Passive Scr Superiority?

steevke

Does anybody by any change has the figures split between the "classic" inspiration and the Vision (Inps/Evo), preferably split also over number of units in the field?

steven

decoweenie

... read carefully what units are grouped into mCCR, not just Jetsam units.

Can you explain this ?

How did these 3 companies come up with this number ?

Do they have number of other units in active use ?

We are playing number roulette here, and it is getting more interesting when numbers are pulled out of the a** (i.e. air )

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trob09

"There are three kinds of lies: lies, damned lies and statistics"

The first thing any researcher learns in statistical modeling is that correlation does not equate causality. There may be a higher incidence rate with one type/brand of rebreather over another, but this in no way can "prove" that one rebreather type or brand is more likely to cause a problem than another.

As several have mentioned, the low - and incomplete - data on various incidents do not allow for an adequate comparison from a statistics perspective - it is all anecdotal evidence and hearsay.

Additionally, many in this thread are approaching the problem with a conclusion in mind. Using only type and brand of rebreather for determining accident causality is a dangerously flawed approach to generating an actionable set of findings.

First, we must define all of the variables that can cause an incident. These will obviously include things like health, training, experience, dive frequency, level of difficulty, weather, gas selection, bail-out selection, self-rescue skills practice, equipment maintenance, adherence to protocols, buddy selection and location. It should also include lots of other variables that we don't typically think of when we are discussing accidents.

Once this data is collected (which it has not been) one can examine the relationships between various factors and weight them for their importance (i.e. likeliness to cause an accident) and influence (i.e. ability to trigger other accident factors).

Only then can we begin to assess causality of one type or brand over another. To use the meager data that we have to "prove" my unit is better /safer than yours is similar to stating that economic stability is driven by the length of women's skirts.

My suspicion is that if this work is ever done, brand and type of rebreather will be fairly low in importance and influence and that the largest drivers of accidents will be those related to the diver.

gtzavelas

For the point of this number game / exercise (if ever finally we will arrive to a point that will make sense) is it not safe to assume that the AVERAGE mCCR diver has similar traning / bail out / health / experience/ skills/ etc etc than the AVERAGE eCCR diver or the AVERAGE pSCR diver?

Is there any reason to believe that one type of user has more or less of one of these qualities? And its quite often that users jump from one type to another.

Personally I feel the bid difference in the numbers is NOT related to the above factors. (I think we all agree that there is a difference?)

And in fact although I dive a pSCR the “fact” that the percentage of accidents of mCCR "seem to be" 0% makes a HUGE point to me and has made me thinking that after all maybe mCCRs are “safer” than my pSCRs…

Dutchy

To me Boris seemed safest because I don't own one and I'll probably never own one...but then I thought well if I do buy one my wife will kill me. Does that mean it's not safe?

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trob09

Again, "lies, damned lies and statistics..." You are making huge assumptions with your average commentary. The simple fact is that there is nowhere near enough data to support what average is much less that any of these accidents fall within norms.

the point of my post is that you are looking for data that supports your conclusion. If it makes you feel better, fine. But don't expect it to prove anything.

Marc T

A good way to choose a Rebreather or not could be which one for your wife and why

Dutchy

Interesting serious comment to a joke. I guess if you are still in love you might opt for a rebreather with features that presumably add to safety rather than whistles and bells that improve the gadget factor.... I you don't well I won't go there .

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AD_ward9

I agree with you on KISS. In my first post on the Know Your PPO2 thread, I said the Draeger SCRs had the best safety recorded, followed by the KISS. I just don't have numbers on how many KISS type units there are out there, of the different breeds of KISS, so did not want to try and come up with a figure for the KISS. My gut feel is that there are some hundreds of KISS units in use, so the accident rate is well under 0.3%.
There was one fatality with someone using a KISS. I do not have the circumstances to hand.
Interesting the different means. The figures all seem to point the same number, whether based on the amount of lime APD sell each year, the number of O2 sensors Teledyne sell them each year and R22Ds generally, the number of silicone mushroom valves APD buy each year from P****, the number of Inspos in dive clubs or Inspo cylinders returned for service. Statements Martin Parker has made to vendors who supply us and other OEMs. Build quantities people report seeing in factory tours. Have enough data, and the fuzz fades out of the picture. Interesting well known 3 companies providing components or services in the dive industry each arrived at the same number themselves, give or take 50 units. Outside the UK it is much more patchy. We know exact numbers from some manufacturers, but have got that in circumstances where those giving us the information do so confidentially.
Which is why in accident reviews we do go to some lengths to get decent numbers.

It is important to do sanity checks. Just think, BSAC have about 50k members. Many are inactive. How many use a rebreather? Just turn up at BSAC event and see. Not a lot. A few percent. So there is unlikely to be 5000 active Inspo users. I pick the UK, because Inspo users seem to have the highest density in the UK.

Go into a dive shop in a busy area, and how many Inspo cylinders or regulators are there for service? Speak to the technicans and how many have they serviced in the last year. One of the three companies I mentioned supply gas equipment to these dive outlets, so see a lot more dive shops than I do.

Can RBW publish how many users it has, for each type of rebreather? We can then do a poll and find out what propertion of rebreather users are on RBW, by contacting one of the dive training agencies to see how many XYZ agency rebreather divers are here, compared to how many have cert cards. That would be a useful thing to do. Given the population size is large, this would give a fairly precise confirmation of numbers. Is RBW able to do this, or is this Data Mining and prohibited?

The list of rebreather faults has been prepared: have a look at the Know Your PPO2 thread. Accidents are analysed with the rebreather fault list published there. We do know roughly how different rebreathers come up on that fault list, and it does correlate reasonably with their accident rate.

A good example is the Inspo, as it had a very high accident rate until improvements were made. Per user, accident rates fell after 2000. Training was much the same. Just handsets after that date have a watchdog timer so do not just hang, at least not very often.

The aircraft industry grew out of the "blame it on pilot error" mindset in the early 90s, and aircraft became a lot safer as a result. Time now for rebreather equipment.

Cheers

Alex

steevke

Not always meaningful info: eg I don't use inspiration mushroom valves as I have a BOV on my unit that uses other valves - and a lot of people do. I use Spherasorb instead of Sofnolime. Some people use their sorb for 4 to 6 hours, meaning that more dive time is logged than you can calculate out of the sorb quantities sold. Some people won't send cylinders or regs to a dive shop and do maintenance themselves. If cylinders needs testing you can bring them yourself to the hydrostation. If they need cleaning I clean them myself. I don't know how many people have their inspiration serviced by APD but I don't think all of them do...

I do agree that on the Classic Inspiration the number of units in the field is (way?) overstated: some people I know have 2 or 3 classics in their garage, usually 'teaching' units; others changed the Classic head to a Hammerhead, others took the Vision update.

I would really like to see actual figures of incidents versus rebreather makes/types. Unfortunately about the only number we can be certain of are the casualties - damn too much.

steven