co2 hits? bov or not

[Michael Thornton]

The CE tests were done at 50m as the published data shows. The CE'd Explorer it is attached to is rated to 40m because it uses a minimum nitrox gas of 32%.

Next he will claim the BOV can't use anything less than 32%. I just finished catching up on this thread and had to take a pepto it was so nauseating.

I for one am happy with my decision to use a BOV. I think that if I ever have a CO2 issue I will be thankful for my decision. If I go another 14 years without one I won't be upset that I have had one on my unit.


Sent from my iPhone using Tapatalk

 

[lizardland]

Matthew, some in the dive community are actually interested in elements that are attributable to improved safety.

Like selling an oxygen rebreather with no requirement for training that you encouraged users to add aftermarket kit too to make it diveable?

That must've been a hell of a risk assessment.

 

[WFO]

How can they get away with that whereas AP want to see your blue peter badge before they'll sell you an O ring? My take on it is "I'm a grown up, sell me what I want and mind yer own fookin business what I'm doing with it"... but since it was deas that seemed to start the whole "sue everybody selling ccrs" trend it seems a bit odd.

 

[WFO]

Correct.

You can see a cutaway image of the number of injection molded parts that retooling would needed for in this simple image https://www.facebook.com/1512989548...1298954899613/174849205877921/?type=3&theater

Back on topic.
So Simon says, the recommendation is that - as guidance only - not locked in stone, as other subjective factors also play a part. Divers should only consider purchasing rebreathers and BOVs and regulators (aka UBA) if the WOB on Air is known to be below 1.5-2.0J/L, correct?

Cheers for the pic, that is actually quite cool and shows a bit more work has gone into it than some of the other units which are simply "revolved cut" and can be done in one milling op.
If you spent more time on the actual physical engineering work done you might get a bit more respect for yourself and that jeb end you work for instead of playing word games and picking holes in other peoples.


I think you're reading too much into that 2.0J/l number, or taking the piss, probably both. WOB was given for the working conditions, the moral to take from the story would be to make sure your application results in <2J/l, whether that's air at 50 or mix at 75 or whatever.

 

[Brad_Horn]

The CE tests were done at 50m as the published data shows. The CE'd Explorer it is attached to is rated to 40m because it uses a minimum nitrox gas of 32%.

Matt, Unless I have missed something you have only released the OC WOB figure for the Hollis BOV in White Explorer guise. Black being different and unknown due to hose routing variation. So yes, it is to 50m like every other reg measured for EN250. No surprise there.
Without the individual BOV CC WOB data all that a customer has to go off is that the maximum WOB of the Explorer exceeds the limit at 40m. Diving it on another rebreather in CC mode any deeper than 40m means any performance is unknown.
Still means that anyone going from a APD OCB to Hollis BOV is upgrading their BOV as they now know the OC WOB for bailout at 1.1J/L, is very good as opposed to only just meeting EN250 limits.

4:20 to 5mbar breakthrough according to the NEDU tests. Is your 5 hour quote @ 5mbar or 20mbar? IIRC yours is to 20mbar, so its not "like with like".

5mbar to 5hrs. Dropping the CO2 flow and raising the temp, really extends the duration, which is I presume why Hollis only give that data.

The 20mbar data is used to give the 2:45min (at the mouth) recommended maximum scrubber duration for a surface to surface dive to max 100m under the higher CO2 flow and colder CE test criteria.

My take on it is "I'm a grown up, sell me what I want and mind yer own fookin business what I'm doing with it"...

Your the customer. It is your unit. What you do with it once received is out of OSELs hands. OSEL have done everything in their power to ensure it meets every single CE standard requirement, inclusive of EN61508, which requires it to be functionally safe. You want a spare part for an Apoc, just order it direct. You want training, get it from an instructor with the experience to provide it.

but since it was deas that seemed to start the whole "sue everybody selling ccrs" trend it seems a bit odd.

You will if you do some research, actually find this is an interesting myth, created by those with an agenda who it serves well. AFAIK all Alex has been is an expert witness on two court cases against APD at the request of the widows and the technical evidence that he tendered has never been technically disproved. ie. with what he has published you can take that and test a unit with it and find he is right. You can read more about it at http://crossbowdiving.com/barrett
More on the history between the players dates from back in 2000 when Alex found his Inspo had been designed to recalibrate at about 50m. http://www.deeplife.co.uk/files/Deep_Life_Press_Release_101130.pdf

Cheers for the pic, that is actually quite cool and shows a bit more work has gone into it than some of the other units which are simply "revolved cut" and can be done in one milling op.

