Fatality at Jersey Island

[HIGHwing]

You probably can't avoid that anyway.

 

[gianaameri]

So what you're saying is she had all the required training, and scuba parts necessary to complete this dive safely.

The BSAC report tells us she had all the required training (but not where she did her course and from which training agency material and which Hollis instructor, not that it matters of course).

The actual report was posted in the thread long ago unless it got accidentally deleted due to inadvertent knowledge burning when moving/deleting posts.

 

[flots am]

I could assemble a P2 with the CLs on backwards without any serious consequence. I cannot put two mushroom valves on the same side without suffering a likely fatal CO2 hit. Even a CO2 sensor would not have prevented this accident because unless the gas is flowing through the loop it will not read elevated CO2.
The O2 sensors likely have no effect on the outcome of this accident. The unit was flooded which likely killed the O2 sensors.
The smoking gun is the mushroom valve mixup and nothing else.

Why is any of this possible?

Assuming the RB wasn't built with hardware store parts, why does all this stuff fit together in more than one way?

How is it that a device designed operate underwater, where a failure can kill the user, has a failure mode that involves getting wet?

This all sounds like a terrible design, even if it's common practice.

If I were the manufacturer, I'd be freaking out about now.

 

[Dr. Lecter]

Sorry flots, but your ignorance of CCRs is showing...let me put it in OC terms. Let's say you'll be diving on backmount doubles with an iso manifold, and no other gas.

Take apart your second stages, pull out the diaphragms and all the retaining nuts/rings/washers/whatever. Now jam two diaphragms into one second stage, back to back, and screw the reg back together. Throw any remaining bits back into the other second stage and screw it back together. Assemble your rig and get on the boat. Turn on your posts.

When the second stage with two diaphrams in it starts free flowing because the lever is stuck in the open position, turn off its supply post and ignore the issue. Stick the other second stage in your face and splash off the boat without ensuring you can breathe off it. Drown when you take a breath of water from the second stage with no diaphragm in it.

How the Hell could anyone make underwater devices like that, where you could fit it all together wrong?!

 

[gianaameri]

Sorry flots, but your ignorance of CCRs is showing...let me put it in OC terms. Let's say you'll be diving on backmount doubles with an iso manifold, and no other gas.

Take apart your second stages, pull out the diaphragms and all the retaining nuts/rings/washers/whatever. Now jam two diaphragms into one second stage, back to back, and screw the reg back together. Throw any remaining bits back into the other second stage and screw it back together. Assemble your rig and get on the boat. Turn on your posts.

When the second stage with two diaphrams in it starts free flowing because the lever is stuck in the open position, turn off its supply post and ignore the issue. Stick the other second stage in your face and splash off the boat without ensuring you can breathe off it. Drown when you take a breath of water from the second stage with no diaphragm in it.

How the Hell could anyone make underwater devices like that, where you could fit it all together wrong?!

Taking apart a regulator, 1st, or 2nd stage, or both is a qualified and certified technician job, not to be carried out by the end-user.

Assembling a rebreather, like the deceased and her buddies did, is precisely a job to be done by the user.

PPE (Personal Protective Equipment) like a rebreather is to be designed to protect the user (i.e. the deceased from assembly error, for example) and not the factory technician.

So, there is a subtle difference you might have missssssed in your analogy.

DON'T TAKE APART 1ST AND/OR 2ND STAGES OR REBREATHER LIFE SUPPORT ELECTRONICS OR ITS COMPONENT PARTS. Only factory approved technicians can do that safely.

 

[flots am]

Sorry flots, but your ignorance of CCRs is showing...let me put it in OC terms. Let's say you'll be diving on backmount doubles with an iso manifold, and no other gas.

Take apart your second stages, pull out the diaphragms and all the retaining nuts/rings/washers/whatever. Now jam two diaphragms into one second stage, back to back, and screw the reg back together. Throw any remaining bits back into the other second stage and screw it back together. Assemble your rig and get on the boat. Turn on your posts.

When the second stage with two diaphrams in it starts free flowing because the lever is stuck in the open position, turn off its supply post and ignore the issue. Stick the other second stage in your face and splash off the boat without ensuring you can breathe off it. Drown when you take a breath of water from the second stage with no diaphragm in it.

