Redundant Octos & 2nd Stages Unable to Deliver Air?

[SlugLife]

We helped her get the secondary as the October was not letting go!

Those Octobers, sometimes they can be warm and friendly, and sometimes they can be cold jerks with no warning. They are quite pretty and colorful though.

First stage failed closed with still 2500psi. left in tank.

I'm mostly focused on the main 2nd stage isn't usable, but octo still is. That's still a good data-point and similar principles apply to 2nd stages. Failing to maintain any component of the regulator could result in a failure.

But as indicated above, there is buddy breathing. But creates more of a task load.

...which in a rescue scenario, it's far less than ideal due to possible panic or other complications.

A positive scenario is when you are sick and required to blow chunks

Didn't think of that one! +1 for the Octo!

I suppose I could blow those chunks into my pony-regs. I shouldn't have to end the dive (due to lack of redundancy), so long as I didn't use too much air and am not too deep.

 

[rjack321]

A torn diaphragm or failed exhaust valve makes a second stage useless. Not something that would likely occur in the middle of a dive, but either one would do it.

Diaphragm came loose from the 2nd stage body in a necklaced backup once. Retaining ring had partly come unscrewed and pushing the purge dislodged the diaphragm. Wasn't ripped and could be fixed on the surface later and worked fine for years after.

Had the exact same thing happen in a BOV once, but in that case the diaphragm was misaligned at the factory and breathed wrong out of the box.

 

[rmssetc]

Diaphragm came loose from the 2nd stage body in a necklaced backup once. Retaining ring had partly come unscrewed and pushing the purge dislodged the diaphragm.

[NOTE: While I was on the dive when this happened,I did not witness all the details; my speculation will be in italics.]

During a casual, warm-water dive in Cozumel, a fairly inexperienced diver had a complete failure of his primary regulator at about 55'. He performed a CESA, without apparent injury.

The purge valve cover came off the regulator very suddenly. The failure mode was that 2nd stage was 'closed', not free-flowing.

After the incident, the diver reported that they couldn't get any air from the regulator. I saw the regulator very briefly -- the purge valve cover and diaphragm were gone. From a quick glance, at a few feet distance, there was no visible damage (cracked plastic, missing threads on the purge ring, etc). I think the regulator may have delivered air if the diver had manually depressed the demand lever.

To note -- the diver's buddy/buddies (group of 3) were not in close reach, and the diver did not attempt to switch to the octo (which worked) before surfacing.

The regulator worked fine (or without verbal complaint from the diver) during the previous dive.

I do not recall the regulator make & model.

 

[rjack321]

[NOTE: While I was on the dive when this happened,I did not witness all the details; my speculation will be in italics.]

During a casual, warm-water dive in Cozumel, a fairly inexperienced diver had a complete failure of his primary regulator at about 55'. He performed a CESA, without apparent injury.

The purge valve cover came off the regulator very suddenly. The failure mode was with that 2nd stage was 'closed', not free-flowing.

After the incident, the diver reported that they couldn't get any air from the regulator. I saw the regulator very briefly -- the purge valve cover and diaphragm were gone. From a quick glance, at a few feet distance, there was no visible damage (cracked plastic, missing threads on the purge ring, etc). I think the regulator may have delivered air if the diver had manually depressed the demand lever.

To note -- the diver's buddy/buddies (group of 3) were not in close reach, and the diver did not attempt to switch to the octo (which worked) before surfacing.

The regulator worked fine (or without verbal complaint from the diver) during the previous dive.

I do not recall the regulator make & model.

Actually I have seen this as well (had forgotten). Knock the plastic body hard and the diaphragm cover can pop off the threads. Was not me but an unsecured octo reg on a boat.

 

[Bigbella]

When I first began diving, I had been taught "buddy breathing" off of a single regulator -- and the common use of octopuses was still a few years off. That use of a single second stage, under emergency circumstances, happened only twice in over four decades. A 19 c.f. pony had been handed off on more than a few occasions; but I have yet to experience a regulator that would not deliver air, whether in freezing temperatures or otherwise.

I still typically carry rigs with two second stages, along with the aforementioned pony bottle, out of force of habit and demand of many dive fleets, which did come in handy when a drunken p**** in La Paz drove his Amigo (of all things) over dive gear to be loaded into a boat and destroyed a second stage.

A spare blind screw saved that day . . .

 

[rick00001967]

i just remembered another possible cause for an octo failure.....quite some time back there was a recall on some cheap braided hoses.
there were pics going around online showing the inside of the hose had deteriorated and the pieces that came off, blocked the intake on the 2nd stage.

