Half a turn back

[JahJahwarrior]

It helps keep valve from sticking open.

Not much of an issue with modern valves with the correct amount of torque used to open them.

It lets a tank checker know the valve is open. If it doesn't move one way, they might think it was closed, and close it.

1- why are you letting someone else touch your gear?
2- anyone with a c-card should know righty-tighty-lefty-loosey.
3- if you let someone who can't tell if a valve is open touch your gear, just imagine what else they could screw up! "hey man this second stage fell off...I checked it and it didn't turn so I assumed it was off and just kept turning until it...fell off..."
4- just as likely that they'll think the valve is only 1/4 turn on, and try to do you a favour by turning it the rest of the way.

It protects the valve and/or orings by reducing pressure on them.
It's a valve, not a regulator. It is designed to contain and control the fill pressure limit of the tank. If it was bad to leave pressure on the parts of a valve, then it would be bad to leave tanks filled. Rebuild your valves every so often (at the minimum, rebuild it every hydro) and don't fret, leaving the valve open won't hurt it anymore than leaving it closed.

In short, I turn valves all the way, and don't let other people touch my valves.

 

[lemon]

In short, I turn valves all the way, and don't let other people touch my valves.

I couldn't agree more. Nothing that I hate more than for someone to reach for and manipulate my valve, especially once I am geared up and ready to go.

 

[boomx5]

I'm not worried about some boat monkey or DM touching my valves. No one is allowed to touch my valves without my permission. That's my gas they are screwing with and I'll cut someones fingers off with my itty bitty baby DIR knife! J/K I also believe in opening them all the way as not to cause confusion in a stressful situation or in case of a failure.

 

[Gerbs]

Another thought, and to add oil to the fire:

How do you check that the valve is open? You either try to close it (if it turns, then it was open, you return it) or try to open it further (if it turns, keep turning!).

If you open the valve fully against the stop it may or may not stick, as in require a bit more torque to make it start turning when trying to close it.

If you check by trying to close, then you might think it is not open, especially if being gentle. Turning more might damage the valve and might make you look silly.

If you check by opening, then you might miss that stiff closed-by-a-gorilla valve on the rental tank.

For what it's worth, my valve procedure when setting my stuff up:

1. Attach both 1st stages (I use an H-Valve)
2. Open both valves slowly
3. Shut the valve which supplies the reg with the gauge
4. Attach the Inflator hose (I've just tested that valve in the hose)
5. Check inflator and regs for function. Use shut reg until it stops breathing.
6. Check that the SPG has gone to zero (and doesn't stick... don't want to read more gas than I have!)
7. Open all valves.
8. leave valves so that there is a feelable movement until it hits the stop.

The feelable movement tells check-by-opening that it is now against the end stop, and that it is not just a stiff valve left closed. Similarly, because it is not sticking on the stop, a check-by-closing will find a readily moving valve and not try to force the issue.

In either case, checking by turning the valve towards *and* away from its end stop should find the actual state of all combinations of stuck open, stuck closed and stiff valves.

Just my €0,014.

Gerbs

 

[Matt P]

I personally witnessed a diver open his tank and then turn it back 1/4 turn. We didn't don our gear until 30 mins later. Before donning he "opened" the tank again this time leaving it only about 1/4 turn open. The problem didn't present itself until we hit 70 FSW and he wen OOA. Not good. Open it all the way.

 

[LeadTurn_SD]

Another thought, and to add oil to the fire:

How do you check that the valve is open? You either try to close it (if it turns, then it was open, you return it) or try to open it further (if it turns, keep turning!).

If you open the valve fully against the stop it may or may not stick, as in require a bit more torque to make it start turning when trying to close it.

If you check by trying to close, then you might think it is not open, especially if being gentle. Turning more might damage the valve and might make you look silly.

If you check by opening, then you might miss that stiff closed-by-a-gorilla valve on the rental tank.

For what it's worth, my valve procedure when setting my stuff up:

1. Attach both 1st stages (I use an H-Valve)
2. Open both valves slowly
3. Shut the valve which supplies the reg with the gauge
4. Attach the Inflator hose (I've just tested that valve in the hose)
5. Check inflator and regs for function. Use shut reg until it stops breathing.
6. Check that the SPG has gone to zero (and doesn't stick... don't want to read more gas than I have!)
7. Open all valves.
8. leave valves so that there is a feelable movement until it hits the stop.

The feelable movement tells check-by-opening that it is now against the end stop, and that it is not just a stiff valve left closed. Similarly, because it is not sticking on the stop, a check-by-closing will find a readily moving valve and not try to force the issue.

In either case, checking by turning the valve towards *and* away from its end stop should find the actual state of all combinations of stuck open, stuck closed and stiff valves.
Just my €0,014.

Gerbs

Hi Gerbs,

I understand what you are saying and it makes perfect sense, however the problem lies with people getting distracted and forgetting which way opens and closes the valve.

Opening the valve then backing it off 1/4 turn becomes a problem for some people if they become distracted while setting up their gear and forget they've already opened the valve; they then close it a few minutes later believing they are opening it, and then OPEN by 1/4 turn.... the result is the "feelable" movement you describe, but in a valve that is only 1/4 turn open :shocked2:

That is why many of us are suggesting the valve should always be either fully open or fully closed, nothing in between.

Best wishes.

 

[D_B]

I've experanced the tightend by a gorilla and stuck closed thing (took two hands to open it)

just turn it gently, I do all the way open then back a smidge , not even an 1/8th of a turn, just enough so it's not resting on the stop

 

[sphenisc]

Thanks for all the input! I hadn't realised it was quite such a point of contention. Lucky I didn't ask about DIN v A-clamp.

 

[SolarStorm]

The new husband watched his new wife make a roast on Sat night. She was really trying to do it just like her mother did. Same marinate, same spices, same cut etc. When she was all done, she dilligently cut the end off the roast and put it in the oven. It was fantastic, best roast he ever had. So on the following saturday, they invited the parents over for supper, eager to show of the new place and cook for their parents.

Well the evening started off by the "boys" going outside for a beer and chainsaw talk, while the women prepared the meal.

"How does he like your cooking?" the mother of the new bride asked.
"He loves it!, and I owe it all to you?" replied the new bride.
"But I have just one question? I follow your recipies to the letter and they always turn out great. But why do we cut the end off the roast before we cook it?"
Mom looked confused and replied, "Well I don't know about you, but I never had a roaster big enough for the roast"

My point here, is that I have read lots on valve freeze, DM error etc. I have no problem with routine. As a pilot, my preflight is identical each flight. But I still look at what I am doing and why and will change if new information is available.

I am a new diver so cant tell you why, but it doesnt sound like this is solidly grounded amongst the instructors other than to say "Cut the end of the roast off". This to me leads me to lean towards the "Dont touch my gear" crowd between me and my buddy.

 

[JahJahwarrior]

at DEMA, I saw a product that reminded me of this thread. It's a valve knob with two inserts. As you turn the valve on, the green insert slides out to cover the red one, so when its' fully on, there is no red showing, only green.

It was a quality piece of manufacturing and I was impressed at the design and how simple, and unlikely to break, it was. Plus, the company reps were real polite and nice.

I don't remember the company name, but I have some photos of the product, perhaps one of them has the company name in it? I'll try to put some photos up here eventually.