I'd be willing to beta-test a ALVBOV on my rEvo or at least would be interested to hear about such a test and detailed report about it.
A report on it will be very interesting to see. As will a third party supplier suppling off the shelf CL fittings for the rEvo to get rid of the stupidly narrow and straight fittings that they currently have. Which forces the breathing hoses into the wrong direction and jacks up the WOB.
The problem I see is that OSEL doesn't for a start answer requests for info. I have asked about their mushroom valves in the past (using their online information request form) and never received an answer. I bought the new rEvo valves in the meantime.
The first problem you have is to the best of my knowledge OSEL to not have an "online information request form" - email
sales@opensafety.eu direct and if you do not get a response within 24hrs PM me an email address so I can chase the issue for you.
Just to clarify the reason why I am not currently using a BOV, which I suppose is the reason why a lot of rEvo users don't: when trained on a unit, you are instructed (if not ordered) to no modify your unit for the first 50 hrs while you get used to diving it. I am well past 100 hrs on my unit, and still feel like I have to learn a lot about its quirks, and adding an unsanctioned bit of kit is not something I want to do without serious thinking, especially since my diving is currently not putting me in situations where I expect to run into issues of overbreathing my unit for instance (I take my scooter in all my "deeper" dives in any case).
See post from Andy_Del
As to the failure of your manufacturer to supply a critical bit of safety kit***8230;. sorry mate, no comment.
Once I reach a stage where my diving becomes more challenging (deeper, essentially) and I expect WOB to increase substantially, I will start looking into this seriously again. And not just in terms of BOV versus DSV, but indeed in terms of WOB.
See earlier post by GLOC. You can ***8216;fix' the WOB v depth issues with He. Knowing the WOB of your BOV and unit in advance, just lets you plan better or buy the right tool for the job in the first place.
I was initially obsessed by the lack of BOV like a lot of new rEvo users I suppose and I unlearned this obsession by surviving each and every dive I have performed since without one. This doesn't prevent me from reading stories about CO2 hits very carefully, but as I pointed out earlier, not to reinforce my former obsession, but instead, to understand the root cause of those hits and what can be done to prevent them.
Until you don***8217;t survive the dive like others using the same unit and it***8217;s brushed under the carpet***8230;..
BTW, what's missing in most of these theoretical discussions on WOB is that it depends a lot on the diving conditions. A machine test is fine, but you can always put yourself in a real diving situation where you are well past the testing parameters of your unit and even the best unit will come short and make you run out of breath, CCR or OC. Part of getting to know your unit and becoming a good diver is to learn where its "flight envelope" resides. If you try to loop the loop on a Cessna, you might not live to tell the tale. Same on a rebreather.
Sorry Mate, but your BOV or Rb***8217;s WOB is a fixed constant that comes into your core knowledge about the performance capabilities of the kit before you even think about getting it wet. The diving conditions may or may not require better kit, but the whole point of doing unmanned testing before manned testing is the the unmanned envelope exceeds the manned limits.
Would you plan a flight in an experimental Cessna not knowing the fuel usage in advance?
In summary, it is perfectly fine to dive a rebreather without a BOV, as long as you stay within certain diving parameters.
No!
YES! Having a BOV is a good idea. It is not a PTA to maintain, but IF you ever need it in anger, you will be a happy chappy. Forget your OC prejudices, and just think through the possibilities: needing to bailout with loss of breathing control. Would a BOV help? the answer is yes.
Great summary of the bare basics.
Next folk will start to think about it a little deeper and realise that BOV A does not equal BOV B and so on***8230;...
You well have the best BOV in the world, but if it flows wrong way for my unit I wont be buying one
Mark, why is the gas flow in your unit the orientation that it is?
Unit wise the APOC is only available in MCCR
Currently, yes.
You can also buy it with out elecs to do with whatever you want. AFAIK there is at least one SW driven eCCR***8217;d Apoc kicking around.
and it has a lot of bad press to overcome.
Irrelevant if you either want or need the level of performance available.
You can***8217;t get it anywhere else!
Then look at the type of people who choose to dive a MCCR and ask your self if they are the sort of people who would chose to buy a unit with expensive ready made scrubber refills.
Yes if they want to an ALARP unit with the lowest WOB. See your earlier caustic cocktail comment. Don***8217;t want the extra safety features and scrubber duration, don***8217;t use the EACs.
I have dived the APOC and can confirm its a perfictly good unit. Very good in some ways, but it has a bit of a mountin to climb to overcome the bad press
Mark, Great images, thank you for publishing them. Can I forward your images to OSEL for them to use?
As for as the bad press, how much has been deliberately generated by those who can***8217;t meet it***8217;s standard? The gulf in the BOVs performance from the next closest competitor to use the word loosely, is but a case in point!
You don't have a L-R BOV so instantly anyone with that direction rebreather cannot consider your BOV so must buy whichever they consider best from the ones that do fit.
Yup, hence me pointing out that the WOB of the L-R BOVs is comparatively crap, where even known***8230;.. Me thinks a few users might slowly start to figure out that perhaps they could have better***8230;..
