Regulator failure on a solo deco dive

[rob.mwpropane]

You just need to be careful doing that. I sometimes think that the main reason these things get loose in the first place... using the first stage as a lever to take it off the tank.

And ya, 45 seconds is right. I said 5 minutes to allow time to track the Allen key down... ;-)

Yeah.. agreed. Again I don't apply force enough to turn, it's more of a feeling knowing what's loose... heck just seeing the hoses push on it if it moves at all it's loose. Anyone who is mechanically inclined does this all the time in life.

I've had them come a little loose before.. just being careful not to turn things has alleviated 95% of those issues. It's more of an unconscious action then a conscious one when gearing up.

 

[Bigbella]

Furthermore.. why can't we agree on a set torque? Is it common to just convert from in lbs, to ft lbs, to nm and back again? Honest question? Or is it just because there are different torque wrenches?

I exclusively use Nm, in terms of measurement, because that was what I had originally learned in school, and all of my torque wrenches are German and metric . . .

 

[Bigbella]

Not that this is specifically on topic, but the removal of oring with detal pick is what I have seen used and don't trust it being used. Could a thin piece of flat plastic (maybe expired credit card) be used. Try slipping underneath oring to the pry oring out. On some use of orings I found just using fingers to pinch (scrunch) to get a grab hold to remove the oring. Just thinking.

Yeah, an old credit card or one of those disposable plastic dental picks are awfully useful; so too plastic pick sets, especially made for the removal of o-rings.

I also have a couple of stainless steel removers with tiny balls at each end, rather than hooks . . .

 

[Bigbella]

I hope my inexperience and lack of knowledge doesn't have me sighting the wrong parts. Here's direct from the manual.

Furthermore.. why can't we agree on a set torque? Is it common to just convert from in lbs, to ft lbs, to nm and back again? Honest question? Or is it just because there are different torque wrenches?

I bought what I needed to rebuild my personal regs. I'm sure I could work on a lot of other ones with what I have but I like only having one set of rebuild kits, and one "model" to work on so to speak.

I just noticed that there was a figure, on that larger manual page, for tightening the "DIN housing" to 230 in/lbs which works out to be almost 26 Nm, within a normal range for regulator settings; and that that lower setting was for the "DIN retainer" which is probably just the small piece of threaded hardware that keeps the sintered filter in place?

That may also be the source of confusion, not just imperial versus metric measurements, but the occasional inconsistency of parts names between brands -- the "DIN housing," being a "connection stem" and the "DIN retainer" just a "locking screw" in my manual . . .

 

[rob.mwpropane]

I noticed that there was a figure, on that manual page, for tightening the "DIN housing" to 230 in/lbs which works out to be almost 26 Nm, within a normal range for regulator settings; and that the lower setting was for the "DIN retainer" which is probably just the small piece of threaded hardware that keeps the sintered filter in place?

That may also be the source of confusion, not just measurements, but the occasional inconsistency of parts names between brands . . . .

That's why I posted it. I think you can get 5 different manuals that site 3 different names for the same part.

Either way I think the manual is correct.

 

[rsingler]

What @Bigbella said...
With due respect to the many contributors to this thread, it would seem that only the OP and one or two others have looked at the schematic before weighing in. We have an apples and oranges problem here.
Some of you discussing large torque values are referencing a different part of the regulator than what appears to have loosened in this Signature. Yes, the DIN bolt, or the DIN Housing (as it is called in the Signature) is torqued to 20-30 ft-lb. Yes, this part can loosen if the tank is picked up by the first stage when pressurized.
But it's not the part the OP referred to in post #1: "the bit that takes an allen key and holds the DIN o-ring."
That part, called in the Signature the DIN Retainer, has a completely different function, which is to merely keep the DIN wheel from falling off and to hold the main sealing o-
ring for the tank valve. Its torque is indeed only 80 in-lb, because it is under minimal load. Specifically, it is less than the DIN Housing to keep from inadvertently loosening the critical connection to the reg body when corrosion under the wheel is cleaned, for example.
If I were to guess along with the rest of you regarding a cause, I would suggest that the likely cause is thread lubrication. On page 11, the manual specifically warns against lubrication except where specified.
Here's what happens: lubrication seems logical, because you know that salt water is going to percolate along the threads and corrode, and you want disassembly to be possible at the next service. Unfortunately, torquing to spec with added lube that was not engineered into the design increases thread load by as much as 150%. And when the lube is inevitably squeezed out from between two adjacent threads over a two-year service interval, that increased axial load may make it impossible to separate the components without damage.
Conversely, given the lack of use of torque wrenches by many shops, AND lubing threads indiscriminantly and excessively, many newly-lubed fittings are very easy to loosen.
It is a sad state of affairs when it was too much trouble for the OP's shop to download the manual (after all, it looked like a Hog!) and follow the directions, instead of going to 15 ft-lb, which is too little for a DIN bolt, and too much for the DIN Retainer.

 

[Bigbella]

It is a sad state of affairs when it was too much trouble for the OP's shop to download the manual (after all, it looked like a Hog!) and follow the directions, instead of going to 15 ft-lb, which is too little for a DIN bolt, and too much for the DIN Retainer.

@rsingler, to the rescue!

+1 on the "sad state of affairs" . . .

 

[Thrutch]

If I were to guess along with the rest of you regarding a cause, I would suggest that the likely cause is thread lubrication. On page 11, the manual specifically warns against lubrication except where specified.

Thanks for the great info. Would it have come from Deep 6 lubed? This reg is only six months old.

 

[rsingler]

Unlikely. Inadequate factory torque is a possibility. I see it everywhere, even the big boys. My Scubapro Mk19EVO arrived with a barely tight DIN bolt. I easily unscrewed it by hand.

But any time a generic tech gets hold of a reg, the urge to add a touch of lube "because the disassembly was so hard" is almost overwhelming. I was guilty of the same thing for a decade until I learned the physics. It's really hard to send a reg into salt water knowing the threads "have no protection".

Regs with an oring seal above the DIN bolt threads are rare these days. Interestingly, the old Poseidons had one, but not the new XStream. Go figure. Same with the old Mk5.

All my regs get a yearly yoke or DIN bolt removal/cleaning/reassembly, even if they have a 3-year service interval. I just leave the rest of the reg alone.