Tank Valve Stuck Open

[NorCalDM]

Bleeding it dry was what I did. I was curious if there were other options.

Even after it was empty the valve didn't budge, but after sitting in the sun for 5-10 minutes (it was a sunny and warm day) it turned easily.

The sun warmed the metal enough for it to expand and allow you to turn it which tells me when it was opened a fair amount of force was used and when the cold water hits the valve it contracts and seized. I’ve always been one to turn a valve back slightly no matter what type of valve it is except a ball valve. To me anything you continuously bring against a hard stop wil cause damage over time.

 

[JamesBon92007]

OK, that's finally settled. Until the cave divers show up

 

[stepfen]

Once (I think it was our very first dive without a guide) my buddy by mistake turned an already closed valve clock-wise to "open" it. As a result it got stuck closed so we couldn't dive.
The plastic/rubber handle was rotating but not the valve itself. We did try several things. At the end the only thing that worked was this: we sandwiched the handle between the flap and the body of a metal weight belt buckle. Then we wrapped tightly the belt around the buckle/handle and rotate. It did save as that dive.

 

[scubarushu]

Thanks for all the info! I’m pretty sure neither I nor my buddy cranked it open hard, but since it was a rental tank I don’t know what condition the internals were in.

Been thinking about getting my own tanks for a bit, but haven’t pulled the trigger on that yet. Isn’t that how divers measure a particular type of addiction?

 

[JamesBon92007]

You never know for sure. I grabbed my favorite tank the other day and the valve was leaking, and I take good care of my equipment. The trouble is that I have too much stuff and can't remember which thing I did what to, and when. I'm now trying to make a log of my repairs.

As for the addiction, when I started diving everyone I knew owned their tank. I guess we thought renting was for when you were on a vacation. It all depends upon how often you will use it and add up the costs and compare buying vs renting. I've used a lot of tanks on dive trips and have had very few problems with them.

 

[Fibonacci]

On a recent dive trip to Montague Island, three of the rental tank valves stuck open... at changeover time the crew raced round with a pair of multi-grips on the knobs to get them to budge!
Not a good look, but judging by the galling on various tank knobs a complete overhaul of all their rental valves was long overdue...

 

[rick00001967]

OK, that's finally settled. Until the cave divers show up

i am not a cave diver

but the reasoning behind opening valves all the way vs opening and then closing slightly is so when the diver needs to shut down or open a valve in an emergency, there is no possible confusion on whether the valve is open or closed. it is either open (all the way) or closed (all the way). no in between. this can be critical. in recreational diving, not so much.

i personally still ask my students to be gentle with valves and to back off slightly after opening. no more than 1/4 turn.

 

[rsingler]

when the diver needs to shut down or open a valve in an emergency, there is no possible confusion on whether the valve is open or closed

Isn't it funny how we're all taught? I was taught exactly the same rationale, but exactly the opposite thing to do for that very reason, lol! Here's how my training went (and why I still do it that way):
1) there are divers (yes I know, not you or me) who have trouble with the "lefty loosey, righty tighty" thing.
2) If someone "helps you" open your valve when it's already open, and thinks it's stuck because they can't quite remember which way to turn it, they might strip your valve threads, or destroy the plastic knob, by forcing it hard CCW when it's already open. There may indeed be confusion about whether it's open or closed, if the valve knob doesn't move.
3) Therefore, I was taught to crack it back, so that when someone opens it again (like the young DM at the rail waiting for your giant stride), they quickly feel it come up against the stop, and stop trying.

Yes, I acknowledge that an easily turning left post may roll closed against a ceiling, so what you cavers do is just fine by me.
Me, I crack it back a hair, and I teach my students to do the same, for the reason above.

 

[TrimixToo]

Isn't it funny how we're all taught? I was taught exactly the same rationale, but exactly the opposite thing to do for that very reason, lol! Here's how my training went (and why I still do it that way):
1) there are divers (yes I know, not you or me) who have trouble with the "lefty loosey, righty tighty" thing.
2) If someone "helps you" open your valve when it's already open, and thinks it's stuck because they can't quite remember which way to turn it, they might strip your valve threads, or destroy the plastic knob, by forcing it hard CCW when it's already open. There may indeed be confusion about whether it's open or closed, if the valve knob doesn't move.
3) Therefore, I was taught to crack it back, so that when someone opens it again (like the young DM at the rail waiting for your giant stride), they quickly feel it come up against the stop, and stop trying.

Yes, I acknowledge that an easily turning left post may roll closed against a ceiling, so what you cavers do is just fine by me.
Me, I crack it back a hair, and I teach my students to do the same, for the reason above.

(1) is a thing. I know people for whom "all the way open so I can't go the wrong way" is absolutely the right thing for them. As a former wrench, though, I like to think my odds are pretty good. ;-)

(2) is one reason all my knobs have metal inserts. I replaced all the ones that were all-plastic immediately after the first time I saw one stripped. (I carry the all-plastic ones to give away on the boat if someone has a need, but advise them to buy a Real Knob when they're back. I will run out soon.) Even if you strip the knob off the metal insert, there's enough leverage left to close a valve (and reopen it if appropriate). However, I think the chances of stripping any of the threads are remote. The valve insert will dead-end in the valve stem bore, and the valve stem will fail before that thread would ever fail. The threads on the valve stem shaft just keep the knob from falling off.

That said, if Helpful Harry the DM touches any of my valves on my way into the water, I'm sitting back down to get them back where I want them by feel so I know where they are. This is irritating to me and the people trying to get to the ladder behind me, and usually quite embarrassing for Helpful Harry the DM, but that's life.

(3) I still do out of habit (with one exception that's outside the scope of the Basic forum). It's harmless unless one is in doubt about which way to turn the valve IMO, but I think there's no real reason any more.