I would like the option of a good L-R BOV. However, until those supplying L-R BOVs start to do so, with good published performance, I won***8217;t be buying one! A bit of diversity in my rebreather options would be quite nice.
"Some" I take some as Less than Most
IMO Most RB divers have or want a BOV and WOB is an issue, we have 10 different CCR in my circle of divers, I am the only one without a BOV (because I dive L-R loop and none meet my criteria yet) So that's 90% can't buy your product even if they wanted and 10% have a alternative.
How many of those 9 divers have asked their respective manufacturer why they were sold a BOV they do not know the WOB of?
I say it again- build it, sell it and see- until its in the webshop (to be honest I couldn't even see the R-L BOV for sale at the moment?) you will never know.
R-L ALVBOV has been available for quite a while. It is in the spares section, 2nd page. Considering it comes with hoses etc, has the highest performance and meets CE for both OC and CC use to 100m, the price is highly competitive.
That is IMO unfair- "most" divers aren't on forums so may not know of the alternatives and buy what their manufacturer offers, build it, advertise in magazines and to instructors and people will buy it if it is better.
So, why are ***8216;their***8217; manufacturers NOT offering a better or comparable product?
I know full well that the Apoc and the ALVBOV do not suit everyone. It does however provide a comparison for folk to know what is achievable if your supposedly life support rebreather is professionally engineered.
IMO Pushing the "you can ditch your ADV" line also won't help either- many divers cannot or would not remove their existing ADV's so my advice to OSEL if they want to make a buck is sell a straight up 3rd party replacement BOV in L-R, I wager you will sell a good amount. Leave the ego and WOB bashing at the door and advertise it as the best, lowest WOB BOV and see what happens.
The inclusive ALV is a side effect of the need for the ALVBOV to meet the CE standards required of OSEL***8230;.
At moment one can***8217;t partake in WOB bashing in comparing L-R BOVs as we as a community know feck all about their comparative performance. As more see it as not just minutia; but, critical and potentially life saving knowledge we will probably learn more.
But that is not the Average customer, I would suggest the typical BOV buyer already has a unit, possible with a BOV and the total value of their unit is less than £4000 second hand, the BOV market is for an accessory not whole units.
Agreed. Most good units come with a BOV as standard. If it is actually any good is the unknown.
If what is supplied as a standard bit of kit is good, do you need to change it? Again, comes down to that critical line were the knowledge of how low your WOB has to be, needs to known.
BUT- There is
nothing for me to buy- no L-R BOV as 3rd party replacement for my existing rebreather and you have no off the shelf CCR I can buy (That's my personal problem, I don't want to buy Another rebreather I have to modify to work, this one took enough effort!!
Why bother supplying a BOV for your L-R breather, there is insufficient a market, for a BOV of known performance.
Why is your breather L-R?
and old chestnut, but if there wasn***8217;t an off the shelf CCR to buy, what is Mark Chase wearing in the above pics! No modification necessary***8230; to get the best performance available! The ergonomics and weight out of the box aren***8217;t to bad either.
I am probably like alot of divers, I have an old Inspiration that highly modded but essentially worthless (much less than £2000) I would consider a reasonable BOV, 2nd hand AP and Shrimps are £250-400 depending on condition, I understand WOB's importance and the risk of CO2, should I invest a small amount and risk a worse WOB in one scenario but potentially protect against a Very bad thing or change my entire unit because the accessory I need is the Wrong way around? ;-)
Money talks, a BOV costs the same as a whole years diving, even for those with big pockets its an investment and they will do their research.
So, you know that the standard Inspo DSV and probably the OCB has a WOB of around 2.13J/L. Your ***8220;alot of divers***8221; are the few folk, who on going to a Shrimp at 1.44J/L will know that they are lowering their units WOB***8230; Polar opposite of the JJ guys.
You will still have no idea of the OC side of the WOB but that appears unimportant, or else folk would be demanding to know it before shelling out their hard earned cash.
This lack of community knowledge tells me folk are not doing their research.
Ditto, Mark- I would be very interested in a more detailed opinion (those pics and your thoughts deserve their own thread)
Agreed.
and before folk demand it happens, OSEL have offered to advertise on this forum to support its costs***8230;.
Do you have any data on real world flow rates of BOV's? I suspect that the difference at around 20 l/m but not be as big as at 75 l/m, and I don't think it will be a linear relationship.
Mick, mate most BOV***8217;s have no testing done on them, or if any it is single point at best, so your pretty much screwed if you want real world data off them for comparison purposes.
When testing is done certain fixed flow rates are used and you can read about these straight out of EN14143 or EN250, for the respective CC or OC requirements.
As I understand it, the difference remains the same ratio between BOVs no matter the flow rate***8230; No different to complete rebreathers. it is why WOB is done at 75lpm but scrubber duration at 40lpm. Importantly however, if your having a CO2 issue, you won***8217;t be at 20lpm***8230;. at least not for very long!
The rebreather I dive has it***8217;s WOB published openly across the entire range of flow rates, if you want to see what this looks like going from 20lpm to 90lpm? Possibly very useful for those with Shrimps as the entire units WOB is the same as the Shrimp BOV by itself at 40m on Air at 40lpm***8230;...