 

[Tracy]

A torn diaphragm or failed exhaust valve makes a second stage useless. Not something that would likely occur in the middle of a dive, but either one would do it.

I really screwed myself with this post.
Cave diving today in Mexico. Dropped my stage at 1700 psi. We went out and did the rest of our dive without issue. Came back to the stages, did a gas switch and all was well. It was breathing funny, but still breathing. On a sharp inhale, I was getting bubbles out of the faceplate. Kept going and after about 5 minutes it started breathing wet. Then it started breathing really really wet to the point I could only breathe it by purging. Switched back on to backgas and exited without issue. Inspected it upon surfacing to find the faceplate was cocked on the threads and the diaphragm had come free. Must have dropped it too hard or kicked it funny when I made my drop.
So, as it turns out, it can happen.

 

[SlugLife]

I really screwed myself with this post.
Cave diving today in Mexico. Dropped my stage at 1700 psi. We went out and did the rest of our dive without issue. Came back to the stages, did a gas switch and all was well. It was breathing funny, but still breathing. On a sharp inhale, I was getting bubbles out of the faceplate. Kept going and after about 5 minutes it started breathing wet. Then it started breathing really really wet to the point I could only breathe it by purging. Switched back on to backgas and exited without issue. Inspected it upon surfacing to find the faceplate was cocked on the threads and the diaphragm had come free. Must have dropped it too hard or kicked it funny when I made my drop.
So, as it turns out, it can happen.
View attachment 818013

That's quite the coincidence! Sucks that it happened to you, but very relevant to the thread, and great to hear you're ok. (I would assume with cave-diving, there was plenty of redundancy)

speculating: The faceplate may have also been cross-threaded, and then bumping it caused it to dislodge enough to start breathing wet. My remote keyboard warrior guess is the regulator is probably fine, though I'd definitely inspect it closely, including the threads on both sides, and diaphragm.

I have seem some cave-divers, or at least Steven Martain from SideMounting.com carry an XS-Scuba star tool in his sidemount butt-pouch, for basic tasks like tightening hoses. While perhaps not necessary on your dive, one possible thing you could have done is swapped a 2nd stage from another tank underwater. Getting that extra gas back on a deco-dive or a cave-dive might be useful, so long as it doesn't get in the way of properly heading towards the exit. I'm just thinking through possible redundancies, even though I'm neither a cave diver nor do deco-dives.

 

[johndiver999]

You have collected a wide variety of ways a second stage can fail. Another thing I have seen is the housing of the second stage being damaged/cracked etc. and the damage is not obvious. One additional impact and it can shatter and fall apart. Of course the face plate can shift or fall off as shown above. Another possibility is the spring in the second stage fails also the nut that hold the demand lever can fall off or allow the demand lever to fall off (with some old designs)

Failure to assemble the second stage and or hose properly is not that unusual. Even a mouth piece falling off can start big problems if the person inhales water. Almost all these failures should be very rare and/or avoidable if zero errors are made in inspection, maintenance and assembly.

Regardless of the method of failure, a diver should be prepared for it.

I frequently dive with a few people who dive solo, with no redundancy, no octopus and below recreational depths, it makes me nervous to watch it. Hopefully they know how to breath from a purged and broken regulator and/or how to suck off the bc inflator.

 

[Tracy]

That's quite the coincidence! Sucks that it happened to you, but very relevant to the thread, and great to hear you're ok. (I would assume with cave-diving, there was plenty of redundancy)

speculating: The faceplate may have also been cross-threaded, and then bumping it caused it to dislodge enough to start breathing wet. My remote keyboard warrior guess is the regulator is probably fine, though I'd definitely inspect it closely, including the threads on both sides, and diaphragm.

I have seem some cave-divers, or at least Steven Martain from SideMounting.com carry an XS-Scuba star tool in his sidemount butt-pouch, for basic tasks like tightening hoses. While perhaps not necessary on your dive, one possible thing you could have done is swapped a 2nd stage from another tank underwater. Getting that extra gas back on a deco-dive or a cave-dive might be useful, so long as it doesn't get in the way of properly heading towards the exit. I'm just thinking through possible redundancies, even though I'm neither a cave diver nor do deco-dives.

No safety issue. I could have taken it apart and figured it out and fixed it underwater, but there wasn't a reason for it. I had plenty of backgas left to make the exit plus my wife's backgas usually has a ton left.
It was just odd coincidental timing.
It wasn't cross threaded, it has been working great every day for two weeks. It probably just got smashed a bit when I dropped the tank.