Open source rebreathers - an alternative approach

uri

I fully agree. I see this as an attempt to bring together the knowledge and skills of homebuilders to enable people to take aspects of 'proven' designs and use them with other components and designs. At present as you say, there are open source designs out there but if you follow them you get exactly what the original designer built. By pooling knowledge, no one needs to re-invent wheels. Surely a guide to what's out there and what's compatible with what would massively ease the problem of 'getting the bits together in a cost/time effective way'?

If someone needs a counterlung and has a choice of 3 compatible types and 2 DIY designs, that's good isn't it especially if they are cost conscious and want to focus their design and build skills on only a specific part of the Rebreather.

Rgds

U.

onetime

Hey Duncan,

I think you are absolutely right, open source is already out there in some regards. What I, and the others here I think, envision is a concerted cooperative effort that may lead to a process that isn't just a one-off production of a homebuild.

No doubt we will leverage what's already out there but I also don't doubt that there are some great ideas in the minds of all of us that can bring about some interesting inventions. Sharing skills as Genesis proposes might help to transform some of those ideas that are on paper in a hundred different notebooks into reality.

--Paul

Genesis

The MSR waterbags are definitely workable for counterlungs. They've even got convenient attachment points for hold-downs if used OTS, although they're a bit fat (rather than long and skinny) for that service. It'll work but may not be ideal. For BM they'll be fine and in fact are what the KISS Classic uses. Modifying the caps to retain an O-ringed pipe is not difficult. If you want you can actually buy the O2ptima counterlung system from DRE (the whole shooting match is about $500), but the T-pieces required to make it truly servicable aren't part of what's available online (grrrrr.)

The big deal is likely the scrubber. I'm not aware of any off-the-shelf systems available at a rational price ($1k is not rational guys), and the "second hand" ones you see pop up that were originally for a Ray or Azi sound interesting until you think about wanting a "head" - then it becomes maddening instead of interesting. What's needed here is a scrubber with enough room in the top for you to mount "whatever", whether that just be 4 cells (3 + your computer's), that plus a solenoid + small driver arrangement (just interconnects, or a small driver board), etc.

The other small bits (e.g. cylinder mounting, etc) are easy. If you use a plate + STA as a mounting base, you've got the buoyancy/harness system.

Hoses can be somewhat of a PITA, but that problem is solvable, as there are commercial ones out there - you just have to find someone who will sell them to you. You can get the O2ptima ones online, for example.

If we had a T-piece and scrubber solution the mCCR is a piece of cake. An eCCR then becomes a matter of the electronics.

I suggest that the focus of this, as a consequence, really needs to be on the scrubber and T-Pieces for OTS lungs. Solve that and "the world's your oyster".

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"A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American."
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Duncan Price

...or four-off production of a homebuild and sell three of them....(not that I made any money on it). There are various other "homebuilds" that have had sizeable production runs...

I'm not sure of the purpose of this though. One could envision a group of homebuilders designing a unit together and producing a kit from a mixture of commercially available and bespoke components. Or perhaps there just needs to be a central resource of ideas and places to obtain parts with various recipies to put them together.

Ben Field

Neither the Prizm, KISS, Mk15/16 series, Draeger or Rebreather-80 use T-pieces, they all have different, imaginative ways round it, not all of them easily replicated but the T-piece is not the holy grail.

I think perhaps the difficulty you see is from your perspective, I take it you are good at electronics? I'm not, I wouldn't have a clue where to start, but I could biuld a T-piece before, well... tea :-)

FWIW I saw a homebuild recently with a kind of t-piece that used two 90 degree pipe elbows back to back, they both plugged into the CL's through the same round fitting, the designer had softened the elbow where it entered the fitting so it was oval (and would hence fit) I was simply elegant and apparently effective.... will see if I can find a picture.

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Duncan Price

Ben has hit the nail on the head - I'm good at plumbing and therefore it shows in my rebreather. I got my (passive) electronics from someone else...

And because of the sort of diving I do, I'm not interested in a back mounted rebreather - otherwise I'd have bought one.

onetime

I agree, it doesn't necessarily have to be a t-piece. If one were to make their own counterlungs, they could easily add a second connection to circumvent the t-piece. Think of the MSR water bottle with a neck on either side. Front side would attach to hose, back side to the scrubber.

Genesis

Hmmm....

__________________
"A venturesome minority will always be eager to get off on their own, and no obstacles should be placed in their path; let them take risks for Godsake, let them get lost, sunburnt, stranded, drowned, eaten by bears, buried alive under avalanches - that is the right and privilege of any free American."
http://www.denninger.net
http://www.diversunion.org/liability.htm - Fix the Diving Cert racket

Crazyduck

I agree on the MSR waterbag.


In the front and out the back you could use a bulkhead coupling to make the back watertight.
Also pond parts sellers have some interesting things. CHEAP...

Bulkheads http://www.aquaticeco.com/index.cfm/...ories/ssid/327

Andrew

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Rob Davie April 2005-

Presently in a state of transition from Open Circuit to Closed Circuit.

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onetime

For a real nice fit/finish, you could also just buy 4 4-liter water bags (assuming you want two counterlungs), separate the fronts and backs and rebond the fronts to each other. Of course you'd need someone to do some ultrasonic welding on them but it would be a real nice finished product.