Fatality at Jersey Island

[victorzamora]

I agree. I have to tell you though, the assembly procedure you're requesting required me to actually visualize if it is even possible. I refuse to debate the standards and checklists issues with you. I just don't see how the knurled ring on the DSV has enough tolerance to allow both mushroom valves to be seated. My guess is result is the loop will not pass a negative because the loop will not be air tight. More on that later.

For those of you who somewhat familiar with rebreathers and following along, I want to make an overarching statement about the proposed assembly. This assembly procedure I'm going to replicate to my knowledge has never happened before in the wild. For this maganitude of an assembly error requires more than a single missed test on a list, or an oversight, essentially the majority of the loop has to be built incorrectly. As you may have noticed, I couldn't even intially understand how it was done desipte the lengthy discussion. It is my position prior to trying it in the first person there is no way this rebreather could possibly have passed the tests included in the Assembly Checklist.

That's really interesting to read. I'd love to hear your findings, what failures were required and what all had to be missed.

 

[HIGHwing]

once she put the lungs on the wrong side , it looks to me she just went dot to dot , as that the only way it would all fit ,
dsv was the right way , just bad news for her that the inhale flipper valve sits in the hose...

Interesting theory. That could imply the DSV was installed quite literally upside down. These actions would indeed orient the press fit mushroom valve against the inhalation mushroom valve bisecting the loop. That would be *very* relevant as to how to do this, again, if it is even possible. BTW - Hollis marks the DSV with a label that says "Pre-Breathe" atop it from the factory which would give a cue to it's proper orientation. But, G-man seems to think her loop was from a lot of a different variant than the current production model. Either way, I can only test what I have available.

To accomplish this feat, you'd have to install the hoses to the head, put the counterlungs on the wrong sides, the lower loop hoses might be facing slightly inward instead of outward (if she hadn't competely disassembled the loop), the oxygen and diluient hoses would not fit correctly (but can be pulled or re-routed to make it work), *AND* the DSV would have to be inverted. So basically you'd have to perform nearly every step of the assembly incorrectly minus attaching the tanks and latching the scrubber bucket.

The interesting thing about assembly in this way, is that the unit should pass both the Positive and Negative tests. It also implies one other *very* relevant finding. If she built the loop this way, or was taught to do so, it eliminates the possiblity of a stereo test. This means conclusively she did not follow the checklist or build procedure. The Assembly Checklist will catch the error being blamed for her death unless you build it top-down as you suggest, because you can't perform that test.

This is where experience comes into play. An experienced rebreather diver would still likely catch this error. You would notice both lungs would be inflating and deflating in sync, which is an immediate ABORT, strip, and diagnose.

 

[gobfish1]

Interesting theory. That would imply the DSV was installed quite literally upside down. This would indeed orient the press fit mushroom valve against the inhalation mushroom valve bisecting the loop. That would be *very* relevant as to how to do this, again, if it is even possible. BTW - Hollis marks the DSV with a label that says "Pre-Breathe" atop it from the factory which would give a cue to it's proper orientation. But, G-man seems to think her loop was from a lot of a different variant than the current production model. Either way, I can only test what I have available.

To accomplish this feat, you'd have to incorrectly install the hoses to the head, put the counterlungs on the wrong sides, the lower loop hoses would be facing the wrong way, the oxygen and diluient hoses would not fit correctly (but can be pulled or re-routed to make it work), *AND* the DSV would have to be inverted. So basically you'd have to perform nearly every step of the assembly incorrectly minus attaching the tanks and latching the scrubber bucket.

The interesting thing about assembly in this way, is that the unit should pass both the Positive and Negative tests. It also implies one other *very* relevant finding. If she built the loop this way, or was taught to do so, it eliminates the possiblity of a stereo test. This means conclusively she did not follow the checklist or build procedure. The Assembly Checklist will catch the error being blamed for her death unless you build it top-down as you suggest, because you can't perform that test.

i think the DSV was the right way up , and only the lung to hose part,s are keyed , not seen the unit so im just talking bollox , but having the DSV up side down im sure some from the team of 3 dives would have spotted that ,

i dont know , whats keyed and whats not ,

 

[HIGHwing]

Fair enough, but if the DSV is installed upside down, hmm.

My first theory: Installing the DSV upside down would likely allow her to complete the build without any problems, except the counterlungs might end up on the wrong side. She would have unknowingly blocked the gas movement in the loop. She can now easily pass positive and negative tests confidently, but she'd have to really pay attention to the stereo test. She can very easily declare the stereo test passed, because she would be able to mistake breathing out of only one side of the loop.

I'll be testing this possibility. This seems possible to me, so I'll have to try it. From my understanding she travelled the unit, which means she broke it down to pack it. This creates the liklihood she wouldn't have any twisted hoses becuase she would just orient them as necessary while building the loop. All this really makes me think she built the loop to go dive and it makes me wonder if she started with the DSV upside down.

My second theory: She left the lower loop hoses connected to the counterlungs for shipping/travel and simply connected the inhale hose to the exhale side of a properly oriented (Face Up) DSV. By doing this, she would have blocked the gas movement in the loop and created a plastic bag to breathe in (same as above) now the mushroom valves would have been right next to each other blocking the circular gas flow by bisecting the loop, but not in any way impeding breathability. I believe this is most likley what happened. Though I will point out that I don't know if the DSV can be screwed down tight in this configuration - but it would allow her to pass every assembly test but the stereo (same as above). This would have been a much easier mistake to make. Again the diver should notice the lungs are breathing in sync and catch the assembly problem.

