ISC posts test data

jradomski

unfortunately mike you can not compare duration numbers.. navy tests are done at 50fsw instead of 40m and they use a lower co2 addition rate at times. They test using rest/work cycles.. (rest cycles of .9lpm and work cycles or 1.6lpm co2). There is no mention (that I can find) of the actual ventillation rate during the co2 endurance tests..

Endurance at 50fsw is going to be significantly higher than 40msw

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Joe Radomski
CCR Trimix Instructor Trainer
ANDI Instructor Trainer Director #10

All posts are personal opinions and DO NOT reflect any affiliated agency unless specifically stated.

Drmike

yeh i just realised that and pulled the scrubber duration graph - then read your post

anyone know what meg/inspo do at 50fsw? for comparison

wob results are valid as they use same parameters

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Cave diving is a sport
Wreck diving is a sport
Diving in general is a sport

'Rebreather diving' is not a sport
its the delusional obsession with a highly dangerous and often inappropriate piece of equipment

AD_ward9

The Meg has a higher WOB than the Meg mouthpiece. I may post the figures ahead of the Boris, if we can get a Boris.

Even more a dagger through some of the young pretenders that have tried to claim the throne since then...

And, to answer Mike Gadd, if you send in a Mk15.5 with Rexnord mouthpiece and Mk16 hoses and Mk16 centre section, then we will test it and publish results under the exact EN14143 conditions. Note the 1.97J/L unit is by no means a standard Mk15. The standard Mk15 looks pretty abysmal in comparison.

The Mk15 and Mk15.5 results in the report you kindly linked, is a very good example of what happens when people doing development actually have the test equipment to test what they design: the result is a much better product very quickly. It also illustrates the poor performance on units that are not tested (the straight Mk15). Supports the 2nd Rule of Engineering: if it has not been tested, it means it does not work.

Alex

Hanssing

OK, I can't figure out how that can be.... The areal inside the hysteresis of the curves (lisaju?) represents the work, and if this work is lost to say turbulence then it is lost, no?
I simply cannont see how a design could produce lower WOB.
Anything short of breathing-assistance and I'm confused
Perhaps something wich makes the flow laminar when put together with the mouthpiece, but turbulent without, but then its part og the mouthpiece?
Edit: I'm bonkers, I know... But there's energy beeing released in the scrubber, somehow using this?

I have no dobt that there's an a good explanation, so I'm intrigued.

Unless its a trade/patent issue would you care to tell how your statement above can hold true?


Nicolai

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Woohooo - I can change my rEvo!
Its going to be bitchin' tricked out piece of gear

Drmike

Thats the MK15.5 WOB figure (basically from a loop perspective, a mk16) apples and oranges

yes if by standard you mean with the original small bore hoses and dsv. But few people are still using the original dsv Im sure.

just using a larger mouthpiece and hoses enables the 30+ year old mk15 design to achieve 2.29 J/L (better than Meg/Inspo etc etc)

__________________
Cave diving is a sport
Wreck diving is a sport
Diving in general is a sport

'Rebreather diving' is not a sport
its the delusional obsession with a highly dangerous and often inappropriate piece of equipment

AD_ward9

There is a trick. All will apparent in the WOB verses Loop volume curves being published alongside the normal pressure tidal volume/resistance Lissajous.

It uses the fact that the lissajou is not symmetric: exhale resistance is larger than inhale normally, so a very small amount of positive pressure can balance the curve. It is only useful if the mushrooms in the mouthpiece are both large and very floppy, hence the Boris and O.R. units.

Alex

AD_ward9

Some BOVs do go the other way ... but yes, if you upgrade a Mk15 by replacing the mouthpiece, hoses and centre scrubber section, you can get some very respectable figures. However, unless someone has tested their exact configuration, how do they know where they stand in the space between "abysmal" and "very respectable"? 2nd Law of Engineering comes up again.

Alex

Drmike

Sorry to be pedantic Alex , but according to the report the standard mk15 achieves 2.29j/l with just a change of hoses (to MK16 ones)and dsv (to Rexnord one) - ie no center section change, 2.29 is certainly respectable. Of course swap out the center section and its even better

I think every mk15 ive ever seen, was long ago upgraded to rexnord dsv and hoses (same as test report) so perhaps we should look upon thjis as the 'standard MK15'

yup - it never stops amazing me (and i made this poit before) how people buy units without asking to see wob and scrubber results. the colour apears to be very important though

__________________
Cave diving is a sport
Wreck diving is a sport
Diving in general is a sport

'Rebreather diving' is not a sport
its the delusional obsession with a highly dangerous and often inappropriate piece of equipment

AD_ward9

OK. Send me it and I will test it to confirm.

The reference to the centre section is on the page that starts with "Block No. 20 Continued", .. the Mk 16 scrubber was fitted. It may or may not have an effect on WOB.

I agree with you completely on your point on the colour. Until 2nd Law of Engineering kills them.

Alex

silent running

Some of you may be surprised by my posting this, but just to make sure the Prism is represented in this discussion:

Prism achieved 1.696 J/L @ 75 lpm @ 150ft=45.72m resistive load as tested by NEDU.

I assume that this is a total loop WOB figure, not just the mouth pc and that the mouth pc/DSV could not somehow be higher in this case than the overall loop WOB.

Am I correct?

Alex?

Anyone?