Stage/deco/BO reg with inline shutoff

[stuartv]

I’m pretty opposed to them, especially on bailout bottles. If you want a nice rant, Dave Slutton wrote a great one in one of the CCRX FB discussion groups.

I’d wager/I fear your instructor was taught by Sotis, one of the few former rogue proponents of such things. Happy to be mistaken on that.

Also, that name was ringing a bell and it finally clicked. I don't want to get into "what I've heard" or, for that matter, what I've seen/read with my own eyes. So, I'll just say that I would give more weight to a rant on inline shutoffs if it came from someone else.

My instructor and his instructor are not Peter Sotis, nor taught by Sotis. Nor do they dive rEvos.

 

[grantctobin]

Good question. If you do the prescribed maintenance on one of the expensive XS Scuba/Highlands ones, like you do the maintenance on your deco regs (which you DO do, right?), what problems are you likely to have?

I switched on my O2 CCR reg only a year ago (because the default ones don't hold back >150-165psi) and it hasn't seen salt water. I suspect the black cap isn't water tight and is likely to hold water. If you dive in salt water often, I'd actually consider soaking and drying the regs in fresh water pressurized but with this black cap off.

 

[rjack321]

Just curious, not trying to be contrary, when you say "suck", in which way do they 'suck'?
Thanks.

The functional part is basically a pinhead sized piece of nylon under a spring with no backing or metallic support. It's exposed to just about every environmental insult in the ocean. It absorbs water, loses water, bakes in the sun, freezes, etc. They fail, they fail often and your entire gas supply is riding on that pinhead of nylon. You don't want to have it if its at all possible to avoid using one.

 

[johndiver999]

I'm not a tech diver, but it sounds like a gear solution to a skills problem. Open the valve slowly, if bubbles appear, turn off, check/tighten the Din connection and move forward. I have seen one fail catastrophically on the boat.

 

[rjack321]

What's this all about

World's biggest serial diving liar

 

[rjack321]

It does happen that people sometimes go to remove a DIN 1st stage from a tank and can't get the DIN wheel to turn, so they twist the regulator itself, which turns the wheel along with it. Then, they hold the wheel and twist the reg back, then turn it again. I.e. they basically use the 1st stage body to ratchet the DIN wheel until it's open enough to turn by hand.

Now, I KNOW that you shouldn't do that. It's a good way to actually loosen the bolt in the center that is holding the DIN threaded part of the reg on.

But, it seems like it would be possible to accidentally get that same kind of ratcheting action by accident that could loosen the DIN wheel (on a depressurized line) enough to allow the O-ring to extrude. Very unlikely, I'm sure. But, would it ever happen?

I'm not trying to disagree or argue with you. Just understand what you think is possible versus "NEVER have to worry about that happening."

It SOUNDS like the reality is that, yes, with no inline shutoff, you COULD have happen exactly what happened to the student that I described. But, (from what you're saying), that should never be any worse of a problem than it was that day. I.e. see the bubbles starting to come out and shut the valve, tighten the DIN wheel a little bit, and re-open the valve. Worst case is not bad at all, in which case it's not enough of a risk to merit all the other cons of an inline shutoff. Yes?

How contrived are you going to get? You went from bumping the reg and having it depressurize, then the handwheel turning 1/64th of a rotation (5 degrees) to the point of the oring leaking. Now you are actively unscrewing it with some sort of mysterious ratchetting action which you are making up from whole cloth.

Show me an accident case of an extruded DIN oring that couldn't be reseated, lead to a failed deco bottle, that then couldn't be compensated for with another gas source, or swapping regs, and then we'll talk. This doesn't happen. You are adding failure points to address a mythical problem.

 

[Wibble]

Implied but not explicitly mentioned: IP pressure will increase beyond safe limits, e.g. a 90m dive will double the nominal IP at the shutoff valve & first stage (hence OPVs). Probably only an issue with deep dives.

Couple of pros:
Properly shut off when scootering.
Another way of ensuring shutoff if gas is really critical such as long penetrations (arguably not).


Maybe it’s just easier to give the first stage a validation twist before powering on?

 

[happy-diver]

World's biggest serial diving liar

and yet he has contributed more than most


Diver Daves Rebreather Site

 

[rjack321]

and yet he has contributed more than most


Diver Daves Rebreather Site

Believe whatever you want.

Dave Slutton: Pilot, diver, pathologial fraud? An analysis of one of the most fascinating people ever.

 

[happy-diver]

Exactly!

Diver Daves Rebreather Site

Vehement distaste for Dave doesn't negate his contribution

What I have found, is that those that speak poorly of Sutton
are far more like him, than they would ever choose to think
or they are only following all the villagers up that steep hill


He tells me that link of yours was fashioned by a friend, that is difficult to believe