CCR Selection priorities

[Brad_Horn]

One thing that hasn't been addressed that is on my list, is the identity and ease of forgetting the Widow Maker. All the units I've dove, tried in the pool, or at least have seen a detailed enough build have something somewhere that you can forget or misplace that will not affect a positive or negative test, but will still kill you. They are usually o-rings separating the inhale side from the exhale side. On the inspo it is the scrubber can o-ring. On the SF2 it is the o-ring on the nut that keeps the bottom of the head plate attached. On a MK15 it is the duct tape/ inner tube that keeps the scrubber together (!). Old megs had the string hack that could get trapped and cause bypass. I don't remember what it was on the drager units.

An important consideration for the rebreathers FMECA that should be addressed https://www.opensafetyglobal.com/Safety_files/FMECA_OR_V4_180821.pdf

There's still a good bottle of single malt on offer I believe if anyone can identify a critical safety design issue - like you've identified above - on the Apocalypse Type IV CCR. The closest I believe someone has come is reporting that the flood recover drain OPVs needed to be better and reliable seal 100% of the time; as they now do. You certainly can't miss-assemble one and have it pass +/- in a wearable diveable condition. The seals/o-rings are all retained so if you strip it to insert a new scrubber and reseal it noting will be left behind. No tools are required for this.

 

[grantctobin]

An important consideration for the rebreathers FMECA that should be addressed https://www.opensafetyglobal.com/Safety_files/FMECA_OR_V4_180821.pdf

There's still a good bottle of single malt on offer I believe if anyone can identify a critical safety design issue - like you've identified above - on the Apocalypse Type IV CCR. The closest I believe someone has come is reporting that the flood recover drain OPVs needed to be better and reliable seal 100% of the time; as they now do. You certainly can't miss-assemble one and have it pass +/- in a wearable diveable condition. The seals/o-rings are all retained so if you strip it to insert a new scrubber and reseal it noting will be left behind. No tools are required for this.

Classic. Won’t respond to @kierentec questions regarding the Dive Rite issue, still comes in to peddle a product none of us will ever see nor use.

 

[_Ralph]

Slightly OT, but since people are bringing up ‘forgetting an oring’.. and needing several pages and dozens of steps..

How far are you guys disassembling your units on a day to day basis??

I break my sidekick down to 7 parts:
1/ waste bin (aka, body)
2/ head
3/ Loop hoses
4/ DSV
5/ Scrubber
6/ Scrubber lid/spring/wire mesh
7/ Tanks

I do visually check orings on each build, and once a year, do a full check/replace/rebuild


_R

 

[Brad_Horn]

Cool PDF. I guess you weren’t able to track down the actual video of the testing conducted to “prove” the point as expert witness testimony. No worries, I’ve got it right here for those in the audience who are unaware of the type of testing conducted by “deep life” and “open safety”.

Cheers Mate. You're right I haven't seen either before. Certainly serves as proof of concept. But at the same time it is worth considering the somewhat scarier fact that is I understand also the best and only testing done to date on that rebreathers PPO2 controlling electronics.....

Should it be something that is filmed professionally to demonstrate the risk, most definitely. Would it have mattered to the outcome of that case, unlikely.

Anyone at home with an eCCR that uses voting logic can replicate this design issue just by covering 2 of their cells faces with water while in oxygen and then exposing to air to see what the rebreather elecs thinks you are breathing. Which will give you Hypoxia. Flip the gases and you get Hyperoxia. Only takes a few drops of water to cover the cell faces. Again have a read https://www.opensafetyglobal.com/Safety_files/DV_O2_cell_study_E4_160415.pdf

 

[Garth]

I would assume CE rating would make units safer however doesn't the diver make the unit safe? I was always under the impression that the diver was the one element of any CCR that could make or break the success of a dive from the build, to the dive, to the maintenance, to the plan.

I dive a hammerheadCCR that i don't believe i could over breathe if i tried. It seems perfect for anything that isn't a tight squeeze but my only thing would be it doesn't dive well with a wetsuit for me, so I don't dive wet. I also get some back pain after long dives on the DPV with lots of bailout but i doubt that is the rebreather it could be trim and position and a personal thing with me.