Exactly. Which along with unmanned testing to verify, is what needs to be done to offer users high performance kit.

I think you're reading too much into that 2.0J/l number, or taking the piss, probably both. WOB was given for the working conditions, the moral to take from the story would be to make sure your application results in <2J/l, whether that's air at 50 or mix at 75 or whatever.

As Simon cited, 2.0J/L is the maximum recommendation, the better or even more safe, lower end is 1.5J/L.

I would only be taking the piss if I challenged someone to plan a dive to 100m, and the requirement was that you had to know your WOB remained below 1.5J/L at all times on the dive! Doesn't matter the gas used as long as it is breathable, so the lowest density Heliox is fine. You can do it on an Apoc as you know pre-dive that your WOB in both OC and CC modes will be less than this.
It is taking the piss that even raising the bar to 2.0J/L, and you can't do it on ANY other rebreather that is fitted with a BOV! (unless it is a rEvo III or Mk15.5 running an ALVBOV).

How can folk know application of their BOV in anger results in <2.0J/L, if they have no idea of its performance in both CC and OC modes? Quite a serious question.

 

[Mr fish]

More on the history between the players dates from back in 2000 when Alex found his Inspo had been designed to recalibrate at about 50m.

LOL back in 2000,

Maybe it was a special unit just for him , as the fooker had no clue how to calibrate his unit be4 the dive , as we have seen from his post on the matter over at RBW ,:thumbsup: http://www.rebreatherworld.com/showthread.php?2382-Can-this-be-clarified

2005 be4 the red head was put right , its a Miracle the guy didn't make it on to his own ccr death list , would he have made guru or noddy on that list ,


id bet noddy but IDIOT SAVANT would be no the money

 

[PeterN]

Too many numbers and too much "science" here.

What this thread needs is some good old first person anacdotal "evidence".

I dove my unit with a DSV for aprox 150 hrs. I then affixed a Golem Shrimp for aprox 100 hrs. I have since switched back to a DSV.

Just prior to ditching my Shrimp I did a test. The real kind of test where no one else was there and no instruments were involved.

I dove to aprox 100 ft shrimp equipped. I then repeated the dive DSV equipped. I put the Shrimp back on and tried again. Air dil.

The difference was quite clear. Nothing subtle about it. The DSV breathes notacably better. Also at 200 ft the OC side of the Shrimp compares poorly to my 20 year old Poseidon's.

The shrimp is well made and easy to use. I very much liked the bayonet connections that made cleaning and inspection a snap. I think the mushroom valves on my DSV are better. I think the OC internals on the Shrimp are only ok.

One of my principle cave diving buddies pointed out the other day that there are conditions where a BOV is highly advantages. He tells me of a very high flow cave in the States where they are working hard in the extremel to pull themselves down hand over hand to get past a restriction that causes the flow to get off the chart. He points out that doing anything more than pulling in that situation would be death defying. Fair enough.

I have been present and may have saved the life of a diver who had a full on CO2 hit. He went from fine to being hidden behind a wall of bubbles in seconds. He sucked dry his BO and much of mine in very little time. Had we not been relatively shallow he would died. However he was in horrible shape and was milking his sorb. I believe the technical term for him is that he is an idiot.

As for me, I have been swapping second stages since the late 80's. The plumbing of my rig particularly with hypoxic gasses is not only much simpler but I believe it to be safer.

I would never encourage anyone to follow my lead. I do however think that many divers substitute gear for proper procedure and practice. More gizmos, cells, regs etc do not in themselves make for better safety. The correct gizmos and well practiced procedures do. In my not at all humble opinion.

I expect that this will settle the issue. ;-)

Peter

,,

 

[Mr fish]

I expect that this will settle the issue. ;-)

Peter




Yes it has, Thank you :thumbsup:


I just look at it this way , after years of sucking air through a straw at 70m, I think iv got it good with the kit that's about these Days,

some c7nts are never satisfied tho , :naughty:

 

[Peter L]

I would never encourage anyone to follow my lead. I do however think that many divers substitute gear for proper procedure and practice. More gizmos, cells, regs etc do not in themselves make for better safety. The correct gizmos and well practiced procedures do. In my not at all humble opinion.

I expect that this will settle the issue. ;-)
,

"You must spread some Reputation around before giving it to PeterN again."

