scubarushu
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Went diving last weekend. Woohoo! Surfaced with ~500 psi in my rented AL80 after my first dive and couldn't get the tank valve to budge. What would you do if this happened to you?
Tank Valve Stuck Open
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Do you mean to say that the valve was left in open position? If yes, then I would bleed the tank dry by purging remaining air from the 2nd stage and then take my reg off. Its a rental tank and the valve needs to be serviced.
JamesBon92007
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And people these days say not to turn it back a little after opening it all the way.
I would do what Compressor said.
I would do what Compressor said.
Had that on 20 odd rental tanks so far, @Compressor's method is what I do as well. (Stripped out handwheel, jammed valve or bent stem)
If it was my own tank, I'd remove the handwheel and use a wrench on the stem.
With proper maintenance I've never seen it.
Cameron
If it was my own tank, I'd remove the handwheel and use a wrench on the stem.
With proper maintenance I've never seen it.
Cameron
TrimixToo
Contributor
Some of the knobs are all plastic. If turned too hard in any direction, they strip. This could be a problem for valve shutdown or feathering a valve to control a freeflow. I replaced every single one of mine after seeing this happen to someone else. All my knobs have molded in metal inserts, and I have never seen one of those strip or fail in any other way.
One perhaps likely knob-stripping suspect is the ever-so-helpful crew member who "makes really sure" everyone's gas is on before they splash by twisting the knob with excessive vigor. Another is the newbie shop monkey who thinks the valves need to be shut tight, leaving the knobs almost stripped, and maybe even setting up that ever-so-helpful crew member for undeserved blame just because that unlucky person happened to be the last to touch it (grin). Then, of course, there are the divers...
OP
scubarushu
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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.
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.
OP
scubarushu
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Just a smidge seems reasonable (and reasonably distant from the 1/4 turn argument?). Would it help avoid issues like this and/or being unable to shut the valve underwater in exigent circumstances?
JamesBon92007
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No-one can say for certain if it would have helped in this particular case, however this is precisely why they taught us to back off a little when I was certified in 1969. They didn't tell us to do a full 1/4 turn, just a "smidge" like you said. I guess the 1/4 turn must have come later. Maybe a smidge wasn't enough for someone. I just do it by feel--enough so it's not jammed in the open position.
AfterDark
Contributor
How did this happen all the experts tell me that modern valves CAN'T get stuck open? Could these experts be wrong? Every job / activity that I've done that involves valves of any kind I've been told the same thing, not by experts, but by people that work / use the valve(s) don't jam the valve open, back it off a bit from full open so it doesn't get stuck. Doesn't matter if it's a water faucet (valve) or a scuba tank valve, cutting torch bottles, any valve except a check valve can be jammed opened.
Ok so coming from a gear tech, the whole turn back or don't turn back debate.
A) If you full palm grip and turn any valve, hit the last turn and then budge it more to "make sure it's fully open", then yes you should turn back a little. This is a preventative action for a problem the user causes.
B) If you use your fingertips or loose grip and gently roll the valve until it stops, then you don't need to turn back. Loose grip means when the handwheel stops, your hand slips and rolls over the handwheel. This is also preventative action, but additonally prevents long-term wear/tear damage to the valve.
This is what the inside of a valve looks like. (For those wondering, I killed the threads on purpose, it's a demo/out of service valve)
The more likely issue from doing method A is usually prematurely wearing out annual service parts & non-standard-service parts of the valve. Folks who do the former (A) will overtime round out the inner square-shaped turn post or the handwheel that slots over the turn post. Both those parts are non-standard service parts. As in they aren't intended to be replaced during the life of the valve, assuming people don't abuse it. Practically speaking a lot of divers do, because they budge the valve more after it stops turning. Most do it without knowing, because they palm the handwheel.
Handwheels not reinforced with metal, but full plastic will strip and eventually freespin (after years of abuse). Handwheels reinforced with metal (ie Thermo, XS Scuba, Sherwood) will instead round out the Turn Post after years of that abuse.
In both cases, the handwheel will freespin leading you to not be able to turn your tank on or off per normal operation.
In a rare instance with modern valves, yes you can still seize the valve stuck in the open position; especially if you're that individual that turns it like I described in A, you're using a metal reinforced handwheel, and you're heavy handed.
With the metal reinforced handwheels, you can turn the Seat Plug (made of brass, really the whole valve is soft chromed-brass) so far that you grossly warp the threads. If you haven't figured it out: The handwheel spins the Turn Post, which spins the Seat Plug, which plugs or unplugs your valve closed/open. TA-DAH!
You will slowly warp and bend the brass threads on the seat plug, making them out of tolerance and making the valve stiff to turn. Force it enough and in combination of metal compression/expansion from a cold water dive to warm weather California surface interval, you can cause the seat plug to seize.
A) If you full palm grip and turn any valve, hit the last turn and then budge it more to "make sure it's fully open", then yes you should turn back a little. This is a preventative action for a problem the user causes.
B) If you use your fingertips or loose grip and gently roll the valve until it stops, then you don't need to turn back. Loose grip means when the handwheel stops, your hand slips and rolls over the handwheel. This is also preventative action, but additonally prevents long-term wear/tear damage to the valve.
This is what the inside of a valve looks like. (For those wondering, I killed the threads on purpose, it's a demo/out of service valve)
The more likely issue from doing method A is usually prematurely wearing out annual service parts & non-standard-service parts of the valve. Folks who do the former (A) will overtime round out the inner square-shaped turn post or the handwheel that slots over the turn post. Both those parts are non-standard service parts. As in they aren't intended to be replaced during the life of the valve, assuming people don't abuse it. Practically speaking a lot of divers do, because they budge the valve more after it stops turning. Most do it without knowing, because they palm the handwheel.
Handwheels not reinforced with metal, but full plastic will strip and eventually freespin (after years of abuse). Handwheels reinforced with metal (ie Thermo, XS Scuba, Sherwood) will instead round out the Turn Post after years of that abuse.
In both cases, the handwheel will freespin leading you to not be able to turn your tank on or off per normal operation.
In a rare instance with modern valves, yes you can still seize the valve stuck in the open position; especially if you're that individual that turns it like I described in A, you're using a metal reinforced handwheel, and you're heavy handed.
With the metal reinforced handwheels, you can turn the Seat Plug (made of brass, really the whole valve is soft chromed-brass) so far that you grossly warp the threads. If you haven't figured it out: The handwheel spins the Turn Post, which spins the Seat Plug, which plugs or unplugs your valve closed/open. TA-DAH!
You will slowly warp and bend the brass threads on the seat plug, making them out of tolerance and making the valve stiff to turn. Force it enough and in combination of metal compression/expansion from a cold water dive to warm weather California surface interval, you can cause the seat plug to seize.
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