[iain-hsm]

Without prejudice.
For some time now I have been thinking about the questions of testing within the recreational rebreather market. Most of our arguments (OK maybe mine) have been due to a lack of published transparent data.

I don’t think anyone argues with the current published results. The CE testing of the Inspiration and Oroborous or with the published US Navy testing of the Prism. But if we include all the other major players MEG Kiss, O2ptima and then add to the mix some oldies Cis, Draeger, MK 15/5. You see what I am driving at.

Truth is maybe some home build or unknown or obsolete rebreather hiding under a blanket of obscurity is the best out of the lot I have listed. You don’t know. We don’t yet know.

It’s all very well for some manufacturers to hide the actual performance under the blanket CE certification or some self congratulatory attributes of another brand but this puts a huge gap our purchase perception. Further our purchase decisions are further complicated by “stunt dives” with subjective testing and no replies to questions.

I hope no one takes offence here (with my posts there a good chance someone will) but take the CIS Lunar MK5 (now obsolete). Even with all the super dives it has under its belt there has not been one single subjective test result on the product…Ever. (apart from the US Navy test report) yet its “claims” appear to be greater than its performance.

At present we are hard pushed to be able to draw anything but a rudimentary correlation between each claimed test let alone against different brands.
But we may be on to a good thing here. No one has yet done it so I propose to have the RBW players, do it for ourselves. (or is that some sort of lesbian thing?)

This is something that has been “promised” for some time, the same test between the different brands using the same test conditions. However the cost in manpower time against is prohibitive. So RBW we make some simple cheap tests.

I have been involved in a private capacity with our miniature C02 detector to see what it is like with everyone else’s rebreather our cheap modification was to make an adaptor and bolt the thing into the inhale breathing tube. It was the easiest and cheapest solution. It worked under the wire of these costly directives.

What I would like to see is a test self help group being formed within RBW to draw up the cheapest test protocol we can where we can both EU and USA test each of our units, compare and publish the results. DEMA 06 is in November I submit this would be as good a time as any for a get together

I am not looking for a EDU or ANSTI test here just the rudimentary test procedures set up so each rebreather can be tested on a cheap budget say like the regulator test WOB using a cheap magnehelic gauge purge flow on a flow meter.

What I propose is something like:
An agreed cheap test bed design for surface testing
A test bed bill of materials, so all the testing kit parts are the same
A model for the test procedure, so we all test to the same perameter
A test procedure.
A crossover or calibration of test equipment, so each test is traceable.
An underwater shallow water trial (bungee cord and a hard swim against it)
An agreement that we publish in RBW the results.

The primary goals would be canister duration test. The second a WOB test.
I would be most interested in anything you guys think we should do?

There have been a number of interesting posts not so long ago on V02 peak performance self testing. That an exercise bike, stop watch and breather is one possible way. A C02 bottle regulator and 1.6l/min flow meter with breathing machine is another. A C02 detector would be required not expensive if we look at some of the detectors used in pubs or beer cellar C02 detectors, quite adequate for this. Anyone interested, any thoughts.
Iain Middlebrook iain@hsm-engineering.demon.co.uk

[Mark Chase]

Quote:

The primary goals would be canister duration test. The second a WOB test. I would be most interested in anything you guys think we should do?

I would like to see a lot more information on the controlers and independent bench testing of falt paths. Too many odd ocurances of glitches in hand sets.

Scrubber duration isnt realy a major issue as we all know the 40rmv 5c test is prety harsh. WOB doesent apear to be much of an issue unles you think it has serious c02 implications?

ATB

Mark Chase

[Mdemon]

I think the aim is a good one; we will be able to compare apples with apples, not the current apples with oranges, bananas etc.

The objectives have to be simple and cheap to achieve. Yes, it would be great to see how closely a PO2 is held but it would be really difficult to do. So scrubber duration and WOB seem the easiest things to measure.

