Fiona Sharp death in Bonaire

[fsardone]

GENERALLY speaking, the dil will be added on the inhale side and O2 on the exhale. This is to allow the O2 to mix on its way through the machine, avoiding localised spikes (If you, for example, breathed very rapidly and O2 was being added just before the mouth, you could be breathing next to pure O2 as the machine tried to raise the set point)

This design is to avoid the issue you mention, as well as to allow you to immediately get the "good gas" if you need to do a dil flush in case of a hot loop composition. Thats not to say all units are like that, but it is a pretty constant design paradigm in the industry.

Exactly, and that is the reason why I dump from the nose. It clears my mask if needed, it is dumping used gas it does not require to use hands and it is done instinctively.
Concerning dump valve, mileage varies. My unit, for example, has two: one for each counterlung so I can choose (provided I have both hands free) which one to use, but both the Oxy MAV inlet and the solenoid are downstream from the closest dump valve. Those are used when I ascend OC for training ...

 

[skippy311]

On the right hand of God was his soul

Thanks for the translation and sorry for the hassle.

 

[Dan]

Thanks for the translation and sorry for the hassle.

No hassle. I was curious about it myself.

 

[InTheDrink]

Not adding anything to the loop would help reduce the po2. Adding either gas would increase it, one to a lesser degree. If she flushed with diluent at her target depth her po2 would spike to 2.0 . Not a good idea.

I’m not trying to be facetious but a PPO2 of 2.0 over a reasonable period is fine in a healthy person. I wouldn’t recommend it tho.

I’d be extremely surprised if this was the COD.

Bad cells could be a contributing factor but given her experience I’d be surprised that she would knowingly dive at more than 1.3.

Bad scrubber sounds more plausible and a CO2 hit. Also IPE/NPEE.

I’d guess - just guess - it was breakthrough or/and a medical event. Hypoxia doesn’t square up given her experience. Hyperoxia equally does not add up unless cells were ******.

CCRs are machines. They break. People always blame it on pilot error.

That’s a facile and unacceptable analysis.

RIP.

 

[Peter69_56]

GENERALLY speaking, the dil will be added on the inhale side and O2 on the exhale. This is to allow the O2 to mix on its way through the machine, avoiding localised spikes (If you, for example, breathed very rapidly and O2 was being added just before the mouth, you could be breathing next to pure O2 as the machine tried to raise the set point)

This design is to avoid the issue you mention, as well as to allow you to immediately get the "good gas" if you need to do a dil flush in case of a hot loop composition. Thats not to say all units are like that, but it is a pretty constant design paradigm in the industry.

My breather adds gas as you said, under the inhale side canister, via a solenoid and via the DIL valve. However if I manually add gas, DIL or Oxygen, it goes into the loop via a port on the loop relief valve. I would have expected it to have a tube directing it to the same place where the O2 solenoid is, but it doesn't. It simply stops at the inlet port on the loop relief valve, thus if I have a high loop volume when ascending and I don't dump some gas before adding oxygen, the oxygen simply exhausts out via the loop relief valve when the dump pressure is made. I think a poor design, however as I am aware of it I always ensure I vent the loop before adding oxygen on ascent. Something normally done anyway, but in my mind a poor design and something easily fixed. Adding a tube running down to the centre of the loop under the canister would ensure, that even if I didn't dump gas prior to injecting oxygen, I would at least not lose the injected oxygen. Something I am working on (trying to get the right fittings).

 

[lermontov]

My breather adds gas as you said, under the inhale side canister, via a solenoid and via the DIL valve. However if I manually add gas, DIL or Oxygen, it goes into the loop via a port on the loop relief valve. I would have expected it to have a tube directing it to the same place where the O2 solenoid is, but it doesn't. It simply stops at the inlet port on the loop relief valve, thus if I have a high loop volume when ascending and I don't dump some gas before adding oxygen, the oxygen simply exhausts out via the loop relief valve when the dump pressure is made. I think a poor design, however as I am aware of it I always ensure I vent the loop before adding oxygen on ascent. Something normally done anyway, but in my mind a poor design and something easily fixed. Adding a tube running down to the centre of the loop under the canister would ensure, that even if I didn't dump gas prior to injecting oxygen, I would at least not lose the injected oxygen. Something I am working on (trying to get the right fittings).

wouldn't exhaling through the nose short circuit that so the OPV isnt activated

 

[lermontov]

CCRs are machines. They break. People always blame it on pilot error.

That’s a facile and unacceptable analysis.

RIP.

so given the analysis of ccr related deaths what % are machine breakdown versus human error

 

[InTheDrink]

so given the analysis of ccr related deaths what % are machine breakdown versus human error

There was a reason Cousteau created OC.

Full facts?

You’ll find exactly none.

Cell disagreement you could find plenty.

IPE/NPE because of loop vol or ADV likewise.

Overbreathing an eCCR never mind break though.

Three Hs.

Yep all pilot error except OC has anecdotally (as we don’t have proper facts) is about 90% lower.

But let’s just call all it pilot error.

I’m sure that will fix things for extremely experienced pilots.

 

[Peter69_56]

wouldn't exhaling through the nose short circuit that so the OPV isnt activated

Yes thats what I do, but my point being to highlight a flaw where one can lose a lot of oxygen trying to manually raise PPO2 in ascent if it isnt done properly. Something like this in a panic or less than ideal situation could cause a low PPO2 and blackout. Not with all breathers but in some. For it to happen to me, my solenoid would have had to fail or flat controller battery thus firing on manual, and not venting gas before injecting oxygen manually, and not monitoring at my PPO2 could lead to blackout.

So it is a possibility to ascend and have a hypoxic mix under some circumstances.

 

[rjack321]

so given the analysis of ccr related deaths what % are machine breakdown versus human error

It's not that simple. There is almost always multiple things going on simultaneously in a CCR fatality. Distracted diver, small broken thing, weak feedback loop that there's a small problem then turns into a big problem, buddy looks away, and all the issues seem to magically align and the diver dies. Was it the broken thing? The moment of distraction? the inattentive buddy? poor training? a design weakness in that particular unit? Often its a little bit of each.