That is the best way to purchase a ticket to heaven!
Check the numbers for yourself and take nothing on face value when it comes to rebreathers (buying a tooth-brush is another story).
That is why I place so much emphasis on actual numbers... it is the actual performance figures which make the difference between a Yamaha FZR 1000 and a Piaggio Vespa or a Ferrari and a Fiat (all are "CE" but one is very different from another).
Current Radials are by far superior to current Axials and safer, based on available data.
A new member to this forum asked for some advice regarding a rebreather purchasing decision, which I endeavored to constructively respond with information that I felt would be understood by someone new to rebreathers. I therefore find it disappointing that you should selectively edit my advice and intimate that if my advice is followed, it will result in the enquirers demise.
With regards to CE marking, I felt I included sufficient caveats to clearly make the point that CE provides no absolute guarantees. However, in the absence of any other formal civilian rebreather test standard, it does provide assurance that the rebreather has met a minimum performance standard. In particular, the original query concerned canisters used in cold water. From memory (I'll need to confirm), CE harmonised standard EN14143 un-manned canister testing is conducted in water at 4°C at a CO2 injection rate of 1.6 l/min, at a breathing rate of 40RMV (2 lt tidal volume) using humidified gas at body temperature. Therefore, regardless of axial or radial, the canister, or more to the point, the whole breathing loop because the management of water can play a significant role on canister duration and gas flow resistance, has been tested in cold water typical of the environment in which the original enquirer intends to dive. In contrast, your response to my post was to suggest that CE testing of underwater life support is of little or no value based upon unrelated examples of medical implants. As I mentioned, CE marking offers no guarantees, however if a rebreather has been subject to CE testing, the enquirer will know, with confidence, the cold water maximum canister duration based upon empirical testing regardless of what type of canister type it is. Empirical canister duration test data is safety critical information that needs to be understood and complied with when diving in cold water.
Your effort to collate rebreather performance test data is a worthy endeavor. To use your words "that is why I place so much emphasis on actual numbers..." but as you correctly pointed out in another post on this subject "reports/numbers can be confusing at times" and never more so than when it comes to trying to make sense of different canister performance data. As a rebreather novice, what chance has someone new the technology have in interpreting such data? Very little I suggest. This is why I felt that in terms of practical constructive advice, despite the nuances between axial and radial designs, recommending the purchase of a rebreather that has been subjected to cold water testing was far more important than the canister type.
Let's consider someone who based upon your intimation that CE testing of underwater life support is of little or no importance because to use your phrase, "it is the best way to purchase a ticket to heaven", this person who lives and dives in an arctic environment purchases a non CE marked rebreather that has not been subjected to cold water empirical testing. Who now is at greater potential risk when diving in 4°C, a diver with no cold water canister duration test data and so subjectively makes up the canister duration or a diver with a CE marked rebreather who complies with the manufacturers cold water canister duration recommendations? Again to use your words "that is why I place so much emphasis on actual numbers..", CE testing provides those numbers and therefore I would have thought fulfills your self declared emphasis upon the importance of such numbers, which can only be derived from empirical testing. EN14143 is the only international civilian rebreather standard that provides such data. I therefore struggle with the apparent contradiction regarding your emphasis on numbers to make an informed decision and your post regarding CE harmonised rebreather standard EN14143, which again to make the point, is presently the only civilian international rebreather standard that provides the data you seek!
Debating the so called "safety" merits of one canister type over another offers the enquirer in my opinion nothing of meaningful practical value; define "safe" and just as importantly define "unsafe". I've spent long enough in rebreather development and in the lab witnessing canister duration runs over the last 15 years to come to appreciate that to consider one canister design type to be "safer" compared to another canister design type is in practical terms a meaningless academic debate unless the breathing loop in which the canisters are embedded and the test conditions are precisely controlled and standardised, which is often not the case when making generalised comparisons with what is on the market. Even if it were so, to then define one as "safer" compared to another is quite meaningless in my opinion because "safe" and "unsafe" have no clear definition. Safe is not a black and white line. One canister may perform better than another under certain test conditions; this does not necessarily correlate with one being "safer" compared to another, particularly because the conditions of "real world" use are infinitely variable. What is of tangible meaning to someone starting from a potentially low rebreather knowledge base is that a rebreather has been independently tested in accordance with an internationally agreed standard and so meets a minimum agreed performance criteria and that there is clear manufacturers maximum canister duration guidance based upon empirical cold water testing, which reflects the enquirers intended condition of use.
As I stated in my original post, "in no way do I propose that this standard represents the pinnacle in rebreather standards nor does it guarantee you will get a great performing rebreather". However to ensure our safety, society accepts and expects safety related legislation to govern consumer products and services, e.g. domestic electrical appliances, medicines, food, water, restaurant kitchen cleanliness, civil construction etc. Surely then is it reasonable that the same level of consumer protection is applied to rebreathers, which after all are underwater life support equipment. Indeed it can be argued that failing to impose a minimum standard is a dereliction of duty by national / international bodies charged with the responsibility of protecting the public from poorly designed and manufactured product.
With the many complex engineering issues associated with underwater life support systems, as an initial effort at defining minimum standards for rebreathers sold within Europe, it was inevitable that certain aspects of EN14143 would be subject to review and future amendment. This said, the European rebreather standard has set the international benchmark against which manufacturers globally are now measured. As a consequence the standard of sport rebreather design, production quality control and performance has been raised and this has and will continue to make a contribution to rebreather diving safety.
To conclude then, we as seasoned rebreather divers who engage publically on the web have a responsibility to provide safe considered advice to those new to rebreather diving regardless of our personal opinions and so I will leave the forum membership and the original enquirer to decide who has tried to offer such advice in this instance.
Rgds Paul
) to say that "is has shown not work very well" is a bit ridiculous.