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DumpsterDiver emergency ascent from 180'

Discussion in 'Advanced Scuba' started by 2airishuman, Aug 9, 2017.

  1. stuartv

    stuartv Seeking the Light ScubaBoard Supporter

    # of Dives: 200 - 499
    Location: Lexington, SC
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    Yes. I have refrained from casting judgment on DD and I am glad I did. I still wouldn't do that dive myself. But, after reading what he has posted over there, in particular what things he might do differently in the future, I am even more sad that he isn't able to participate here. It seemed to me that he could take the experience as a learning opportunity or he could take it as a confirmation that what he was doing was perfectly fine. It seems like he's taking it as a learning opportunity and that is great to see.
     
  2. 2airishuman

    2airishuman Solo Diver

    # of Dives: 100 - 199
    Location: Greater Minnesota
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    I think that some of the discussion there may be mistaken. It was the failure of the main diaphragm that led to catastrophic loss of gas. The environmental seal was destroyed as an effect of the failure of the main diaphragm. I believe it is likely that the failure of the environmental seal may have been what made the loud noise, though.

    Question then is why the main diaphragm failed, with much speculation that it pulled away from the housing around the edges due to reuse of non-reusable parts. I've never had a Zeagle apart, but on the Hog D1 and the Conshelf XIV, you get a leak, not an explosion, because the pressure plate on the spring is sufficient to hold the diaphragm in place. I can't imagine that the Zeagle is much different. Overpressure from e.g. an HP seat leak doesn't seem to fit the facts because the 2nd stages would have freeflowed before the diaphragm blew. I would be more inclined the believe that the diaphragm got a tear in it somehow, perhaps as the result of the wrong parts being used or the parts being assembled in the wrong order.

    You are correct. They are fashionable but contribute little to dive safety. My regs have them on the theory that they help prevent formation of ice on the main spring in cold water. I'm skeptical that they make much of a difference but am not sufficiently confident of my skepticism to dive without them.
     
    gfaith likes this.
  3. snowdog61

    snowdog61 Solo Diver

    # of Dives: 500 - 999
    Location: Florida's East Coast
    869
    558
    I just didn't feel 100% about posting a link to another site's forum here on SB. edit - guess I was fine as a SB staff member linked it up

    No - the environmental seal isn't meant to seal the HP side of the reg - that job goes to the HP seat. The diaphragm that blew is a rubber/fiber composite (very tough) which isolates the IP from ambient but is acted on by a balancing reaction spring (isolated but reacting directly upon the diaphragm). The environmental seal transmits ambient conditions to assist the diaphragm in depth compensation. That seal gets installed after setting your IP so doesn't (or shouldn't) see much pressure. Once you remove tank pressure, it should depress (concave) but return to 'normal' once pressure is applied to the reg if correctly installed. A bulging one is no bueno. The diaphragm should not see any more pressure than IP + whatever depth compensation is being applied via the environmental seal. For whatever reason, the diaphragm on DD's DSV let go. The tank pressure was no longer regulated so it took the environmental seal with it.
     
    Last edited: Aug 18, 2017
  4. gfaith

    gfaith Solo Diver

    # of Dives: 100 - 199
    Location: Desert SE of NM
    444
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    I would have to agree with Zairishuman. The main diaphragm failed. Why is the question.. I have a Hog D3 that is only for warm water usage and doesn't have the sealed protection. Yes, I wished I had made a different purchase but there are even kits to add that external diaphragm to the D3.
     
  5. Colliam7

    Colliam7 Tech Instructor Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Kents Store, VA
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    Stuart,

    I may need to re-read the posts in that thread. But, it was my impression from DD that the problem was a ruptured main diaphragm. Capt. Gene made reference to the environmental seal diaphragm several times. But, a ruptured environmental seal should not produce such a problem. And, Gene later clarified his reference.

