Deep dive and user adjustment knob

[Colliam7]

Has anyone had an issue while deep diving (95 feet) where their second stages began to free flow and they need to dial the user adjustment knob back (clockwise)? Per most manufacturers this adjustment may be needed in current or while inverted, but it seems to me a probable need at depth due to higher water density vs ambient pressure in the second stage. Thanks for reading.

Interesting question, and discussion.

I have never had such a problem with any of my regs at depth. Like Burhan, I usually open the UAB control fully at the start of the dive, put the venturi control in the 'Dive' position, and don't touch it again during the dive.

 

[Jack Hammer]

@dandecraene, Hey Dan, I dont recall any regs freeflowing at those depths with the adjustment wide open. I have seen occasional weepage and some free flowing from fast scootering against heavy flow. That's been minimal though.

 

[dandecraene]

Thanks everyone, for the input. I guess “seep” would have been a better description. The reg was tuned very loose with a 0.9 inches of water cracking pressure. An adjustment to 1.2 seems to have corrected the issue with no real noticeable difference in breathing ability.

 

[Angelo Farina]

Thanks everyone, for the input. I guess “seep” would have been a better description. The reg was tuned very loose with a 0.9 inches of water cracking pressure. An adjustment to 1.2 seems to have corrected the issue with no real noticeable difference in breathing ability.

Still we are curious! Which reg was it?

 

[John C. Ratliff]

Thanks everyone, for the input. I guess “seep” would have been a better description. The reg was tuned very loose with a 0.9 inches of water cracking pressure. An adjustment to 1.2 seems to have corrected the issue with no real noticeable difference in breathing ability.

There is one other factor no one has mentioned, and that has to do with the design of most second stages. In most second stages, the exhalation valve is not on the diaphragm, but rather located a short distance below it in the exhaust "T." In certain positions, this places the part of the exhaust mushroom about an inch above the center of the second stage LP diaphragm. If the second stage I see set to a cracking pressure of p, say 0.9 inches of water pressure or less, it will leak air simply due to this difference in position. The position many divers using BCDs to be completely neutral in the water is completely horizontal with the head down, whicjph will result is this pressure differential due simply to positioning.

SeaRat

 

[D_Fresh]

I've never experienced any issues of free flow with my AL Core or Titan regs, even at 35m while inverted. So far, no issues with current causing unintended purging yet either, but I'm not doing a lot of ripping current dives in PH. I just open 'er up and don't touch it until I forget to turn it off at the surface, spit my reg out, and it splashes purge down causing a brief free flow LOL. I would say they're both tuned pretty close to the "edge of FF", they breathe like a dream, but no issues....

 

[Subcooled]

I have only Apeks regs (DS4/DST and XTX50) and I've done dives to 45m or 150ft and I have never experienced any free flows or air leaks caused by depth.
There is an adjustment knob on the reg and I turned it all the way down. There is also a venturi lever (+ or -) and I chose "-".
And I adjusted the IP from 10 bar to 8.5 bar.
I made these changes almost a decade ago, once and for all.

The regs are working reliably.
Breathing feels normal but different from breathing on the surface of course.

Air leaks are not acceptable at all.

 

[BoltSnap]

here is an adjustment knob on the reg and I turned it all the way down. There is also a venturi lever (+ or -) and I chose "-".
And I adjusted the IP from 10 bar to 8.5 bar.

If you make these changes that make the regulator breathe more difficult in every aspect, of course you won't get any leaks but it'll breathe like sh1t!

Regulators with cracking pressure adjustment are made to be used with the knob turned all the way out, easiest breathing/lowest cracking pressure without leaks, and with the venturi turned to the "on" position when the regulator second stage is in your mouth.

You are the first person I know that wants their regulator to breathe like crap down at 45m. VERY strange and not the proper way to use your regulator. WHY????

 

[Subcooled]

If you make these changes that make the regulator breathe more difficult in every aspect, of course you won't get any leaks but it'll breathe like sh1t!

You are completely right!

I prefer a reg that breathes like sh** over one that starts free-flowing.

When I learned to dive I was taught to breathe slowly and deeply and my regs got adjusted for ice diving and while they are "a little bit" hard to breathe, I got used to that.

You are the first person I know that wants their regulator to breathe like crap down at 45m. VERY strange and not the proper way to use your regulator. WHY????

+2C or 36F water and an overhead environment (some people say that water never gets colder than 39F but apparently it does, and in the sea just below the ice I've recored 30F which is pretty cold). The moisture in exhaled air then becomes a major pain.

When I am at depth, then I do not want air leaks either. I prefer a known hardship over something that surprises me and forces me to resort to instantaneous emergency procedures. I do know that this preference may be a little bit "special", and not suitable as a model for most people

 

[Ben_3]

Interesting thread. I had an issue just the other day, down at 85 ft after 10 min my reg free-flowed and we had to immediately end the dive. I think something might have froze up but i'v seen colder without issues.. My venturi lever was in the + position and tried everything underwater (Apexs XL4). Will be getting the set looked at asap.