Tank valve knob lock?

[Damselfish]

All the other things you mention as low probability are way more likely to be an actual issue than your tank accidentally getting turned off accidentally by bumping the knob while rec diving, which I think borders on the infinitesimal despite one case.

The reasons to reach your valves are more to be able to turn one off if needed becase of a reg malfunction. Or to turn it on - because you forgot to turn it on to begin with, not because it got accidentally bumped off. Or maybe someone got confused by the quarter turn thing and turned it off on you. Or maybe your dive buddy is a prank playing twit. Turning it on is not something you want to make harder.

Complicating equipment more than needed can bring its own risks.

 

[Damselfish]

nm

 

[Doc]

I'm with you so far....

...What leads you to say that this potential failure point is not worth considering?

and to my cable tie hack you say....

....Interesting idea, although that would be a hassle to remove probably requiring a knife. I was imagining more of like a twist open followed by folding down a separate tab or something to lock in place.

Adding your very own failure point, this one requiring engineering and injection molding.

I'd call George Foreman at Invent Help. You're on to something.

CU@DEMA

 

[PfcAJ]

If you bob your tank reach back and make sure the valve is open.

If you get snagged on something STOP and desnag yourself. Then reach back and make sure your valve is open.

Keep it simple.

 

[The Chairman]

However, does not the fact that you feel the need to reach back and make sure they are still open, indicate that you feel there is a possibility that they might not be?

I've only felt so compelled while in a cave. In OW, you should never, ever have to worry about it. If you're going to go into overhead, please, please, please take the appropriate classes. I suggest you take cavern and intro to get the techniques down. Then maybe some wreck penetration classes if that's what you want to do, or apprentice and full cave if that's more in line with your desires. At this point you don't even know what you don't know. Get the training before you put yourself in those situations. So, if you're not in an overhead environment, you simply don't have to worry about rolling off your tank. When I dive in an overhead environment, one of the things I do is to be sure that I can reach those valves, so if I do bump the ceiling I can reach back and be certain they are open. See? It's a matter of training. Get the training before you get into the situation where you need the training because that would be too stinking late.

The whole debate over "half a turn back" or "all the way open" for example is only relevant to extremely low probability scenarios.

I disagree... it's more emotional than anything. I worked with N, LN, H and LN in a p-chem lab at the UF department of chemistry. I've taken haz-mat and OSHA classes through the university and currently teach Tank Inspection Procedures. There's a lot of apocryphal information out there with little basis in reality, but rather based on emotion. Many people believe that their's is the only way simply because that's how they do it and everyone else is an idiot. Me? I back off a quarter turn because I am able to figure out if a tank is open that way. All the way open and all the way closed feel the same to me. A 1/4 turn off of full open has a certain wiggle to it, so I can tell if the tank is on. I don't care if you do it differently. I just stay consistent with how I'm doing it.

 

[PfcAJ]

I've only felt so compelled while in a cave. In OW, you should never, ever have to worry about it. If you're going to go into overhead, please, please, please take the appropriate classes. I suggest you take cavern and intro to get the techniques down. Then maybe some wreck penetration classes if that's what you want to do, or apprentice and full cave if that's more in line with your desires. At this point you don't even know what you don't know. Get the training before you put yourself in those situations. So, if you're not in an overhead environment, you simply don't have to worry about rolling off your tank. When I dive in an overhead environment, one of the things I do is to be sure that I can reach those valves, so if I do bump the ceiling I can reach back and be certain they are open. See? It's a matter of training. Get the training before you get into the situation where you need the training because that would be too stinking late.

I disagree... it's more emotional than anything. I worked with N, LN, H and LN in a p-chem lab at the UF department of chemistry. I've taken haz-mat and OSHA classes through the university and currently teach Tank Inspection Procedures. There's a lot of apocryphal information out there with little basis in reality, but rather based on emotion. Many people believe that their's is the only way simply because that's how they do it and everyone else is an idiot. Me? I back off a quarter turn because I am able to figure out if a tank is open that way. All the way open and all the way closed feel the same to me. A 1/4 turn off of full open has a certain wiggle to it, so I can tell if the tank is on. I don't care if you do it differently. I just stay consistent with how I'm doing it.

Going down an anchor line with the line behind your valve knob can for sure close the valve.

Everyone should be able to control their gas source. Sometimes wacky **** goes down.

 

[WetSEAL]

So basic divers shouldn't expect to get caught in a line on their tank knob, therefore it's pointless to add a basic safety feature that protects knobs from getting caught caught and closed in lines? By that logic, basic divers should also never carry a dive knife or scissors, because if getting caught in lines "shouldnt" happen to basic divers, they have no need for it.

In my opinion, thinking about and taking simple steps to reduce the chance of catastrophes shouldn't be something that only "advanced" divers think about. One doesn't have to be "advanced" to get caught in a line.