    Instead, I believe that the main diaphragm failed, and that caused the rapid air loss (as it should). The discussion in the spearboard thread seemed to focus on how recently the first stage had been serviced, and whether service parts were re-used (always a no-no). I happen to specifically service Zeagle regulators (in fact, am working on a couple right now). And, I have not seen a ruptured main diaphragm in any regulator with a 'new'' diaphragm - i.e. a diaphragm operating within its nominal 'useful life' of 1 year. In fact, I have used Zeagle first stages for 3 years between servicing without problems. (Of course, I must add a caveat: as Rob said earlier in the thread, just because you get away with something, doesn't make it a good idea!' :))

    A more likely scenario, from my perspective: when the first stage was previously 'serviced' - before DD bought it - the diaphragm may have been re-used, or an incorrect diaphragm was used (i.e. other than Zeagle - Zeagle distributes a 'First Stage Service Kit", P/N 345-1000 that covers all of their regs, at least all that I have encountered, and includes a new diaphragm). Or, although the previous owner said it was serviced about 2 years before DD bought it, the actual interval was considerably longer. Another possibility is that the regulator was stored in extraordinary conditions - in particular hot conditions where the diaphragm material deteriorated. I have no data on the rate of deterioration of the diaphragm material under adverse conditions such as heat, so that comment is merely speculation.
     
    Last edited: Aug 18, 2017
  6. northernone

    northernone Contributor Rest in Peace ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Currently: Cozumel, from Canada
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    Thank you for the heads up. I love honest discussion.
     
  7. snowdog61

    snowdog61 Solo Diver

    # of Dives: 500 - 999
    Location: Florida's East Coast
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    I have serviced Zeagles and they are similar in design to all the other diaphragm types. The big advantage to having the environmental seal is that the depth compensation is isolated from the main spring/diaphragm area. It is dry sealed so no shmoo to pack and the insides stay as clean as the day you rebuild it. My non-sealed Flathead LT tends to hold the saltwater/rinse water in the IP adjustment hole and isn't so pristine at rebuild. Rupturing an environmental seal doesn't do anything more than letting water in. Depth compensation is now direct on the diaphragm rather than transmitted via the seal & link. DDs diaphragm let go - the question is why
     
    Colliam7 likes this.
  8. Bryan@Vintage Double Hose

    Bryan@Vintage Double Hose Instructor, Scuba

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    I won't speculate on what happened to the regulator in the discussion as I have no 1st hand knowledge of it.... But I do have decades of experience with high pressure diaphragms in regulator first stages. They are layered with a corded center (similar to a tire) thickness varies between manufactures and discussion /opinion on the thickness/performance/durability of such is exhausting.
    Failure is extremely rare but not impossible. In my OPINION the way it can/could occur is by age, re-using one, improperly torque, greasing the rim where it meets the friction washer or a combination of all of them.
    Environment has a lot to do with how long they last. Saltwater and heat speed up degradation of the material and as it becomes less pliable regulator IP can become less responsive and more prone to change.
    If you tear a regulator down the only prudent thing to do is replace it..PERIOD. Only a complete idiot with no regard for safety would re-use one. Unfortunately I have seen it done many times.
    20170818_133317.jpg 20170818_133310.jpg
     
  9. Colliam7

    Colliam7 Tech Instructor Staff Member ScubaBoard Supporter

    # of Dives: 1,000 - 2,499
    Location: Kents Store, VA
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    The Zeagles are not particularly different. My speculation is that the diaphragm was older, had become a bit brittle, and finally flexed a few times too many, and cracked. Even a pin hole in an otherwise supple diaphragm is unlikely to lead to catastrophic failure. After it cracked, and gas rushed through, the 'explosion' was the environmental seal being blown out, after which gas was rushing out of the end of the first stage. Had no environmental seal been in place, the gas rush would have still occurred, but possibly the 'pop' of the environmental seal being displaced would not have been heard.

    Another possibility, I guess, is that the diaphragm clamping ring was simply not tightened sufficiently. If you don't have the proper tools (i.e. a pin spanner) and tighten it only by hand, it is possible that the diaphragm will pull out of position. If it was actually serviced by a tech who knew what they were doing, this seems unlikely. But, again, all of this is speculation.
    And, I use them just to keep salt water out of spaces where it can cause corrosion, even with immersion rinsing. :)
     
    Last edited: Aug 18, 2017
  10. uncfnp

    uncfnp Solo Diver ScubaBoard Supporter

    # of Dives: 500 - 999
    Location: North Carolina
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    So unlike a piston first stage where you can open it up and inspect it, if you open a diaphragm to inspect, the diaphragm will have to be replaced? Or do you mean it should simply be replaced at regular service intervals?
     
    Colliam7 likes this.

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