Flawed logic is always a better read than an argument over semantics but that being said a well prepared unit with good pre-dive checks trumps any amount of alarms and detectors.
The problem is that the primary flaw is the unending capacity for divers to scrimp 'that one last dive out of this sorb or cell or battery or yada yada yada'

 

[Simon Mitchell]

By not focusing on the BOV aspect of the thread, you have deliberately taken your response to misguide folk and mis-direct attention of the thread down the Apoc route, which I am sure those that make particularly poor performance BOVs (like that which you dive) will be very happy with you for. Is mitigating a products poor performance by having to use high he mixes through it really the solution or should you just get the manufacturers to provide low WOB kit upfront!

Brad,

Going down the "Apoc route" is entirely relevant to this thread because your position appears to be that since the Apoc is the only rebreather with a WOB that allegedly meets recommendations under all plausible conditions, it is the only rebreather that should be used, or at the very least the others should be judged adversely for meeting a lower standard. Pointing out that there are many factors that go into choice of rebreather and BOV, and that there are many reasons why divers may not wish to choose an Apoc (which include the fact that at least one of the features that results in a low WOB may have disadvantages) is entirely relevant to the discussion.

Simon, both of your quotes are quite true. It is just something that you need to approach with an open mind.
1) You can buy an Apoc for a very low comparative cost and fit whatever elecs you want to it. Fact.
2) Alex knows that most eCCRs that are available, have design issues, so does not want Apocs sold as eCCRs with those electronics. Fact.
Not sure what is difficult to understand about that.

You are really stretching the limits of creative writing here Brad. Alex meant nothing of the sort, which if you go back and read the original thread is plainly obvious. He was directly contradicting the idea you are floating, but at a time before it became commercially necessary to sell as many O2 Apocs as possible. There was a time when you were going to need training to buy one as well.... that too has gone out the window now that you don't have an iCCR and need to sell lots of O2 units. Your focus on one favourable test characteristic of your unit is understandable (and in that regard I don't disagree with everything you as saying as I have previously stated), but proselytising about safety and being critical of everyone else in relation to that characteristic looks a bit hypocritical when you look at the big picture.

Simon M

 

[Brad_Horn]

What this thread needs is some good old first person anacdotal "evidence".

I dove my unit with a DSV for aprox 150 hrs. I then affixed a Golem Shrimp for aprox 100 hrs. I have since switched back to a DSV.

Just prior to ditching my Shrimp I did a test. The real kind of test where no one else was there and no instruments were involved.

I dove to aprox 100 ft shrimp equipped. I then repeated the dive DSV equipped. I put the Shrimp back on and tried again. Air dil.

The difference was quite clear. Nothing subtle about it. The DSV breathes notacably better. Also at 200 ft the OC side of the Shrimp compares poorly to my 20 year old Poseidon's.

The shrimp is well made and easy to use. I very much liked the bayonet connections that made cleaning and inspection a snap. I think the mushroom valves on my DSV are better. I think the OC internals on the Shrimp are only ok.

Exactly.

Which just means if you knew the unmanned performance figures for BOVs before purchasing them; you could select the one best for your need. ie. one with an equal or lower CC WOB than your DSV. And obviously a BOV with comparable OC WOB to your Poseidon regs. It is not rocket science.

Going down the "Apoc route" is entirely relevant to this thread because your position appears to be that since the Apoc is the only rebreather with a WOB that allegedly meets recommendations under all plausible conditions, it is the only rebreather that should be used, or at the very least the others should be judged adversely for meeting a lower standard.

Simply BS Simon. Yes the Apoc meets your cited WOB requirement, actually exceeds it by some margin. It should do, WOB that was ALARP, was a design requirement. So why the hell do other rebreather NOT meet this simple need?

You have cited it BUT obviously do not believe it is something necessary, based on your chosen rebreather. Why not?

I do however agree with you in that other units should be judged for failing to meet the recommended WOB that you cited for diver safety from the POV of their WOB. 20 years ago they figured out it needed to be done in order to directly compare OC regulators yet you cannot do that with rebreathers! That is pretty poor.

Pointing out that there are many factors that go into choice of rebreather and BOV, and that there are many reasons why divers may not wish to choose an Apoc (which include the fact that at least one of the features that results in a low WOB may have disadvantages) is entirely relevant to the discussion.

Considering the thread is about BOVs kinda takes the relevancy out of your argument. Sure the Apoc comes with the highest performing BOV available but that is about it.

