Report from Fatality at Devil’s Ear

jaap

Hi

This OPV talk is perhaps expanding off topic, so perhaps its time for a dedicated thread?

Anyway, I have also thought about using a BCD OPV instead (of course removing any eventual toggles or things that can be used to pull it). It should also protect against the possibility of an ordinary dry suit type OPV to slowly flood if inadvertedly pushed in by some object. I had a dry suit type OPV partially flood one of my sling Rebreather because of this. Also had things pushing on the OPV of my CK making the unit temporarily go open loop due to gas dumping (no flooding though, despite the top OPV position)

If going for a BCD OPV I would prefer to get one with double membranes, I think AP valves (Buddy) uses dual serial membranes in some of their dumps?
And to make some sort of assement of if or how much larger the risk of embolisms becomes on rapid CC-ascents with nose/mouth venting. Or the risk of bursting the loop in OC ascents. On loops with more variable volume I would definately be worried of run away ascents (not on the CK).


The Viking X2 dry suit dump valve could also be worth mentioning:

http://www.trelleborg.com/protective...03-04%20EU.pdf

Only trouble with the X2 (apart from the higher price) is they use a different hole/thread compared to the more common Sitech/Apeks type ones. So retrofitting one could be tricky on a Rebreather unless there is space for some adapter (I know there are adapters/rebuildkits to mount them on suits made for other valves).

__________________
My initials: JAAP

Marc T

L

One of my previous BOB system had BMCL ADV and OPV from BCD he was most of the time "living its own life" during the dive...never seen water in the CL

One of my actual BOB is riged inside a PVC pipe with the lung collapsed by the breathing hoses and mouthpiece pushed inside the pipe and have an OPV with strong spring, it has been many times staged betwween 12 and 45 meters depending on the dive ( and with no more feed gas when let alone )... neither seen water inside either.

My main Rebreather will always stand by me either and I prefer when its the same for my BOB.

Note about OPV that there is not much water in a SCR system with the OPV firing all the time, so probably the water come in during the shut off phase

db8us

We have deposited our breathers for several hours while sitting in the habitat without problems. Also the use as a sidemount was no problem when it comes to water intrusion.
So there must be a flaw there or maybe dirt in the OPV?

Regards

Michael

farmerted

Hey all,
interesting discussion here. the dsv was closed, FULLY. all of the teams involved checked this. There are several places along this dive plan that involve scraping through. This would lead to the opv in question dragging through the silt or sand(mostly sand). 3 days after the recovery, I still had questions and decided to go a little further than where we conducted the recovery. The passage was tight, but back mountable. I then entered a room(where the unit was reported to be removed and stowed) with a low ceiling . depending on where it was removed would dictate yet another scrape. The floor was complete silt and at this point i realized what a complete mess Mark had probably returned to.

Drmike

yes I did the same thing. or you can just use a stronger spring.

I used an OPV from a liftbag with sucess.

__________________
Get a girlfriend you sad twat - a Rebreather is an unfaithful mistress - dont blind yourself to her faults just because she goes down on you

jaap

OK

But does that say anything about wether the DSV was really fully closed while it was left unatended? Didn't the diver return to the unit and attempt to use it just before things got really bad? So the DSV could have been shut properly the last time but not while being staged behind?

__________________
My initials: JAAP

Jerry

Either he never went back on the loop or he closed the DSV prior to his attempt to get to his staged bailout.

If he didn't get back on the loop then it didn't leak through the DSV. If he did try the loop and then managed to RECLOSE the DSV in the midst of probable near panic, it would stand to reason that he very probably had it closed while away from it.

Jerry

Jerry

Here's a scenario for the Monday Morning quarterbacks; a rig passes the predive checks (pos/neg tests); it is found on the deceased nearly 24 hrs later, scubber down; onboard oxygen to solenoid empty; CLs full of gas and floating upward placing the OPV at the highest point; the OPV is witnessed venting; the DSV is closed; where did the water filling the scrubber come from???


Jerry

Nailer99

Thanks for posting. Between your post, and the previous discussion of OPV failure possibilities (thanks, Dr. Mike), I now believe that the OPV may have been the ingress point for the flooding- I think I'll clean mine really well this weekend.

db8us

What CAN go wrong WILL go wrong!

Inital there was ne mesh over the exhaust holes in the RB80. While diving in Ginnie (strange coinsident) a small piece of rock got into the rebreather (also past the Hinkel) and it made it impossible for the counterlung to fully expand.
So the unit was wasting gas in huge quantities.
I heard the unit dumping gas and asked Reinhard to check it. We discussed short in the wetnotes while beeing OC (the first thing to do) that it might still safe some gas if staying on the loop.

We had (as always) ample bailoutgas for even both of us to get out OC.
After dissasembling the unit we found the peice of rock and decided to cover these holes with mesh.

No matter what the route cause was, with bailout gas at the unit he should have been able to survive.
Also a realitycheck by a second diver (not in distress) might have contributed to survival.

Of course this is extreme diving and the second diver might have been useless in this visibility but then even more bailoutgas should have been right there.

And: If in doubt: Bail out...

My 2 Rupees from India

Michael