How the Hell could anyone make underwater devices like that, where you could fit it all together wrong?!

It's not quite the same. OC works just fine with no sensors or electronics, and the regulator problem would be apparent immediately because one would breathe like crap and the other would give water.

While you can't fix stupid, underwater electronics that fails when it gets wet is just a setup for disaster as is critical plumbing that can be assembled wrong.

Given the high cost of failure and the subtle failure modes, RBs should be held to an even higher design standard than OC.

flots.

 

[Edward3c]

Taking apart a regulator, 1st, or 2nd stage, or both is a qualified and certified technician job, not to be carried out by the end-user.

Assembling a rebreather, like the deceased and her buddies did, is precisely a job to be done by the user.

PPE (Personal Protective Equipment) like a rebreather is to be designed to protect the user (i.e. the deceased from assembly error, for example) and not the factory technician.

So, there is a subtle difference you might have missssssed in your analogy.

DON'T TAKE APART 1ST AND/OR 2ND STAGES OR REBREATHER LIFE SUPPORT ELECTRONICS OR ITS COMPONENT PARTS. Only factory approved technicians can do that safely.

You don't know UK divers then. If it can be stripped down to see how it works it will be. Why pay good dosh when we can service things ourselves.

 

[gianaameri]

You don't know UK divers then. If it can be stripped down to see how it works it will be. Why pay good dosh when we can service things ourselves.

I service my regulators, but I did an A.S.S.E.T. course and buy Service Kits in the black market (very Tec because it is "black").

Nonetheless, I should not because I am not a Factory Approved Technician and certainly if I lent my regulator to somebody else I would be looking at a few years in jail in case of an accident.

I don't do it to save money (bad economy), but to learn about the equipment I use (I actually hate servicing regulators).

The key thing in the case of the deceased is that she did NOT perform something on her equipment which was reserved to a FAT ("Factory Approved Technician").

She did no more and no less what would amount in OC to put together regulator, tank, and BCD, and go diving, but she stopped moving 3 minutes into the dive.

 

[descent]

... The coroner noted that the air cells read drastically lower FO2 than actual. ... The cell readings should have also shown the breathing loop issues she had. ...

Victor, that's really interesting. I have been overlooking/ignoring the sensors because they were found in a flooded unit.

The official cause of death has been bothering me, though. The recovered computer said the diver was motionless within a few minutes. In shallow water, without huge exertion, hypercapnia just doesn't sound likely to me.

Your comment made me wonder if the cause of death might not have been hypercapnia, after all.

Even with old cells, it is reasonable to expect that her console could have showed 0.21 during pre-dive tests.

Sometimes old galvanic oxygen sensors degrade in a non-linear way. They read OK at the surface, but cannot generate enough electricity as the partial pressure of oxygen rises. The low current tricks the diver (or the rig's electronics) into increasing oxygen levels in the loop beyond what is safe.

Manufacturers of cells, rebreather designers, and prudent end users all agree: using O2 sensors after the date indicated by the manufacturer is not wise. If you value your life at all, saving money by using old cells is a false economy, and an easily avoidable risk.

The first thirty seconds of the dive probably would have been uneventful. But if the failing O2 sensors started underreporting as the partial pressure of oxygen rose, and if she had a typically high setpoint (above 0.4), the solenoid would have fired and stayed wide open.

The solenoid would not have turned off until the sensors reported a correct setpoint. With current-limited cells, the setpoint is unattainable. The oxygen inflow does not stop until the diver closes the tank valve.

The recommended maximum depth for an oxygen-only rebreather is twenty feet. IIRC, her body was found deeper than that.

With a confused, distressed, and hypercapnic diver with a misconfigured rig, I can see how this scenario leads to hyperoxia, a seizure, and a blocked airway in under three minutes.

 

[Dr. Lecter]

Taking apart a regulator, 1st, or 2nd stage, or both is a qualified and certified technician job, not to be carried out by the end-user.

You're ing kidding me, right? Taking apart and cleaning out the 2nd stage by removing the purge cover and diaphram is not only something everyone should know how to do for purposes of cleaning, it's something many of us drill doing underwater while diving​. Stuff gets stuck in there, and knowing how to remove it and clear the lever/diaphragm to function again is an important skill for anyone carrying stage/deco/bailout bottles.