I also now dive a KISS sidewinder which i'm new on. It dives great in almost all orientations, still get some chipmunk cheaks when completely head up but other than that it breathes well. I think its a lot less tolerant to over breathing compared to the HHCCR but in all reality it dives incredible. The loop volume is way less and adjustments can be made quicker. I really like mCCR.

 

[kensuf]

I would assume CE rating would make units safer however doesn't the diver make the unit safe? I was always under the impression that the diver was the one element of any CCR that could make or break the success of a dive from the build, to the dive, to the maintenance, to the plan.

I dive a hammerheadCCR that i don't believe i could over breathe if i tried. It seems perfect for anything that isn't a tight squeeze but my only thing would be it doesn't dive well with a wetsuit for me, so I don't dive wet. I also get some back pain after long dives on the DPV with lots of bailout but i doubt that is the rebreather it could be trim and position and a personal thing with me.

I also now dive a KISS sidewinder which i'm new on. It dives great in almost all orientations, still get some chipmunk cheaks when completely head up but other than that it breathes well. I think its a lot less tolerant to over breathing compared to the HHCCR but in all reality it dives incredible. The loop volume is way less and adjustments can be made quicker. I really like mCCR.

There's a lot to <3 about mCCR. The philosophy of keeping you engaged in the rebreather pays dividends.

Don't think a lack of a CE rating implies a unit is unsafe. Some manufacturers may have simply decided a CE rating is not worth the price given their market / marketshare. And at the same time, don't believe a CE rating means a unit is safe -- there are supposedly ways to game the testing to earn a CE rating, the group requesting the testing can specify certain parameters such as orientation of the rebreather, which can play a huge role in hydrostatic work of breathing.

 

[cathal]

there are supposedly ways to game the testing to earn a CE rating, the group requesting the testing can specify certain parameters such as orientation of the rebreather, which can play a huge role in hydrostatic work of breathing.

Thats a profoundly serious and shocking accusation against the CE testing standard if true. Just wondering can you provide any proof of this.

 

[Brad_Horn]

There are supposedly ways to game the testing to earn a CE rating, the group requesting the testing can specify certain parameters such as orientation of the rebreather, which can play a huge role in hydrostatic work of breathing.

You don’t even need to game it, you can openly declare a failure to meet the standard, as an exception on the units CE certification:
https://www.vmsrebreathers.com/downloads/VMS_RED_Series_Manual_v_2.0.3.pdf
“EN14143:2013
Excluding Section 5.6.1.4 (See section on Hydrostatic Imbalance)

The VMS RED SERIES do not meet section 5.6.4.1 of the EN14143:2013 standard. The unit does not pass on the +180 (lying on back position), or -90 (head down position) if the ADV is active, as the pressure is artificially increased due to the ADV firing (as it is below you in these orientations). Should you need to operate in these orientations you simply need to isolate the ADV using the slider on the gas block), and maintain your loop volume manually.The units do however comply in all other orientations.”

Or as you indicate one seemingly can opt to ignore any design inconveniences found during testing, though it really ought to still be noted in the units technical file but one could maybe guess there are instances where some are overly forgetful:
http://www.josephcaruana.co.uk/divi...test-data-for-two-closed-circuit-rebreathers/
https://www.hollisrebreathers.com/wp-content/uploads/2019/08/QQ-1900385-HollisPrism-v1-1.pdf

Or test and document everything ensuring every requirement is met:
https://www.opensafetyglobal.com/Safety_files/DV_DLOR_HydroImbal_101116.pdf

 

[broncobowsher]

That sounds like the early Teslas, the repowered Lotus cars. They had a list of "does not meet FMVSS xxxx" notifications. But were sold anyway.

 

[kensuf]

Thats a profoundly serious and shocking accusation against the CE testing standard if true. Just wondering can you provide any proof of this.

"Supposedly" -- I openly admit what I heard is not substantiated by concrete evidence in my hand. The person that told me this used to be a distributor for a CCR that is CE rated.

And as Brad said, you can alert failures. My JJ has a notification on page 11 of the owners manual (https://jj-ccr.com/wp-content/uploads/2020/06/Version_210_ENG.pdf) saying it does not pass CE specification when oriented head down (and my dive yesterday had been crawling through rocks head down on a JJ, that was, err, fun).