Rebreather NSS/CDS report from death at Peacock earlier this year.

[Invader]

Didn't see a thread for this.

https://nsscds.org/wp-content/uploads/2025/06/Peacock-Springs-2025.02.01.pdf

 

[jengineer61]

In aviation there is a type of accident there one failure does not lead to an accident there could be 3 ,4 or more failures might occur without the plane coming down. the model is called a swiss cheese model of accidents. The issue comes up when all those holes come into alignment and then you have a failure. I am not versed with CCR but empty dilutent and not making up the balanced canister length are two holes. The third, and this one breaks one heart, is the dive buddy asking if everything was ok before the dive got into the overhead.

 

[rjack321]

In aviation there is a type of accident there one failure does not lead to an accident there could be 3 ,4 or more failures might occur without the plane coming down. the model is called a swiss cheese model of accidents. The issue comes up when all those holes come into alignment and then you have a failure. I am not versed with CCR but empty dilutent and not making up the balanced canister length are two holes. The third, and this one breaks one heart, is the dive buddy asking if everything was ok before the dive got into the overhead.

The diluent was likely emptied by the diver trying to flush the loop or the loop volume crashing due to extremely high respirations firing the ADV. It's a consequence of the CO2 breakthrough, not a cause.

The fact that the make & model of CCR isn't identified is problematic. It's entirely possible to "design out" the kind of failure this diver experienced. Manufacturer's who fail to do so should be name and shamed instead of putting all the blame here on the diver's assembly mistake.

 

[Kay Dee]

The report talks of scrubber 'cartridges'. Is that implying 1) prepacked cartridges, i.e. bought packed or 2) just smaller 'cartridges' that the user / diver packs that then fit inside a larger scrubber cannister?

 

[Manatee Diver]

The report talks of scrubber 'cartridges'. Is that implying 1) prepacked cartridges, i.e. bought packed or 2) just smaller 'cartridges' that the user / diver packs that then fit inside a larger scrubber cannister?

There are a couple of units where you can fit a smaller scrubber canister that you pack using a spacer.

@rjack321 Another question I would like to ask, did the diver use a build check list? And is checking on the spacer part of the checklist?

 

[fullytek]

The diluent was likely emptied by the diver trying to flush the loop or the loop volume crashing due to extremely high respirations firing the ADV. It's a consequence of the CO2 breakthrough, not a cause.

The fact that the make & model of CCR isn't identified is problematic. It's entirely possible to "design out" the kind of failure this diver experienced. Manufacturer's who fail to do so should be name and shamed instead of putting all the blame here on the diver's assembly mistake.

The make of the rebreather in the case was a meg. Megs are likely the most robust and reliable machine in the industry.

I spent alot of time trying to think of a way to design this potential failure out of the unit. And can't really come up with a reliable solution.

Also note that the defender and xxcr have the same potential failure mode


Ultimately this may have been prevented by following the build checklist and the pre jump procedure.

 

[Rollin Bonz]

Semi revelant discussion

Thread 'Half-packing sorb -- Possible, or deadly?'

Mar 10, 2025

The recent thread about the Dive Talk GO got me thinking... One of that unit's features is a small scrubber. Its limited sorb capacity makes this particular rebreather only suitable for non-expedition-type dives, but for that particular use case, the small scrubber seems reasonable.

Let's assume, then, that a diver has a rebreather with a standard-capacity scrubber (say four or five hours' worth of sorb). This diver has a use case in which they'll be doing a 1.5-hour one-off dive, or maybe two relatively quick dives. The diver doesn't want to go OC, and storing the partially used sorb...

• stretchthepenn
• Replies: 70
• Forum: Rebreather Diving

• 

 

[DOBY]

The fact that the make & model of CCR isn't identified is problematic. It's entirely possible to "design out" the kind of failure this diver experienced. Manufacturer's who fail to do so should be name and shamed instead of putting all the blame here on the diver's assembly mistake.

The Meg, SugGravity Defender, and XCCR all allow for different size (vertical length) scrubbers and corresponding spacers. I went to just using the standard 8# scrubber and appropriate spacer to avoid this potential operator error issue.

Please elaborate on how it’s possible to “design out” this kind of failure (operator error).

 

[Dsix36]

Personally I think that any scrubber that utilizes a spacer is dangerous since omitting the spacer or using one that is too short will lead to this exact scenario. The simple fact that people want to be able to use different size cans and scrubbers without needing to buy all the necessary components again is the only reason that this is even possible. Having the appropriate spacer built into the bottom of the scrubber is the only solution I can see unless the use of multiple size scrubbers is eliminated. When I had my defender, the first thing I did was use a paint pen to mark the inside of my can so that during assembly it was blindly apparent if I had left the spacer out, even using a check list my "mark" caught my mistake once. Once is all it would have taken to having a report like this one written about me.

 

[DOBY]

Personally I think that any scrubber that utilizes a spacer is dangerous since omitting the spacer or using one that is too short will lead to this exact scenario. The simple fact that people want to be able to use different size cans and scrubbers without needing to buy all the necessary components again is the only reason that this is even possible. Having the appropriate spacer built into the bottom of the scrubber is the only solution I can see unless the use of multiple size scrubbers is eliminated. When I had my defender, the first thing I did was use a paint pen to mark the inside of my can so that during assembly it was blindly apparent if I had left the spacer out, even using a check list my "mark" caught my mistake once. Once is all it would have taken to having a report like this one written about me.

Hammerhead gave out stickers to put in the canister to indicate proper scrubber height.