Input on Sling rebreather design.

PoseidonSv

I am planning a slidesling rebreather using plastic pipr as container with Ray scrubber and ray Dsv. The counterlungs will be on the top as will the overpressure valve.

Will I have a need for a ADV if i run it manually?

I think i will add a nozzle that will deliver 0.7l/min when o2 bottle is turned on
And i think i will use the bottom P-port on the scrubber for this

Since it is a bailout unit i will insulate the scrubber with neoprene to keep it warmer.

Maybe i can find small bottles for O2 and Dil that will fit inside the pipr itself or maybe one bottle inside and the other strapped to the outside.

I would like it to be completely independant unit that can be donated to buddy during the dive if desired so independant supply of dil and O2 might be the way to go.

I guess i will need to add some lead to the top of the unit to make it neutral boyant in the water also.

DepthCharge

I would think that an ADV would be advisable (IMHO). Keep the thing from being crushed. Leave the dilutant on and the ADV will keep it at ambient. Also in an emergency it will give that first breath instantly.

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Later,
John

It's better to beg forgiveness than ask permission

Outlaw

i have been thinking about something like this for a while now, but unfortunately did not manage to overcome one main concern of mine on the issue.

suppose you have your sling rebreather, and you are diving away on your main one, how are you going to regulate the setpoint on the bail out Rebreather, so it will be ready when you actually need to bail out, to go on a "good bail out air"?

again, suppose you somehow manage to keep that, then the scrubber wont have air circulating so it will initiate the reaction from the scrubber...

that is the dangarous part i guess. i did not ask advice from others on this, but this is due to lack of time to focus on something so demanding.

hope you have thought of these.

Thanks for reading.

Spyros

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wedivebc

The entire loop will be filled with a diluent that can be breathed at any depth of the dive plan and the O2 only gets turned on when it is being breathed from.

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Dave....

Man is the only animal burdened with the knowledge he will eventually die

DepthCharge

Exactly, you need to plan your dilutant for a PO2 somewhere in the neighborhood of 1.3 for your target depth.
Also there is a good bit of discussion about going onto a "cold" scrubber. Not sure that there is any real hardcore data, but several have posted that they have not had an issue with it. YMMV

__________________
Later,
John

It's better to beg forgiveness than ask permission

Outlaw

hmm...sounds logical, but i thought that there must be a constant flow of the loop to keep the reaction of the scrubber going. isn't this the case?

Thanks

Spyros

__________________
CMAS - IANTD - TDI
Kamikazi Instrustor Trainer
DIRRebreather Team Member
----------------------------
"Once an Outlaw, always an Outlaw"

dz3866

I am working on a sidemount design with the scrubber inside the lung, I think with this design, it makes the unit a little more compact, and breathing on the unit a good 10mins before diving will keep the loop at a good temp and in good shape for bailout. Will post pics soon.

jaap

Hi Fredrik!

I would say there is no chance that you will manage to fit bottles inside the pipe (unless you get a silly big pipe). If you want is completely independant with its own cylinders I guess you would have to think hard about the minimum size of them. These would probably fit nicely on the outside: http://www.tecme.de/bilder/tank_07SS.jpg
from this page:
Used Rebreather parts and more

But 0.7l 300bar would not be much gas. To little for my taste.

I we are talking about the ~144 mm ID pipe you found, space will really be an issue. I'm thinking the pipe will have to be quite long to hold enough volume for a minimum loop volume.

If you are not going to breath from it during descent an ADV would definately be good. Crushing the loop severly increases the risk of a flood. Switching to a loop with negative pressure can be quite risky too...

Do you really need a bailout Rebreather or is it just for the fun of it?

Anyway if you don't breath from the unit while diving remember to turn the O2-flow off. Otherwise you might have a really nasty pO2 in it if you switch to it at some depth. If an ADV is connected it will keep the loop at dil pO2 so with a sensible dil you have time to turn the O2 on after switching to the unit.

Lets hope we can get around to check out our homebuilds and do some diving this fall!

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johnv

You will likely need more lead than you think, but trimming the unit is the last thing you need to worry about.

If you go semi closed when you switch for a few minutes, you should not have any problems with a cold scrubber, however bear in mind the ray scrubber is pretty small and designed for semi closed in the first place, therefore it's depth limit won't be great.

if you don't have a ball valve or disconnect on the ambient side of your KISS valve, the valve will flood at depth. This isn't a problem as when you begin to use it you blast the water into the CCR (it shouldn't be much) but you hve to dry the inside of the valve after each dive.

have fun
John

wedivebc

Although I can't provide any hard data on that, I have been told the chemical reaction starts almost instantaniously by someone I trust would know this information.

__________________
Cheers,

Dave....

Man is the only animal burdened with the knowledge he will eventually die