_hiker]

Most dive instructors and dive masters always like to check the air on customers tanks before they jump in the water. It is an easy check to turn the valve a quarter turn open, and then back to the originial position. We do this without the customer noticing but it is a quick easy way to make sure that the tank is on before they jump into the water.
Brent

I always notice. I often dive from boats where the DMs routinely do this. I appreciate that thay are concerened about my safety, but I ALWAYS do a breathing check after anyone touches anything on my air supply. So I often find myself checking the regs and bc inflator, while fully setup, on the edge of a bouncing boat, holding up others who want at the water.

I don't complain about this because they are trying to ensure my safety.

On occasion I have had DMs turn the air compleatly OFF then back ON. This screws with the connection between my computer (a vytec) and the pressure transducer, requireing that I recode the unit, and more time... I do complain about this. Its really a pain in the ****.