I am curious though Simon, what are the disadvantages of low WOB in OC and CC modes, for a BOV?

He was directly contradicting the idea you are floating, but at a time before it became commercially necessary to sell as many O2 Apocs as possible. There was a time when you were going to need training to buy one as well.... that too has gone out the window now that you don't have an iCCR and need to sell lots of O2 units.

Really Simon. What makes you think that OSEL has ever needed to sell lots of O2-CCR units? They offer them, they do not need to sell them. Subtle difference.
DL had a working eCCR long before the iCCR was designed in order to meet EN14143:2003 requirements for recreational sale and use.
If other manufacturers had not watered down EN14143 in 2013, you still would not be able to buy a mCCR Apoc from OSEL. That was a freebie commercial opportunity that enabled OSEL to directly compete in a market with others and offer a higher performance product, for less.

Your focus on one favourable test characteristic of your unit is understandable (and in that regard I don't disagree with everything you as saying as I have previously stated), but proselytising about safety and being critical of everyone else in relation to that characteristic looks a bit hypocritical when you look at the big picture.

Simon, Feel free to suggest another means of non-subjective comparison of BOVs; that is relevant to the divers safety?
Other than knowing the OC and CC WOB. Which the ALVBOV is the only BOV you know this for anyway!

 

[WFO]

As Simon cited, 2.0J/L is the maximum recommendation, the better or even more safe, lower end is 1.5J/L.

I would only be taking the piss if I challenged someone to plan a dive to 100m, and the requirement was that you had to know your WOB remained below 1.5J/L at all times on the dive! Doesn't matter the gas used as long as it is breathable, so the lowest density Heliox is fine. You can do it on an Apoc as you know pre-dive that your WOB in both OC and CC modes will be less than this.
It is taking the piss that even raising the bar to 2.0J/L, and you can't do it on ANY other rebreather that is fitted with a BOV! (unless it is a rEvo III or Mk15.5 running an ALVBOV).

How can folk know application of their BOV in anger results in <2.0J/L, if they have no idea of its performance in both CC and OC modes? Quite a serious question.

The "taking the piss" bit is using resultant "air @ whatever depth" J/l numbers tenuously extrapolated to air data you have on albov to say that this is comparable to someone else' specific case of x/y gas mix at z depth.

They probably don't know this. And are probably reliant on "well it breathes fine" (subjective) and "I'll just stick plenty He through it".

 

[Simon Mitchell]

You have cited it BUT obviously do not believe it is something necessary, based on your chosen rebreather. Why not?

You are confusing the NEDU WOB recommendation with a standard. It is, in fact, a recommendation for WOB in whatever configuration the rebreather happens to be in for a particular dive (which obviously includes gas choice). A standard, on the other hand, is required benchmark evaluated under a specified set of conditions that can be standardised in testing. All rebreathers meet the relevant standards for legal manufacturing in their relevant jursidictions. Whether or not we (you or I) believe that to be ideal or adequate is another matter.

I believe the WOB should be as low as I can get it whilst paying due attention to all the other factors that go into making a dive safe. These include rebreather configuration and functionality and my familiarity with the unit. In the pursuit of being happy with all other factors I am prepared to accept that the rebreather I am diving may not reach the ideal level of WOB for heavy exercise at depth . Problems with WOB are a risk factor that I am able to mitigate (not eliminate) by simply being aware of the issue. I dive several rebreathers in fact, and I might (for example) favour one over the other for deeper diving if WOB is likely to be a greater issue. WOB is one of many potential issues on a rebreather dive, and as I have pointed out previously, the pursuit of low WOB can introduce other problems like the use of scrubbers with potentially poorer performance. While I think that all divers should be aware of WOB issues and be mindful of them when configuring their units for a dive, I personally would certainly not, and nor would I expect other divers to, base their choice of equipment solely on WOB considerations.

I am curious though Simon, what are the disadvantages of low WOB in OC and CC modes, for a BOV?

None obviously. The disadvantages I spoke of related to the use of scrubber canisters that may perform less well than granular sorb.

Really Simon. What makes you think that OSEL has ever needed to sell lots of O2-CCR units? They offer them, they do not need to sell them. Subtle difference.
DL had a working eCCR long before the iCCR was designed in order to meet EN14143:2003 requirements for recreational sale and use.

