Because the "first best" you are hinting at is not designed for use with most recreational rebreathers due to having the gas flow direction arse about face. So this is like comparing the finest jump race horse with the finest racing camel - they can't be compared in much of any meaningful way as they won't ever be competing against each other.
So why not require the BOV you buy have the same WOB as it? Both you and any BOV supplier have known for years that it is achievable.
Oh I agree entirely. Only we should discount rebreathers that are designed for an entirely different market (like yours) as out of scope as they are no more relevant to the vast majority of recreational rebreather users than the air recycling systems on a submarine. It could have such the best work of breathing physically possible... but as it stands today, if you cannot use it, it is useless.
The Apoc works fine as an mCCR as sold by OSEL for use to 100m and beyond for the recreational diver market that it is aimed at. Is also a great eCCR but they aren't selling that functionality yet. Just cause it is designed (over designed really for the recreational market) with more rigour than most doesn't exclude it: especially noting the subject of the thread. Something it was specifically designed to cater for: hence it's lowest WOB in both CC and OC modes!
i.e WOB of "bare unit" + WOB of DSV = total.
I understand unfortunately that it is not quite that simple, though there is a linear correlation I believe. i.e.. the total WOB isn't quite a sum of all the parts; rather a meld.
Would you PM me the report?
I'd love to post it, but I acquired it through an unusual route and am under NDA with the company in question. I also have personal reasons for not doing so as I don't agree with most of the authors assessments and conclusions. However I suggest that you have a chat to the guy that flogged you your rb and 2020 fixes to see if that shakes loose a copy. The testing in question was done 24th July 2015 and the report finalised 02/10/2015 if that assists.
I suspect you have seen the Golem reports before, but I have pasted them below FYI.
Thanks Matt. Don't recall having seen those particular results but they suggest that the older GG BOV actually had a better OC WOB than the new one: if the above report is to be believed.
For once we fully agree. I think that the CE standard should include reporting for the WOB for the unit and mouthpiece (all modes), along with the tested endurance figures.
It already does!
Depending on the specific manufacturers/notified bodies interpretation and if you take the easy route or the harder route. Open disclosure of the testing that is scientifically fully repeatable being the harder option! DL had to do it to meet the EN61508 requirement and for the FMECA and design validation. Hence this including the WOB of not only the Apoc but also its BOV compared to numerous other DSV/BOV options and its tested endurance figures to a selection of temps/depths/workloads.
Isnt an Apex ATX50 thats simply at 90 degrees to the mouthpiece? It seems odd its failed so badly? But I reely cant feel it in actual use. It seems to breath as easy as my Apex OC regs. So spin the reg through 90degrees and stick a mouthpiece on it and its one of the best performing OC regs I know?
Which is why you do unmanned testing to verify it and if it doesn't come up to scratch keep up the R&D until you get the same result (or better) than that which you are copying.
At a guess your Shrimp's mouthpiece bore is too small noting the greater separation between the mouthpiece and the OC gas inflow: compared to that of the original reg. Redesign it to take the OSEL mouthpiece and tweak the angle to replicate that of the ALVBOV (which isn't as 90' as disclosed in the FEMCA) and your probably going to notice quite a change. After that it is a case of smoothing the internal flow and no different to blueprinting an engine block.
Coz your BOV flows the wrong way for my unit or as you know (coz I wanted to place an order) id buy one
As discussed before, so what:
a) what is the effect on your unit of reversing the flow? Is it better or worse? More safe or less safe?
- How high a priority for you is the topic of this thread? If #1 then you need to build your CCR choice around a BOV that actually meets this criteria and not vis versa.
b) why haven't you demanded proof of your BOVs WOB results before purchase? Add up how much you have spent on BOVs over the years!
If its negligable below 40LPM that will do me but I see the benifit of it being even better dispite the fact A: I dont use air and B: If my SAC went that high I am probably going to die anyway reguardless of what BOV i had.
A: You can duplicate the gas density of Air with mixed-gas, you just have to be deeper. Same result!
