Poseidon Regulator Reliability…

[Bigbella]

@Tracy, so inline with what Bigbella said - should a shut-off valve not solve the problem for the upstream regs, too?

It was never an issue with the Jetstreams with their switches off — or the Xstreams either, provided that they’re well-tuned. We never closed the valves with ponies, stage or deco bottles, in the first place; and there was never any issue over more than four decades; but I do realize that that practice is verboten by the GUE folks — so too, co-called upstream regs, for that matter.

I typically soak my pressurized equipment on a pony, etc, for hours on end, and there has never been any loss of gas . . .

 

[jborg]

I'm slightly skeptical of a purged Xstream/Jetstream second resulting in a flooded first stage during valve drills, to be honest. The natural state of the rubber valve insert is closed, it opens up due to gas pressure until the servo valve seals... Also, the second stages tend to be below the first stages while in any sort of horisontal trim. So water would need to force itself past the valve insert and flow upwards into the first stage...

I'm sure it can happen in a suitably convoluted situation, but I doubt it's a problem in practice. At least, less of a problem than it being a major pain in the ass to do full a valve drill with these second stages to begin with, given all the freeflowing going on when you open the valves.

 

[Bigbella]

Slam opening was probably a poor choice of phrase. I can always rely on @Tanks A Lot for an erudite discussion.
We are not at odds, and the statement buried late in my comment stands:

If you were taught to take 3 minutes to open a 100% O2 tank, as one conservative CCR Instructor opined, you will be unhappy with a Jetstream or Xstream.
What is probably needed is a demo video. Perhaps someone will help us out. The valve will likely not seal until the dynamic IP exceeds 70 psi, because the servo is venting faster than the servo compartment is filling via that sintered flow restriction, when the IP is still that low. So get past 70 psi within however many seconds you can tolerate venting that oxygen.

No big whoop . . .

 

[Tracy]

@Tracy, so inline with what Bigbella said - should a shut-off valve not solve the problem for the upstream regs, too?

It would, but why? Literally any other reg on the market would be a better choice for a deco bottle. Why would you intentionally choose the one that does it worst and then add things to make it almost as good as everything else?

Just use them for backgas, that is where they excel.

 

[Bigbella]

It would, but why? Literally any other reg on the market would be a better choice for a deco bottle. Why would you intentionally choose the one that does it worst and then add things to make it almost as good as everything else?

Well, you used what you had on hand — and we had Poseidon in spades, back then; and they never once posed a problem, even under the harshest of conditions . . .

 

[Frogman82]

No big whoop . . .

My xstreams vent a bit more gas than that. But I found that if they are not tuned correctly/cracking pressure to high they vent less gas. Dont know why. Not saying your ones are badly tuned, just my subjective observation.

 

[mr_v]

It would, but why? Literally any other reg on the market would be a better choice for a deco bottle. Why would you intentionally choose the one that does it worst and then add things to make it almost as good as everything else?

Just use them for backgas, that is where they excel.

Oh yeah, I totally get it. I am wondering about the options in case if I am in a bend and need one for a deco bottle

 

[Bigbella]

My xstreams vent a bit more gas than that. But I found that if they are not tuned correctly/cracking pressure to high they vent less gas. Dont know why. Not saying your ones are badly tuned, just my subjective observation.

My regulators -- Cyklons, Jetstreams, Xstreams -- are all set to the far lower end of cracking effort (Poseidon allows for a generous 0-100 mm w.c. range; and one of their poorly translated manuals mentioned, "Above 40 mm w.c. the breath doesn't feel good" -- yikes!), with none, that I recall, over 30 mm w.c. — closer to 25 mm, for effortless breathing and a concomitant risk of free-flow, similar to that of the Jetstream PP, the positive pressure model in the Atmosphere full face mask (which, interestingly enough, possesses Xstream second stage guts); and which I came to prefer.

Below is one of the full face masks, being pressurized. Had the switch on the Jetstream been set to “+” it would almost imperceptibly free-flow . . .

 

[Frogman82]

My regulators are all set to the far lower end of cracking effort (Poseidon still allows for a generous 25-40 mm w.c. range!), with none over 30 mm w.c. — most closer to 25 mm, for effortless breathing and a concomitant risk of free-flow, similar to that of the Jetstream PP, the model in the Atmosphere full face mask (which, interestingly enough, possesses Xstream second stage guts), which I came to prefer.

Below is one of the full face masks, being pressurized. Had the switch on the Jetstream been set to “+” it would almost imperceptibly free-flow . . .

I set mine to 35-40 mm.wc. I find that they are very sensitive when tightening the set screw after adjustment. I snug it up ever so lightly or it throws the adjustment off. Just out of curiosity, do you know why the regulator vents less gas the higher the cracking pressure?

 

[TheCatFish]

I set mine to 35-40 mm.wc. I find that they are very sensitive when tightening the set screw after adjustment. I snug it up ever so lightly or it throws the adjustment off. Just out of curiosity, do you know why the regulator vents less gas the higher the cracking pressure?

I can't offer a very precise answer, but I assume that whatever parts are being adjusted when the the crack pressure is tuned high, causes the servo and membrane to contain more pressure during the initial pressurization of the system.

Containing that pressure means that the system doesn't need as long to reach threshold pressure before the membrane in the secondstage seals.

If the second stage cracks more easily, then it would take slightly longer for the pressure in the system to reach the critical pressure for sealing to happen, since the membrane would be allowed to leak out some more of that pressure until enough has built up to overcome the threshold and create the seal.

In my experience though this time difference is fractions of a second unless you are dealing with some very very dramatic crack pressure adjustments. Hopefully someone with some more engineering experience and education can explain the mechanics a bit better.