How will you take into account temperature and depth?

You really need a weekend at the AP factory using their test gear. Maybe that's a total fantasy, but wouldn't it be good to test all the major units using the best testing equipment available to us?

[Ben Field]

Quote: (Originally Posted by Mdemon)

IYou really need a weekend at the AP factory using their test gear. Maybe that's a total fantasy, but wouldn't it be good to test all the major units using the best testing equipment available to us?

I'd wager my salary that AP have had far more rebreathers in their test equipment than the two they make.... of course without the other manufacturers approval we'll never see the results as it could be argued the tests would be baised towards APD.

RBW probably has as much knowledge and ability to come up with a realistic side by side test as any other "body" out there... plus we are the only group likely to want the information, I suspect alot of manufacturers fear this kind of full discolsure you are look to achieve.

BEN

[jradomski]

IAN, you can count me in on whatever testing youd like to do.. I have access to or own..

Inpiration, Sport KISS, Meg (standard scrubber and CIS scrubber), UT-240, (UT-180 or UT-90 not sure which one), Can probably get access to a CIS.. Infinito (ccr), maybe even a Gator..

There are a few PRISM owners that are close to me so maybe one of those guys could join in as well..

[paulraymaekers]

IAN, if you want to test a rEvo, just send me a mail!

regards
paul

[RichClark]

Quote: (Originally Posted by Mdemon)

I think the aim is a good one; we will be able to compare apples with apples, not the current apples with oranges, bananas etc.

The objectives have to be simple and cheap to achieve. Yes, it would be great to see how closely a PO2 is held but it would be really difficult to do. So scrubber duration and WOB seem the easiest things to measure.

Totally agree, although these tests may not be a sophisticated as APD's they would still be valid and aid direct comparison between units. I'd actually be surprised if most major manufactures haven't had other units on their test bed for comparison purposes.

I'm not sure exactly how I could help, but I'm happy for you to use my Classic KISS.

Cheers

Rich

[EBT]

Iain,

It sounds like you're talking of a multi stage process;

1. Agree testing regime/method
2. Agree reasonable rig
3. Create test rig
4. test units and share results

Given that 1 & 2 'should' be relatively simple (how many times have you heard this!?), when it comes to 3&4, are you suggesting that HSM/yourself would do this? I guess the issue of cost would appear at some point, but you're trying to pool brainpower to create 1&2 first?

As for unit availability, Im sure we'd all offer our units FOC, so perhaps we can avoid cluttering thread with those sort of replies


/Zak

[onetime]

Sounds like an excellent idea. Once the details are figured out I'll gladly help if you need access to a Classic KISS.

--Paul

[Duncan Price]

Quote: (Originally Posted by iain-hsm)

There have been a number of interesting posts not so long ago on V02 peak performance self testing. That an exercise bike, stop watch and breather is one possible way. A C02 bottle regulator and 1.6l/min flow meter with breathing machine is another. A C02 detector would be required not expensive if we look at some of the detectors used in pubs or beer cellar C02 detectors, quite adequate for this. Anyone interested, any thoughts.
Iain Middlebrook iain@hsm-engineering.demon.co.uk

Iain

I would be interested - I'm sure you will have no problem in sourcing units.

For a simple test I would consider passing (say) 25 l/min of (say) 4% CO2 * in air through a thermostated (just place it in a bin of water at ~10°C) scrubber. Measure the gas pressure differential, air temperature differential and CO2 outlet concentration with time.

Gas pressure differential will give an idea of the WOB (just of the scrubber).
Temperature differential will give an idea of whether calorimetric monitoring is any use.
CO2 to detect breakthrough.
Test protocol could include using different sorbents as well as scrubber units.

I recognise that this is a very limited test (at 1 atm) but should be easily achievable in the field and certain should provide one datum point in the "my scrubber is better than your scrubber" debate.

* or some other arrangement - say a CO2 bottle flow meters and air line.