In fact, I think this is much more relevant to beginners, who have less experience, and are going to have a more difficult time thinking calmly and reacting to an unexpected tank shutoff underwater.

Out of the 300 people who've viewed this thread so far, already 1 of them has admitted that they got caught up in in something that caused his tank valve to accidentally close up....so although this is a small sample size, that suggests it's not so "impossible" as you suggest. Is it really a 1/300 event? Maybe not, but it's probably not 1 in a million either.

The fact that it was a drysuit hose, which is something that many people will be in close proximity to a lot of the time as opposed to just a stray line in the water, means that this is even more likely to have happened to someone else.

It just baffles me that you are all of the mindset that despite a known safety consideration, which has documented cases of failing, that there is no reason to even think about improving the design -- even if it could be a dead simple tweak for an anti-rotation lock.

Anyway, you all have sufficiently clarified that such a knob does NOT currently exist...which was the main question I came here with, so thanks for clarifying that.

 

[tbone1004]

Okay, so it's happened to someone at least once...which pretty much nullifies any argument that "this is a non-issue."

Thank you for sharing.

what @claymore experienced was operator error from a poor equipment configuration choice. You shouldn't solve that problem with a new piece of equipment, you should change the configuration to a more appropriate solution. In that case, run the drysuit hose like it is supposed to be run. I have hundreds of drysuit dives and have never had a drysuit hose anywhere near my tank valve, and I suspect that Claymore hasn't had any near misses since he changed his configuration.

The whole point of that circles back to an equipment solution to a skills and/or configuration problem. In this case you have two skills problems, and one potential configuration problem. I'm an engineer, so I'm with you on wanting to make sure everything is as good as it can be, but in this case you have to step back and look at the problem. In this case it is a valve turning off, multiple full rotations before closure, where the diver is oblivious that his tank valve was in contact with something, unable to reach his valve, and his buddy was unable to reach it.
So the skills problems are the diver is oblivious *not so easy to fix*, and doesn't know how to ask his buddy to check his tank valve *easy to fix*. The potential configuration problem is he can't reach his valve which is easily remedied by moving the bcd down on the tank.
Now, the big con to your potential solution is that it has serious ramifications for non-recreational divers in the form of the inability to feather valves which @The Chairman mentioned as a reason that you need to reach them. Your essentially negligible problem isn't actually a failure, just a nuissance, but a relatively common issue is a freeflowing regulator. If you had a valve that required two motions to unlock and turn, it would be very difficult to shut down the gas. The ability to quickly shut down that tank is HUGE in technical diving because every second longer it takes to turn off, the more gas is wasted. In a cave, that could be the difference in making it out or drowning.
Minor con is that it takes something that is idiotically simple and makes it unnecessarily complicated. You said yourself above that you want to remove points of failure. This type of valve adds several failure points that do not exist in a standard valve.

So, do the valves exist? yes, they exist. They are standard on SCBA tanks for firefighters. They could be very easily adapted for the scuba market, but the one potential issue they solve creates more with much more severe consequences.

 

[WetSEAL]

what @claymore experienced was operator error from a poor equipment configuration choice. You shouldn't solve that problem with a new piece of equipment, you should change the configuration to a more appropriate solution. In that case, run the drysuit hose like it is supposed to be run.

Every diving accident ever to occur can be blamed on user error...but that's a cop out answer.

Good designers don't blame their users for messing up, they fix the design so that form of error can't happen again, reducing the surface area of user-blameable errors.

In this case, it would be trivial to modify the equipment so that this user error could never happen.

So, do the valves exist? yes, they exist. They are standard on SCBA tanks for firefighters. They could be very easily adapted for the scuba market, but the one potential issue they solve creates more with much more severe consequences.

I searched for SCBA tanks and could not find what you are referring to...could you provide a link?

 

[tbone1004]

Every diving accident ever to occur can be blamed on user error...but that's a cop out answer.

Good designers don't blame their users for messing up, they fix the design so that form of error can't happen again, or is less likely.

In this case, it would be trivial to modify the equipment so that this user error could never happen.

and the consequences for those that need to quickly turn the valve off? Is this problem *of which I am not aware of any documented deaths, only near misses*, worth risking the lives of those that need to turn off quickly for feathering *of which I can think of several where the several second delay in being able to shut the valve off could very well have killed the diver*.
Another issue with this type of valve is that when doing things like ice diving, there is a high propensity for valve/regulator components to freeze. This type of valve if frozen while open would be completely unable to be shut off *occurs REAL fast when ice diving with a freeflow* and the mechanism that would be the second motion for the "lock" would be frozen. Shutting that valve off can allow it to thaw while you are still diving, but if it was stuck on, which your design choice would, then all of the gas would be wasted with no ability to shut it off