B: Have a gander at
www.hse.gov.uk/research/rrpdf/rr1073.pdf Spiking your RMV for a short period shouldn't be sufficient to kill you: at least not until you run out of gas.... This argument reminds me of
http://www-personal.umich.edu/~jlawler/aue/sig.html
Bail early enough and at a low enough RMV with a lower WOB OC BOV and your going to use less gas through having a lower RMV. Even if you have a higher RMV for 15min, if your OC deco is planned for 2hrs and has some fat as a buffer for your SAC, the time where the higher bailout RMV is an issue is only a fraction and the average inc during deco is lower that the peak.
Last count it was two deaths on the KISS?
1 Pre-exisitng heart problem diver died on the surface, two diver got lost inside a cave on his first ever dive on a KISS
Not too bad for a unit thats been arround for 17years
I count 8 KISS unit fatalities not including the one from a couple of days ago in New Mexico. A few of those might be other units but shrug.
No and I thaught it was an excelent BOV but sadly when I asked for one that worked on my JJ they couldn't supply it.
Bonus points to JJ/Dave et al for this judgement call. Wish we saw this more often.
If the kit isn't up to scratch why risk diving it?
I suggested you cant compare the CC WOB figure with the OC WOB figure when making the statment "comming off loop on to a OC reg with a higher WOB is an issue"
Why not? You should know the total loop WOB of the RB and the OC BOV of the BOV!
For example the Apoc loop WOB is 1.44J/L at 40m/75LPM/Air and the OC ALVBOV is 0.87J/L at 50m/62.5LPM/Air.
Now it would be better if the criteria were both the same for EN14143 and EN250 to allow direct comparison but you would need to ask MP and PR amongst the others who sit on the CEN committee who wrote just recently re-wrote EN14143:2013 as to why this is not the case. At the moment something is better than nothing and they are at least comparable: depth v RMV trading off against each other.
Knowing the CC mode WOB of the BOV/DSV just helps you competitively compare these against each other and tells you if you are raising or lowering the WOB of your unit. Anyone know the WOB of the rEvo or Mk15 DSV for example? and I can tell you how much higher it is than the ALVBOV.
The OC WOB figure is prety much line in the sand for the BOV.
Yeah, agreed, this tells you how much use it is as a BOV. Tis telling that there is only one BOV on the market with both the CC and OC WOBs published.... I would much rather all be published and all comparable to those offered by the ALVBOV. Not a commercially sound opinion perhaps but one safer for all concerned.
The CC WOB figure depends on loop design, scrubber medium, scrubber packing, CCR position on the body, Orientation etc etc. The BOV is only one part of the equation.
Granted. BUT the BOV/DSV CC mode WOB is the major factor in this equation as a brief comparison of units WOB and their DSV/BOV WOB shows:
Inspo 2.99J/L odd // Inspo DSV 2.13J/L odd
JJ-CCR 1.8J/L odd // JJ-BOV 1.06J/L
Apoc 1.44J/L // ALVBOV 0.57J/L
I dived a KISS on 5Jl for ages without considering it an issue so I am very happy with my KISS running 1.5Jl with a Shrimp
Just cause the Shrimp might have a CC WOB of 1.5J/L doesn't mean your entire KISS will have that same WOB. Unless all other components supported such a low WOB its total WOB will quite likely be significantly higher! For example what is the WOB of the Classic as sold now with the Hollis BOV fitted?
Yes posably but I am considerably safer on the Shrimp BOV than i was on the JJ BOV
Not CC as that is now higher!
Only potentially OC, as we don't have the JJ-BOV's OC WOB to compare to the Shrimps! EN250 only needs it to beat 2.5J/L and based on the testing I have seen the Shrimp hit 3.23J/L at only 50.5LPM at 50m odd. If the JJ-BOV had similar WOB (still outside EN250) but functioned at 62.5LPM, it could be argued that it is actually considerably safer.
I may have lost somehting on CCR WOB but I gained a LOT in terms of OC WOB and dryness and reliability
How much is the LOT actually?
My JJ was wet to breath which scares me a lot due to water vapor inhilation issues and the WOB at depth was awfull
Saltwater asphyxiation does suck. My experience from a dodgy OC reg and the subsequent medical treatment/observation makes me agree with you.
That would be interesting. The Hollis and Poseidon BOVs were not available when I baught my Shrimp 6 years ago
and if both published their WOBs for OC and CC modes you wouldn't even need to get wet to do the comparison. As both are sold on CE'd Rbs thats at least a start..... Unlike where you are at the moment: at least as far as the OC side of the bailout argument goes. Something to think about.