Here we go again with word games. Whether or not DL have ever had a "working" eCCR is, as you well know, a hotly disputed issue. More importantly, to my knowledge, other than prototypes, neither DL nor any other secondary manufacturer have sold any working DL eCCRs to any wider market.

And, the iCCR is nowhere to be seen.

And you completely ignored the "safety elephant in the room": you are selling rebreathers that you personally invite purchasers to modify in any way they please, to people who may have absolutely no training in diving rebreathers. I think that "kinda" puts safety issues in relation to WOB into perspective.

Simon M

 

[Mr fish]

Have to say I think selling a 02 rig to a untrained diver is More Dangerous than selling a ccr with a ppo2 read out ,

WOB is of no fooking use at 6m when you never got trained on how to purge the o2 rig be4 you jumped in , :thumbsup:


ps
rebreather configuration and functionality and my familiarity with the unit is also how id pick my unit ,
I have one thing/rule I use when buying from or working for never deal with C6NTS ,
so the apox and is so called good but wet WOB is way off the list lol not mention the hair-trigger auto bail out and sticky o2 thing,

 

[Brad_Horn]

You are confusing the NEDU WOB recommendation with a standard. It is, in fact, a recommendation for WOB in whatever configuration the rebreather happens to be in for a particular dive (which obviously includes gas choice).

Simon, quite happy with the difference between the two. What you are saying however, is ignore the recommendation you cited because it only works if your diving an Apoc (and potentially a Mk15.5 or rEvo if fitted with ALVBOV) so needs to be ignored!

Pick any other rebreather. Both configuration and gas choice are irrelevant if you do not know the WOB to a defined norm, in the first place. As NEDU provided testing for your unit, at 100m it is 2.99J/L on Heliox at 75lpm. So what is the maximum depth you can dive to on your unit, with OCB fitted, whilst staying within the cited recommendation? You get my point now.

All rebreathers meet the relevant standards for legal manufacturing in their relevant jursidictions. Whether or not we (you or I) believe that to be ideal or adequate is another matter.

They do? Lovely bit of seaside real estate with ocean views going cheap in Alice Springs as well I hear.

The CE standard for WOB provides a worst case criteria that is just acceptable >> kinda like you grading an academic paper from one of your students with a Pass. Folk should be aiming to have much much better performing kit than that. As I pointed out earlier, they did this with OC regs back in 1996, in order to identify the wheat from the chaff. If the recommendation is that the kit you breath in any configuration with any gas, should be better than 1.5-2.0J/L, you should have that data available.
Talking about BOVs though we are getting a bit ahead of our selves, as you cannot even tell me the WOB at any depth and on any gas of the OCB that you use. If the "experts" fail, what chance is there for the regular diver?

I believe the WOB should be as low as I can get it whilst paying due attention to all the other factors that go into making a dive safe. These include rebreather configuration and functionality and my familiarity with the unit. In the pursuit of being happy with all other factors I am prepared to accept that the rebreather I am diving may not reach the ideal level of WOB for heavy exercise at depth .

At what depth do you - on that unit - exceed the ideal level of WOB and what is that WOB?

Problems with WOB are a risk factor that I am able to mitigate (not eliminate) by simply being aware of the issue. I dive several rebreathers in fact, and I might (for example) favour one over the other for deeper diving if WOB is likely to be a greater issue. WOB is one of many potential issues on a rebreather dive, and as I have pointed out previously, the pursuit of low WOB can introduce other problems like the use of scrubbers with potentially poorer performance.

What unit with low WOB suffers from poorer scrubber performance?

While I think that all divers should be aware of WOB issues and be mindful of them when configuring their units for a dive, I personally would certainly not, and nor would I expect other divers to, base their choice of equipment solely on WOB considerations.

Agreed. But I take it you also agree that they should at least be able to know the WOB of their kit in the first place?

Whether or not DL have ever had a "working" eCCR is, as you well know, a hotly disputed issue.

Little hard to get a non-working eCCR CE certified!

And you completely ignored the "safety elephant in the room": you are selling rebreathers that you personally invite purchasers to modify in any way they please, to people who may have absolutely no training in diving rebreathers. I think that "kinda" puts safety issues in relation to WOB into perspective.

