Diaphragm 1st stages blowing out at depth?

[Tassi Devil Diver]

I have heard and seen an environmental seal blow on a Hog first stage at 60m (200ft), underwater it sound like a shot gun going off followed by the diver being engulfed in a mass of bubbles.

The reg was self serviced, it was rebuilt that evening for diving the next day.

I have also seen the environmental seal on a Hog reg balloon out quite a bit.

 

[rhwestfall]

if it isn't serviced, or serviced poorly, anything can happen.....

 

[richmonddiver]

In another thread, there was a video posted about a 1st stage that blew the diaphragm out at 180’.
I’m pretty sure in was the diaphragm because when the guy got back to the boat they turned the air on and air blew out the HP adjustment hex hole and the only thing in there that could blow would be the diaphragm. IIRC the reg was a Zeagle Flat Head.
So, my question is:
How often does this happen, how does this happen, and what could have gone wrong in the reg internally that could expose the diaphragm to full tank pressure that rapidly that a second stage didn’t even have time to freeflow. Or in that case would a second stage freeflow at all if all the air pressure was escaping through a torn diaphragm?
Maybe there’s a knowledgable reg tech out there that could explain how or why this could happen.
This seems kind of freaky to me. I’m starting to wonder just how vulnerable diaphragm regs really are. I had a buddy years ago who did a tech dive in Monterey. He had completed a 200 ft dive and was in deco at 60’ when all of a sudden one of his backgas second stages let loose and freeflowed wildly. This led to a whole chain of events, but long story short he was fine. When they checked the IP later on his Apeks 1st stage it had soared to over 270 psi. It was at 135 before the dive. This of course could have been an HP seat gone bad or a defect?

Are pistons vulnerable to anything like this? Other than possible squeezing out an O-ring or something? I have several pistons and they are my go to regs.
Now I’m starting to look at my Conshelfs with suspicion, or am I being silly?

Here's the the diver's narrative from another chatboard
Zeagle Regulator Blows at 180 ft - Spearboard.com - The World's Largest Spearfishing Diving Boating Social Media Forum

 

[CWK]

Here's the the diver's narrative from another chatboard
Zeagle Regulator Blows at 180 ft - Spearboard.com - The World's Largest Spearfishing Diving Boating Social Media Forum

Thanks . Most interesting.

 

[Centrals]

I find it very odd when diver refused to have the 1st stage serviced when the environmental seal was bulging greatly.

 

[Eric Sedletzky]

Here's the the diver's narrative from another chatboard
Zeagle Regulator Blows at 180 ft - Spearboard.com - The World's Largest Spearfishing Diving Boating Social Media Forum

Sounds like Jim wasn’t the only one to have a Zeagle diaphragm reg blow. I’m still mighty curious as to why it blew out the diaphragm when he said the rest of it looked fine inside?
I know nothing about Zeagle regulators or how they are designed.
My wildest guess would be that it was not put together correctly, or a soft part was defective, or a soft part was made from the wrong material.
So I guess the best backup to use if you are going to use Zeagle regs on your main is a MK2/R195 on a 30 cf pony?
I think I would probably trust the MK2 to any depth before I’d trust the Zeagle in a pool!

 

[Pao]

I have heard and seen an environmental seal blow on a Hog first stage at 60m (200ft), underwater it sound like a shot gun going off followed by the diver being engulfed in a mass of bubbles.

The reg was self serviced, it was rebuilt that evening for diving the next day.

I have also seen the environmental seal on a Hog reg balloon out quite a bit.

HOG's and other DST clones use a transparent plastic washer between the diaphragm and diaphragm clamp which the original Apeks ones do not use. Omitting this part can cause the main diaphragm to leak or even blow.

 

[blatter]

The most likely possible causes would be incorrect servicing: reusing a diaphram, incorrect assembly - particulary not tightening the diaphram retaining ring properly, incorrect order of assembly or using the wrong part. Diaphrams on modern reg first stages are supposed to be replaced every time they are removed and specified assembly instructions need to be followed as per the service manual.

I have seen a friend's Zeagle first stage that had just been serviced by a dive shop with its retaining ring not adequatly tightened - a disaster waiting to happen - serviced by an idiot. Service manuals for this type of reg often not only give a torque setting for the retaining ring but state that there should be metal to metal contact between the ring and reg body, or words to that effect. These failure points are common to all modern diaphram first stages that I am familiar with. Have been using Zeagle regs since they stopped selling rebadged Apeks. In my view the first stages are even nicer than Apeks, which I have been using for around 20 years. I recently serviced one of my Zeagle first stages after it had done more than 600 dives (over 8 years of diving in salt water). I didn't service it at the recommended service intervals because I was curious to see how it would go (I dive with redundent gas supply when necessary). It was still working fine when it was serviced and the internals looked as good as new after minimal cleaning and it still works as good as new.

I would be interested if the failure reported by the OP was due to a material failure of the diaphram rather than one of the causes I have just outlined. That would be very concerning.

On a related issue, some old diaphram regs (such as at least some of the Dacor models) used a push rod made of relatively soft rolled steel which was prone to corrosion and bending. Failure of that pin will immediatley stop gas air flow. Very bad design in my view. The more modern diaphram regs that I have seen from Aqualung, Hog, DiveRite, Zeagle, Apeks etc all have a solid and strong stainless steel push rod that should never fail in this way and in my experience are very reliable. A US Divers Conshelf I now use to drive a booster pump still works OK and hasn't been serviced for 28 years, although I would service it if I ever used it for diving. I have done thousands of dives using Zeagle regulators, one first stage has done over 900 dives, and never had any problems at all.

 

[victorzamora]

@tbone1004 had this happen to him in his cave training. He claims he even had a little "donut" shaped piece of diaphragm left over from where the environmental seal cap held the edges down but the central part blew out. Apparently, the reg exploded forcefully enough to disorient his instructor for a couple of seconds.

 

[tbone1004]

@tbone1004 had this happen to him in his cave training. He claims he even had a little "donut" shaped piece of diaphragm left over from where the environmental seal cap held the edges down but the central part blew out.

donut was from the environmental seal not the diaphragm. Paul found the "donut hole" that blew out a couple days later when we were in that area of the cave again. Bright red silicone sticks out easily on the bottom of a cave. I now check my IP before each trip....