I have been around long enough to know how auditing and certifications should work and the games some people can play. I asked a question to test the process and the response (or lack of due process follow-up) speaks volumes about the whole system. This is most likely not just an APOC-specific issue.
Tony, valid points. I wonder if SGS were still smarting at the time from being put through the wringer by UKRS when the Apoc's cert process got their butts out of a fire over a different units CE.
So does that mean that the idea is CE approved, but the production units may not be....
Interesting concept except OSEL had to produce the units to get them CE'd. I understand and correct me if I am wrong but AFAIK the Apoc that got through the EN14143 process was unchanged from the production spec despite years taken. The 61508 process however has seen numerous functional safety improvements incorporated and the production spec as shipped upgraded as a result.
This refers to the earlier 5.5 lbs scrubber rather than the eventual 6 lbs one. The effective bed depth with the radial design was such that they got premature breakthrough - I think the duration almost doubled with the addition of the extra 250 grams of sorb. I dunno if I'd describe the prism scrubber as awesome, but it's pretty good...
EDIT: on reflection, the scrubber sizes might be 5 lbs and 6 lbs respectively... which would make more sense.
Mike, Thanks, I wasn't aware of the details.
Compared with ~5 hours at 1.3 lpm and 18m depth for the Prism.
~400 litres of CO2 absorbed until PPCO2 of 0.5 on the Prism
~260 litres of CO2 absorbed until PPCO2 of 2.0 on the Apoc.
I'd take your bet
Cool, lets see what they publish once Hollis sort out their CE delays. If we are going use 0.5 can we use the second time the Apoc breaks through that rather than the first or split the difference and use 1.0
I'm not arguing that Apoc + N@90 Pod + Shearwater isn't just fine - I think it is. What we are talking about is testing and certification. Apoc as above with monitoring is not tested. It is not certified. You cannot buy a recreational apoc that is certified to dive deeper than 6m.
Its certainly certified and tested, I am just not sure the testing is public. You might want to hit up DL or NA90 for a copy of "IMPACT ASSESSMENT OF FITTING NARKEDAT90 OXYGEN CELL HOLDER TO APOCALYPSE TYPE IV REBREATHERS"
You're probably right about the life insurance thing, so let me put it another way.
I can dive the Prism in a CDAA controlled site as it is a commercially available, unmodified unit.
I cannot dive my apoc in a CDAA site as it is not a commercially available unmodified unit.
Whats the exact definition of unmodified and commercially available? The Apoc is designed to have pods screwed on so you not modifying anything and the pods and elecs are commercially available.
You buy Apoc commercially available unmodified from one seller and you screw on electronics from a second that are commercially available unmodified. Cause if you can't dive a rig with add on parts from a second manufacturers that would rule out most offboard gas solutions, BOVs, wings, backplates and 4th cell setups....
But of the two units I have sitting in my garage, the Prism is the only one that has had all components tested in the configuration that I dive it. If you want a comprehensively tested rebreather that you can dive deeper than 6m, as you say you do, then the Apoc doesn't meet that criteria. But others do.
As above, you might be surprised what has and hasn't been tested.
No. And how could I possibly find someone who would have ordered a product that did not exist for general sale?
Excluding the customer well company who bought and dived those rigs, buggered if I know but your telling your story, I am just trying to help you with the facts.
As you well know, the flaw was the attempt to directly measure end tidal CO2 at the end of a large exhale hose, which we proved was unreliable. This finding was published in a medical journal. Alex changed the method after that. It is there in black and white in the thread I linked to.
IIRC Alex agreed with you that they couldn't have got what you cobbled together to work reliably either....
AFAIK I haven't seen anything published by Alex/Dl/OSEL where they have flagged any change in the method of measurement for the CO2 in the Apoc or change in how this is done. I have seen Alex post more specific detail about how it was done after finding the flapper valve bypass issue as a means of disclosing discovery of the issue as required of them by their 61508 process.
Uncharacteristically imprecise of you to previously report a reading when the unit was not being breathed, or are you just changing your story now? As to the rest of it, the normal end tidal CO2 is ~5 kPa +/- 1kPa (2 SD) with a known tendency for it to rise during diving. Thus, 4 is unexpectedly low and high 5s would be more like what I would expect.
The Apoc is user calibrated to the divers resting end tidal exhale during pre-dive setups which is what it displays. I am presuming that takes your above into account but am interested in what you and how you test this.
There are no data of that nature across a range of tidal volumes in that report. If you think there are, then please post page and paragraph / table / figure number.
Data no, reference to there being so, certainly page 4, 2.Background, 1. CO2 Monitor Unexpected Alarms, as you get a range of tidal volumes when you dive it. What you probably want is this report which also covers the different tidal volume measurements DV_End-of-exhale_CO2_0405017.pdf which is referenced on page 7.
http://www.deeplife.co.uk/or_files/Fault_Study_CO2_Bypass_110314.pdf
This is just testimony to the accuracy of the CO2 sensor itself which has never been in dispute.
That is the accuracy of the CO2 monitor. Like you found a CO2 sensor by itself at the end of the breathing hose doesn't do much. Read it again, its the sum of the parts which has the accuracy not just an element.
Luckily no one died because the divers noticed the manual add valve was stuck open. I think "life threatening" is a fair depiction of a stuck open oxygen addition valve at depth.
Simon, re-read the OPs report of that 53m dive. What is exactly life threatening about a constant 10lpm oxygen flow on ascent that you are fully aware of and can feather the valve? An embuggerance sure, life threatening, really!
IIRC part of DLs testing process was testing other MAVs and I understand some of these got upwards of 200lpm oxygen flow when they stuck on which I agree is more of an issue and cause for concern.
The point is Brad's incessant ranting about the importance of CE certification and the absolute imperative to dot every i and cross every t in this regard, but then it is apparently OK to dive the oxygen Apoc uncertified after modifying it. Breath-taking hypocrisy.
How is an Apoc with the same tested elecs as fitted to other rebreathers that meet CE uncertified after a PPO2 monitoring pod is screwed onto it? You can't have it 2 ways!
A shearwater NERD on a pod and the BIO350 monitor is looking like an interesting mCCR setup.
I couldn't give a monkey's if every i isn't dotted and t isn't crossed, it would just be nice to know which i & t has and hasn't been dotted and crossed or achieved for life support equipment as part of the buying decision process.
I find it interesting Simon that the couple of reports of purge buttons on an Apoc coming off are a major issue for you cept that occurring in other rebreathers appears accepted as just normal
http://www.rebreatherworld.com/bail-out-valve-aka-bov/47496-golem-gear-shrimp-2nd-stage-reg.html and user pays.
Regards
Brad