Simon, So you are telling me that there is no second hand market for rebreathers? Strange as I have seen quite a few folk in recent times buy an 1800quid Inspo of the inter web without any training!
If a customer does not have suitable training they seek it. There are plenty of eCCR divers that I have met that do not have suitable knowledge or training to dive a mCCR. Ever seen an eCCR not regularly check his PPO2? Ignore a cell warning? Ever seen an eCCR diver leave their O2 on, when they strip out of their kit! We do not quite yet live in a complete nanny state. For OSELs customers an advantage of their take on supplying functionally safe rebreathers is they can buy spares, as can homebuilders or even direct competitors of OSELs who want better parts (ALVBOVs included) than they can source elsewhere.

BTW as you well know, OSEL does not invite users to modify Apocs in any way. They offer them the choice to thread on a POD made by narked at 90 that takes off the shelf PPO2 monitoring electronics as fitted to other rebreathers. This has been tested to meet every single requirement of EN14143:2013. Users can certainly fit other harnesses if they want, if you call that a modification (certainly appears normal practise for other units) but if they modify the unit from how it was supplied in anyway, they know upfront that they will not be able to improve performance in any manner.

 

[cathal]

Simon, So you are telling me that there is no second hand market for rebreathers? Strange as I have seen quite a few folk in recent times buy an 1800quid Inspo of the inter web without any training! If a customer does not have suitable training they seek it. .

I think the point being made concerns NEW CCR's being sold by the manufacturer to members of the public who have no training on the unit. As opposed to every other manufacturer who usually either ship the CCR to your instructor or a vital component of the unit to your instructor.

Cathal

 

[Mark Chase]

Brad

Frankley its just bloody anoying your preaching about how good a BOV is that most of us cant use as it flows the wrong way

Its worse than anoying to go on about a ECCR unit it should be attached too that isnt actualy available to buy except in the mega expensive comercial twin scrubber version

Tool up, change the flow and start selling them

Yes I looked at the diagrahm and I dont see an issue as most of the componants are unaffected

Build the CCR and if its good you will sell loads. Just look at stuff like the JJ which went from nothing in 2010 to being the second most common CCR I see on dive boats

There simply is no need for the constant barrage of specifications and CE numbers and Id sugest its doing more harm than good

ATB

Mark

 

[Simon Mitchell]

Simon, quite happy with the difference between the two. What you are saying however, is ignore the recommendation you cited because it only works if your diving an Apoc (and potentially a Mk15.5 or rEvo if fitted with ALVBOV) so needs to be ignored!

I have never said "ignore" it Brad. Quite the opposite in fact. By not ignoring it I maintain realistic expectations of work performance at depth and plan dives accordingly (which includes use of assistive technology and planning of gas density). The biggest vulnerabity is the potential for a requirement for unexpected heavy work and if such a circumstance arose I could be at a potential disadvantage compared to being on a unit with much lower WOB. However, this too can be mitigated (eg by going onto open circuit for a period).

As NEDU provided testing for your unit, at 100m it is 2.99J/L on Heliox at 75lpm. So what is the maximum depth you can dive to on your unit, with OCB fitted, whilst staying within the cited recommendation? You get my point now.

Essentially answered above. The key is not to be ventilating at 75 L/min. Last weekend I spent 5 hours on a bike exercising at 6 Mets (agreed by expert consensus as a realistic sustainable workload during diving) breathing on a rebreather loop (as part of an experimental protocol we are currently running), and my ventilation was 35 L/min. This is less than half of the test figure you cite above. This is an example of why most diving situations are unlikely to take me into the zone where WOB is likely to cause me a problem, and because I am aware of the potential issues (that is, not "ignoring" them) I am able to mitigate the risk, or at the very least anticipate it.

What unit with low WOB suffers from poorer scrubber performance?

Potentially yours Brad. I have not been able to access the NEDU comparative evaluation because it is classified commercial in confidence, but the one thing I do know is that the US Navy has not adopted the use of EACs despite their convenience, and the USN would not be constrained by thier higher cost. It is possible I am misinterpreting these circumstances, but there it is.

Little hard to get a non-working eCCR CE certified!

That is a strange comment given how disparaging you are about the CE WOB standards met by other rebreather manufacturers. Moreover, didn't the iCCR get CE certified years ago? It is clearly still not working. And obviously if you could you would blow my argument out of the water by pointing to all the DL eCCRs in general use by happy customers, but you have not done that because there aren't any.

Simon, So you are telling me that there is no second hand market for rebreathers? Strange as I have seen quite a few folk in recent times buy an 1800quid Inspo of the inter web without any training!

This is a ludicrous argument. You are a manufacturer Brad. You are not selling second hand units. So all your talk about manufacturer responsibility only extends to work of breathing issues? Its OK to be completely irresponsible on matters as important as training?

