Regulator failure on a solo deco dive

[Grantt]

Great story. Thanks for sharing. I'm glad this worked out well and you learned a lot from the experience.
As pointed out, that nut loosening happens when the 1st stage rotates instead of the wheel. This is easy to check and fix pre-dive. At a bare minimum, I carry three allen keys in my kit, DIN tank plug, 1st stage plugs, and the one for that nut.
In water, for this issue or something similar, I would suggest practicing feathering the valve. This will preserve the gas in the functioning tank as much as possible and help with the off-balance issue you encountered.

I'm going to listen to your lesson learned here and get a hand mirror as well. I primarily dive twins.

 

[JohnN]

This past Sunday, I went for a dip in my local large body of water, Lake Tahoe. My typical dive is right around 100 minutes, on air, with some mandatory deco, and Sunday's dive was pretty typical. I went to Sand Harbor and dove Diver's Cove (not my favorite, but they shovel the snow here, so getting to the water is easy). Temps were around 32F/0C outside and 44F/7C in the water. I was diving two HP100s sidemount. In the parking lot, I had some trouble getting a reg to seat. I'm not a reg tech (yet), so forgive the following: the bit that takes an allen key and holds the DIN o-ring was a little loose. I tightened it by hand, put everything together, confirmed it was working, and thought nothing of it.

The first part of the dive went swimmingly. I took some pictures at the Project Baseline station to report on visibility, and then made my way to the deep portion of the dive. About an hour in, the reg that hadn't been seating properly started to bubble a little. When I reached back and grabbed the SPG to check tank pressure, the movement on the reg dramatically increased the amount of bubbling. At that point, it was time to turn the dive, obviously. I had 1600 psi in the free flowing tank, which I shut down, and 2,000 psi in the one I'd switched to. I also had 17 minutes of deco at 10 feet to complete (GF 65/80). On the ascent, I tried turning on the free flowing cylinder again, and it seated and worked for a couple breaths before starting to free flow again. I finished my dive on the other cylinder, even staying in the shallows for another 10 or so minutes after clearing my deco obligation. Ultimately, I exited with 600 psi and 1600 psi after 97 minutes, and the worst part of the dive was being lopsided from only breathing one tank.

I hesitated to post anything about this because it didn't even fluff up my SAC rate. It was a dive site I know well, using equipment I'm very comfortable with. I had factored in such issues and had plenty of gas to complete my deco, even considering one cylinder completely lost, which it wasn't. I've done more than 150 solo deco dives, and this is the first real incident. Even though the reg failed at basically the "worst" time (i.e., after I'd already racked up nearly the full amount of planned deco), planning, familiarity, and training made it a non-issue.

I recently picked up a set of doubles with the plan of re-familiarizing myself with the setup. I've been diving SM exclusively for a couple years, which I switched to from doubles. It occurred to me that the experience I described above would be different in a couple meaningful ways had I been in a twinset. First, identifying and addressing the problem would have been slightly more difficult with it behind my head. Second, after addressing the issue, I would have had access to all the remaining gas, not just some. A bit of a wash, but it has made me look at getting a hand mirror.

This is one I'm going to keep from my very understanding wife, but I wanted to share it somewhere, hopefully for someone's benefit. Safe diving!

View attachment 760024
Showing the camera the free flow while on deco

Well done !!

Superior divers
Use their superior skills
To avoid situations
Where their superior skills
Are needed

 

[Bigbella]

I had the same issue with a DIN reg (Aqua Lung). The tech told me that it is a common problem caused by twisting the body of the first stage rather than the knob when you remove the reg from the tank. If you do a little bit each time, before you know it you have backed out the bolt. It never happened to me before and now I am more aware of it.

I dive DIN almost exclusively -- almost cannot recall the last time I attached a yoke, and have yet to loosen a properly-torqued valve stem, over thousands of dives.

This incident in Tahoe likely resulted from piss-poor quality control from the manufacturer, given its age and usage (just a few months, it was claimed); and something that has been brought up on a number of threads, over, sadly, a number of brands.

When I worked at a shop, years ago, there had been a time when regulators, across several major brands, were seldom ever torqued to specifications; and it was often the newbie's responsibility to ensure that that was taken care of -- one of the few drawbacks to online purchases, these days.

You never know.

