Lessons My sidemount cylinder valve spun itself completely shut during a dive

[inquis]

I don't do the half turn back, and I don't partially open.

Was this dive from a commercial boat where a "helpful" deck hand may have been confused by the non-standard valve and closed it without your knowledge? (I've definitely had that happen before.)

 

[jstotz]

Was this dive from a commercial boat where a "helpful" deck hand may have been confused by the non-standard valve and closed it without your knowledge? (I've definitely had that happen before.)

Negative. Just us three friends doing a shore dive that I found online and researched. And if one of my friends had for some reason shut off my tank they would have shut off both and they would have done it all the way. I really think that the strong and varying currents and continual arm movements had something to do with it.

 

[inquis]

Has anyone ever heard of this happening before?

Only in the context of grinding through a wiggly-tight cave restriction, never from arm friction.

My experience: I sidemount Lola valves, which are a) oversized, b) very grippy/rubberized, and c) EXTREMELY low resistance to spin. If ever there was a scenario that might be prone to arm friction, that is it. I've never found the valve being noticeably different than fully open at the end of a dive. That includes multi-hour dives in current with arm movements that could bump the valve. (Pull & glide when cave diving with a CCR.) Arm friction after only 20 minutes? I'll go with "unlikely" as well.

Speculation aside, you seem to have a plan to investigate. Let us know what your pool time tells you.

 

[USdiver1]

If it were me, I'd be waterboarding those two 'friends' about now.

Just Sayin'

 

[tursiops]

And if one of my friends had for some reason shut off my tank they would have shut off both and they would have done it all the way.

But the point is they were (maybe) NOT trying to shut off your tanks, but rather to make sure they were open. Turn it the wrong way, then back a "quarter turn." Which turns it off, then back on just a quarter turn. Note it was your right tank with the "backwards valve;" easy to make that mistake.

 

[jstotz]

But the point is they were (maybe) NOT trying to shut off your tanks, but rather to make sure they were open. Turn it the wrong way, then back a "quarter turn." Which turns it off, then back on just a quarter turn. Note it was your right tank with the "backwards valve;" easy to make that mistake.

Ahh! Yes, I see what you're saying now. I'll start interrogations

 

[tursiops]

Ahh! Yes, I see what you're saying now. I'll start interrogations

LOL. I suspect a gentle question along the lines of, "Did one of you help me out by checking my gas before our dive?" would go better than an "interrogation."

 

[iliketopetsharks]

Note it was your right tank with the "backwards valve;" easy to make that mistake

"Backwards valve"? They close counter clockwise or what?

 

[inquis]

"Backwards valve"? They close counter clockwise or what?

For reasons unknown to me, some people don't think in terms of "CCW = open". They think "top of the valve away = open": this works great for a standard valve in a tank rack, which becomes ingrained over thousands of repetitions. Unfortunately, it also closes a non-standard valve.

 

[iliketopetsharks]

For reasons unknown to me, some people don't think in terms of "CCW = open". They think "top of the valve away = open": this works great for a standard valve in a tank rack, which becomes ingrained over thousands of repetitions. Unfortunately, it also closes a non-standard valve.

Yeah it's odd, maybe because a growing proportion of the populace has never worn an analog watch?