If a customer does not have suitable training they seek it.

And you know this how?

We do not quite yet live in a complete nanny state.

Except in relation to work of breathing issues it would seem.

BTW as you well know, OSEL does not invite users to modify Apocs in any way.

Seriously??.... didn't you say:

You can also buy it with out elecs to do with whatever you want.

Brad, I want to reiterate that I do not disagree with all your points about WOB. It is an important physiological parameter which is best minimised. At the present point in time it is clear that many commercially available rebreathers may exceed recommended WOB maxima at different combinations of hard work, gas density and depth. This should not be ignored; indeed, it should be borne in mind by divers planning and executing deep dives. The current reality is that there are no viable alternatives for divers who have adapted to the configuation of equipment they currently dive, and who do not want to modify the basic oxygen loop you sell in order to make it work in the functional configuration they are accustomed to. As Mark has intimated above, the most productive thing you could do would be to shut up about other manufacturers and get on with providing a safe working viable alternative which will stand or fall on its own merits.

Simon M

 

[silentbob]

 

[Brad_Horn]

I think the point being made concerns NEW CCR's being sold by the manufacturer to members of the public who have no training on the unit. As opposed to every other manufacturer who usually either ship the CCR to your instructor or a vital component of the unit to your instructor.

Sorry I fail to see the differential risk regarding training or lack of, between new and secondhand units.
OSEL supply certified functionally safe rebreathers and are the only manufacturer to do so.
OSEL are not a training agency nor subject matter experts in the training of divers on rebreathers. They simply provide the highest performance kit available; ensure that any user is well informed of the risks they are taking.

Frankley its just bloody anoying your preaching about how good a BOV is that most of us cant use as it flows the wrong way

Mark,
Why folk are not asking manufacturers why they are not providing equivalent performance BOVs is an oddity to me.
Why folk buy or dive BOVs not knowing their performance, is just ludicrous to me. Simon has provided the criteria for both CC and OC WOB, that you should be demanding.

Its worse than anoying to go on about a ECCR unit it should be attached too that isnt actualy available to buy except in the mega expensive comercial twin scrubber version

Elecs from the Type II (the recreational version of the mega expensive commercial twin scrubber version) are interchangeable with the currently shipped Type IV Apoc.

Tool up, change the flow and start selling them

Mark, show me the market. As Simon says he dives a BOV with no idea of the WOB nor does this apparently concern him sufficiently to bother doing anything pro-active about it. If the "experts" are doing it, why would the bulk of the remainder, do any different?

Yes I looked at the diagrahm and I dont see an issue as most of the componants are unaffected

Unfortunately not the expensive bits. In the interim, you appear to just to have to make do with what ever L-R BOV manufacturers think is sufficient. Until "experts" like Simon start demanding better kit, me thinks you could be waiting a while. Or you could just buy a R-L flow unit like an rEvo and fit the ALVBOV to that, if you do not want the rest of the Apocs features: inclusive of the full loop flood recovery and lower WOB.

Build the CCR and if its good you will sell loads. Just look at stuff like the JJ which went from nothing in 2010 to being the second most common CCR I see on dive boats

Agreed. Point out a supplier of a solenoid fitted eCCR controller rated for use to 350m with EN61508 certification for recreational use and OSEL will be at the front of the queue.

There simply is no need for the constant barrage of specifications and CE numbers and Id sugest its doing more harm than good

It will only be seen as doing no good until other BOV manufacturers get off their tails and start to publish their own performance figures. Eventually someone will produce a BOV with identifiable comparative CC and OC to the ALVBOV in L-R flow and this is a good thing for divers.

In the interim, as I said to Simon, give me another comparative means of non-subjective BOV comparison other than hard benchmark able WOB data.

By not ignoring it I maintain realistic expectations of work performance at depth and plan dives accordingly (which includes use of assistive technology and planning of gas density). The biggest vulnerabity is the potential for a requirement for unexpected heavy work and if such a circumstance arose I could be at a potential disadvantage compared to being on a unit with much lower WOB. However, this too can be mitigated (eg by going onto open circuit for a period).

Okay Simon, you might not ignore it; you just do not know what it is.

You can only mitigate it Simon by going to an OC reg as your OCB could be (almost certainly is) part of the problem. When bailing out to the ALVBOV, Hollis BOV and probably Poseidon BOV - as all three have known low OC WOB ~1J/L at 50m/Air/62.5J/L - you are instantly mitigating the problem. What option is better?