I don't know whether I would have used that regulator with just a hand-tightened connection stem, especially after difficulty seating it -- on a dive which was likely to involve obligative decompression stops; but it was a credit to @Thrutch that there wasn't any panic and he remained safe.

Keeping this account, though from his "understanding wife" would be the most intelligent course of behavior, aside from purchasing a torque wrench . . .

 

[L13]

This incident in Tahoe simply resulted from piss-poor quality control from the manufacturer, given its age and usage (just a few months, it was claimed); and something that has been brought up on a number of threads, over, sadly, a number of brands.

I don't see how you could possibly know this is true (or not true) based on the info from OP.

what seems to happen is the first stage gets "twisted" under pressure, and it is down hill from there...

Interesting. I was screwing around with a newbie diver friend recently and showing off my sidemount shotgunning skills. This reg spun 180° when I did that, something that hasn't happened before, but definitely seems like twisting under pressure.

This seems to hint at an alternate explanation, but is not very conclusive either.

 

[dlofting]

I dive DIN almost exclusively -- almost cannot recall the last time I attached a yoke, and have yet to loosen a properly-torqued valve stem, over thousands of dives.

This incident in Tahoe simply resulted from piss-poor quality control from the manufacturer, given its age and usage (just a few months, it was claimed); and something that has been brought up on a number of threads, over, sadly, a number of brands.

When I worked at a shop, years ago, there had been a time when regulators, across several major brands, were seldom ever torqued to specifications; and it was often the newbie's responsibility to ensure that that was taken care of -- one of the few drawbacks to online purchases, these days.

You never know.

I don't know whether I would have used that regulator with just a hand-tightened connection stem, especially after difficulty seating it -- on a dive which was likely to involve obligative decompression stops; but it was a credit to @Thrutch that there wasn't any panic and he remained safe.

Keeping this account, though from his "understanding wife" would be the most intelligent course of behavior, aside from purchasing a torque wrench . . .

I torque mine to spec every time I rebuild the 1st stage and the valve stem still comes loose occasionally.

 

[GJC]

Sounds like hand tightening was enough to prevent leaking initially but not enough after some movement that loosened the connection or temperature change may be a factor.

Cold, contracting metal parts, could be from air expansion as you inhale allowing a leak at the connection. When not used, metal returns to ambient temp and expands preventing the leak.

As mentioned above, root cause of your problem was either inadequate torque when the reg was assembled or twisting of regulator body when on a tank that loosened the connection.

 

[Robert H. Diver]

I torque mine to spec every time I rebuild the 1st stage and the valve stem still comes loose occasionally.

Red loctite and an impact is all you need

 

[Bigbella]

I don't see how you could possibly know this is true (or not true) based on the info from OP.

Well, let's see: a relatively new regulator -- characterized as only being "months old" -- whose connection stem had already come loose and required hand-tightening for it to even properly seat.

Many manufacturers call for a 30 nm (a bit over 22 foot pounds) torque setting on the connection or "valve stem" -- that is damn tight on soft brass if done properly; and in over four decades in the water, I have yet to experience any loosening issue of that nature.

If you're hand-tightening anything, aside from a DIN wheel, that is nowhere near specs.

Provided that @Thrutch wasn't futzing with it himself (and that doesn't appear to be the case, according to his account) -- it, in all likelihood, came from the factory in that condition, since there was no reason, it being new, to even have it serviced or mishandled by, say, a shop; and I have seen enough gaffes like that over the years -- new equipment, right out of the box, little set to specs -- to suggest that that could very well be the case . . .

 

[L13]

...Provided that @Thrutch wasn't futzing with it himself (and that doesn't appear to be the case, according to his account)...

Except he was futzing with it: specifically, rotating the regulator while under pressure (that was mentioned in a separate post, so you may not have noticed).

I torque mine to spec every time I rebuild the 1st stage and the valve stem still comes loose occasionally.

And here is a definite example of just such a thing happening on a properly torqued regulator, in a separate post he says this occurs when rotated on pressure.

I'm not saying your wrong. Just that you are jumping to conclusions, and exposing a bias.

 

[Thrutch]

Except he was futzing with it: specifically, rotating the regulator while under pressure (that was mentioned in a separate post, so you may not have noticed).

Fair, but I wouldn't call shotgunning a tank futzing with the regulator. If anything, this makes me wonder if the reg rotating in that fairly regular use case was the first indication it was coming loose.