It should be noted that this is where Open-Circuit thinking hurts CCR divers. I can breathe normally, so I'm good and the test passes. A proper stereo test will unquestionably save her life from this error, and she has the opportunity to catch the error during the Assembly Post Check, Pre-Dive, and Pre-breathe, but her limited experience possibly clouded by her excitement lets her down on this dive, IMO. It's imperative for her to notice the lungs are inflating and deflating in sync during the pre-breathe as a last resort. IF she doesn't notice this very subtle problem, it's game over.

 

[boulderjohn]

I would just like to step in as a interested observer and say that this is turning out to be one of the more valuable A & I threads ever, at least for me.

 

[gianaameri]

But, G-man seems to think her loop was from a lot of a different variant than the current production model.

"The inquest was informed that the manufacturer, Hollis, has now modified the mouthpiece assembly and re-issued it."

Not my opinion or belief. It comes from the Coroner.

Your unit being the very latest HP2 variant should not display any of the problems encountered by the deceased because these have been since corrected by the manufacturer.

---------- Post added December 2nd, 2014 at 03:46 PM ----------

Yikes. I hope the remaining seven divers have been carefully studying what happened in Jersey.

My sincere hope is that Hollis was able to identify those units by serial number and individually contacted the owners long ago to warn them of the risks and issue to them a new rebreather loop free of charge.

 

[descent]

Given that several people who own a Prism 2 have already described the idea of building the lower loop upside down as an unimaginable failure mode, I am guessing that "verify that the embossed directional mark is on the top of the DSV" [-]will[/-] [does] not appear [-]on the checklist[/-] [in the published manual] before any prebreathing step [because: previous astonishment is probably even greater inside Hollis Inc].

If Omisson is reading, perhaps he could ask the Coroner if the equipment was photographed immediately after recovery.

If images of the (mis)connected loop exist, they may show an upside down DSV. As Tammy pointed out, the top surface of the valve should be embossed with a directional marking, visible when the lower loop is correctly assembled.

 

[gianaameri]

"DSV (DIVE SURFACE VALVE)The Dive Surface Valve (Fig. 1.15) is a neutrally buoyant one-way loop
“shut down” valve with a water purge. The rotating barrel is made of
stainless steel. The exhalation mushroom valve is seated on the right side
of the valve housing." (from the HP2 current manual).

 

[Douglas Ward]

"The inquest was informed that the manufacturer, Hollis, has now modified the mouthpiece assembly and re-issued it."

Not my opinion or belief. It comes from the Coroner.

Your unit being the very latest HP2 variant should not display any of the problems encountered by the deceased because these have been since corrected by the manufacturer.

---------- Post added December 2nd, 2014 at 03:46 PM ----------



My sincere hope is that Hollis was able to identify those units by serial number and individually contacted the owners long ago to warn them of the risks and issue to them a new rebreather loop free of charge.

The Hollis BOV was has the mushroom valves seated on either side of the BOV and is nearly impossible to install upside down.
The Hollis DSV has a mushroom valve seated in the inhalation side (diver left) hose (not the DSV body) the exhalation mushroom valve is seated in the DSV body on Diver right.

The Prism is available for purchase in both configurations. DSV or BOV.

The recall on the BOV was due to non conforming materials during manufacturing. There is no recall for the DSV.

Just a clarification. Dont confuse the BOV and the DSV. Two very different things and both available for purchase.

 

[HIGHwing]

G-man,

Let's agree the loop is a piece of black hose and the counter lungs are nothing more than fancy balloons at the mid-point of the hose connected to a plastic bucket on the end. Ideally the gas flows around in a circle from mouth piece to balloon, to bucket, to balloon, past a one-way valve to assure gas direction, to the mouthpiece (individual designs will vary). If the accident victim puts a stopper in the black hose beyond one of the balloons she has successfully created simultaneous access to both balloons with a single hose. It appears that's precisely what we're trying to solve. How could she make a mistake that completely changed the airflow from circular, i.e. down the hose, through the exhale balloon, through the scrubber, through the inhale balloon, past the one-way valve, and finally to the mouthpiece versus breathing into both balloons and bucket simultaneously. (And that's how simple a rebreather really is... Scary, right?) Of course, she can breathe into and out of the balloon at will until the CO2 inside the airbag to bucket combo she inadvertently created overcomes her - moments into the dive.

You're certainly welcome to make this about design problems, standards that no manufacturer can achieve, or whatever tickels your fancy. The fact is few if any people are learning anything from what you're posting other than the same "recycled" and slightly edited stuff you've applied to every CCR accident covered on the Internet since the dawn of time. The people follwing this thread want to know how it's possible to make this error, and how to *prevent* this error. Are there cues to look for in a bad assembly, and can a buddy check or perhaps a checklist modification prevent this accident in the future? I know this from private messages, and emails I've received today.

My goal is to make this assembly error understandable to someone who knows essentially nothing about rebreathers other than, "I think they're dangerous and complicated". The fact is, these are people who don't understand a rebreather is really two hoses, two balloons, a one-way valve, and a bucket. Ask any qualified rebreather diver if they think their machine is "complex", you'd be surprised the answer you might receive.

I salute your efforts, but I believe your energy is simply misplaced. When you light fires and burn bridges eventually you find yourself mayor of your own island with no escape route. You've made your point, we get it, and we rebreather divers - yourself included - accept the known risks and dive what the manufacturers provide often with modifications that suit our needs and the environments we dive. I think you should reevaluate your playbook if you want to make a positive difference in the CCR community.