The key is not to be ventilating at 75 L/min. Last weekend I spent 5 hours on a bike exercising at 6 Mets (agreed by expert consensus as a realistic sustainable workload during diving) breathing on a rebreather loop (as part of an experimental protocol we are currently running), and my ventilation was 35 L/min. This is less than half of the test figure you cite above. This is an example of why most diving situations are unlikely to take me into the zone where WOB is likely to cause me a problem, and because I am aware of the potential issues (that is, not "ignoring" them) I am able to mitigate the risk, or at the very least anticipate it.

35L/min is lower that the rate for scrubber duration tests agreed in every standard I aware of for overall mixed work/rest dives.

Plenty of NEDU/QinetiQ reporting that the 62.5L/min for OC and 75-90L/min for CC flow rates exist for very valid reasons and are easily achievable during routine diving.

When do you move your experimental protocol into a wet bell like they use in the serious diving trials that utilise exercise bikes?
And why are you reinventing the workrate for testing a rebreather using an exercise bike? I thought those protocols were quite well nailed down by the experts based on empirical evidence and a lot of in-water trial work.

I have not been able to access the NEDU comparative evaluation because it is classified commercial in confidence, but the one thing I do know is that the US Navy has not adopted the use of EACs despite their convenience, and the USN would not be constrained by thier higher cost. It is possible I am misinterpreting these circumstances, but there it is.

Simon, No possibility about it, it is certain you are misinterpreting these circumstances. Sometimes only having a little bit of information is dangerous.
As you have been advised numerous times before and could very easily check by discussing the matter with subject matter experts. To get the best out of an EAC from micropore, you have to design the rebreather around the EAC (as OSEL and Divex http://www.divexglobal.com/capabilities/commercial-diving/helmets-masks-and-scuba/show/cobra have done) and not try and jam an EAC into the rebreather (as APD, ISC, VR and KISS did).

That is a strange comment given how disparaging you are about the CE WOB standards met by other rebreather manufacturers.

In the majority of cases it is impossible for me to be disparaging as it is impossible for me to know the WOB in the first place. Please feel free to advise me of a 2nd BOV that you know the CC and OC WOB for.
AFAIK most rebreathers fitted with a BOV fail (unknown WOB counts as a fail in my book) to meet the CE WOB standards let alone come anywhere near close to your cited recommended levels.

And obviously if you could you would blow my argument out of the water by pointing to all the DL eCCRs in general use by happy customers, but you have not done that because there aren't any.

Sometimes hard to discuss things when your phishing and I am under NDA. AFAIK those customers that bought and paid for production specification eCCRs from DL were and continue to be happy with the rebreathers they received. The reasons for why they may or may not be in more general use is I understand it still being debated in court between at least one customer of DL and another party. Those reasons have nothing to do with the rebreather itself, as we discussed in person at Oztek.

matters as important as training?

Simon, your now a subject matter expert in rebreather training?

OSEL is not a training agency. OSEL mitigates the risk of supply of rebreathers direct to customers through supply of certified functionally safe rebreathers and notification of the risk to customers. Trainers provide training. A different protocol to what others use but when you take the real world actions of divers into account, not a demonstrateably unsafe one.

Brad, I want to reiterate that I do not disagree with all your points about WOB. It is an important physiological parameter which is best minimised. At the present point in time it is clear that many commercially available rebreathers may exceed recommended WOB maxima at different combinations of hard work, gas density and depth. This should not be ignored; indeed, it should be borne in mind by divers planning and executing deep dives. The current reality is that there are no viable alternatives for divers who have adapted to the configuation of equipment they currently dive.

Simon, So why is OSEL the only party who has addressed this problem for recreational users? Why are you not demanding better from manufacturers?
Why not start start with APD and have them provide you privately (thus no commercial risk to them) with the WOB of the BOV you dive. Why not point out the suggested recommended level that the WOB should be and have them provide you with a BOV that enables your rebreather to meet this.
Hell, have them buy an ALVBOV direct from OSEL and they can start learning how to reduce the WOB in their rebreather and their BOV. OSEL have knowingly sold more than a few ALVBOVs via proxies to a number of rebreather manufacturers.

and as you know it is not "may" exceed the recommended WOB maxima but rather a factor of how many times they currently exceed it by: for some units like yours even at 40m on Heliox and with a low work rate, you could be too deep.