Upstream regulators and DIR

[nessmiller]

Folks,
I tried asking a similar question in the equipment/regulator forum that I probably should have asked here.
Anyway, I now have a better understanding of "upstream" regulator design and its failure modes. Given this, my question is whether upstream regulators should not be used in tech diving or are they just not "DIR" blessed? If it is the latter, is it due to the failure modes, hose-overpressure device, or both?
Thanks for the insight.

 

[salty]

the failure mode of a device should be "safe" in any pice of machinery. It is far safer to have a reg fail "open" and deliver gas than it is to fail shut and cut you off. The selling point of Posidens is that they are such good breathers at depth. Well if your deep enough that your reg is strugling to deliver good flow than you should have some HE in the mix to thin it out. This is an an added advantage above that of the required END for a deep dive. Keeping this in mind the posiden has nothing to offer excypt a dangerous failure mode. Now befor the flames start let me state that the only time I have experenced posidenn regs that failed is when people who shouldent be poking around in there regs go and mess something up but then any reg that is maintained should be relativly safe(10 years of diving the same regs and no problems yet) . But why take the chance, that is one of the main points of DIR gear choices and I would think any good tec diver. If there even a remote chance one pice of gear may fail over another the choice on which one to bring on a dive is easy after all its your life your betting.

 

[BCS]

Hi! It sounds as if the upstream failure mode has been covered, but as to DIR, I did not see any mention of the fact that upstream regulators require custom (unique) second stage hoses with over pressure relief integrated into them. This keeps the second stage hose from exploding when the IP increases. These hoses are expensive, non-standard, more complex, and ill advised.
Why not use a reg that has a failure mode that does not shut down air supply, as well as a reg that does not require bastard hoses? These simple choices make for more confidence in your equipment (which means less worry underwater) and less (if any) dives cancelled for equipment reasons because standard hoses can be found everywhere, Poseidon hoses cannot.
So, to answer your question, they are not "DIR blessed" because of both the closed seat failure mode as well as the unique hose requirement.

 

[WreckWriter]

I believe the over-pressure relief valve is built into the first stage, not the hose. Am I wrong?

Tom

 

[BCS]

Second stage hose Tom.

 

[BCS]

Tom,
You are correct that there is a "safety valve" (as Poseidon terms it) in the first stage. The second stage hose also has an OP relief built into it as well.
Sorry, I didn't catch what you were talking about immediately. I haven't serviced any Poseidon's in a couple years and have gotten rusty.