oxygen ccr conversions

OceanOpportunity

Hello all,

I'm looking for specific feedback from those who have converted the C96 to mixed-gas. Most have said WOB is too high at depth, however there has been some discrepency here. I have already viewed the easy to find websites on this (Pawel, Volanthen, etc), but want end-user feedback on the vlaue of assembling such a system.

Also, anyone have info on the Poseidon Oxylon? availability? price point?

many thanks

Dave Sutton

C-96 pro works great. Old C-96 was scrubber limited to about 130 feet or so... I "think" I was the first one to do a mixed gas conversion and it has worked fine. I know that it inspired others to do the same.

LAR-V makes an excellent mixed gas rig as it has a superior scrubber.

The big picture on all 02 rebreathers *with an ADV* is to fill the old 02 bottle with diluent so it feeds the ADV and then add a new 02 feed system of your choice, either manual or KISS or ECCR as you see fit.



The big picture on all 02 rebreathers *without an ADV* is to EITHER:

(A): use the original 02 bottle and feed for 02 and to add a new diluent feed system (obviously this limits the system to a manual add system only)

OR!

(B): Use the old 02 system as diluent and make a new 02 feed system. I use this method as it allows me to make a KISS 02 system as a plug-in.


Since you are in Providence and I am in Narragansett, why not come down one day and see for yourself how I do it? There is also some information on my website here:

Diver Dave's Minimum/Bailout Rebreather




Dave

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"Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com

OceanOpportunity

thanks Dave, I've viewed your web pages on this, and they were helpful.

Can you comment on what has been changed on the 'new' C96 scrubber which has improved its depth capability? Also, more generally, I cannot find a good schematic on gas flow path through the C96. Do you exhale first through the bag (making a water trap), or through the scrubber, in which case the bag is an inhalation bag? I would suspect that these influence position of O2 sensors, etc

thanks for your input
ML

OceanOpportunity

Dave,

would LOVE to visit in narragansett and check out your shop...you can contact me privately at explore@oceanopportunity.com to pass along directions, good mtg times..I am very flexible

Mike

Dave Sutton

The gas flow is the same for both the old one and the pro, just the scrubber size is different. The system is a simple one, exhale thru the scrubber, into the bag, and inhale outta the bag. The bag is a perfect place for sensors, using a P-Connector and one of my PP02 probes. I use the probe also as a gas injection point now. I'll show and tell when if you come diving with us one day. Water traps are an ingenious solution to a non-existant problem... if you flood the loop it's not a rebreather any longer.... so forget water traps and keep the DSV in your mouth... if water traps were a desirable requirement, the Mark-15 would have one......

I don't run a shop there, I run a dive boat (probably the only one that *encourages* the use of experimental rebreathers). Narragansett Pier Dive is the local rebreather friendly dive shop and I do hang out there a lot.


Dave

__________________
"Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com

OceanOpportunity

Dave,

thanks for the continued info. As for gas injection into the bag, what are your philosophies on injecting both O2 and dil into the bag (being on the inhalation side of the scrubber), versus injecting at least the O2 on the exhalation side, theoretically allowing for a more thorough mix through the scrubber.

Are you free next week (after turkey day)? I'll buy lunch

Gibbon

Are you saying that it is some other demonic influence that runs the "Shop of Horrors" ?

I have struggled & failed to get a C96 in Malaysia, the supplier is a complete waste of space

I will be trying again in europe I suspect in January.

Phi on here (RBW) tested a C96 to around 70m but only for a couple of dives, he still has the unit but is not keen to sell it as he likes it so much.

Dave Sutton

The Little Diveshop of Horrors is in New Jersey, it's my garage / machine shop where the infamous rebreather slab is located. That's about 220 miles south of the boat. Summer Quarters are aboard EXPLORER, Winter Quarters are at the house. EXPLORER just came out of the water yesterday (sad day....) so the LDSOH is in full swing until April 15th when EXPLORER becomes home again.

Injecting 02 and dil into the C-96 bag? Just do it. The gas mixes so quickly it's virtually instant. I think that most people over intellectualize this stuff. To build a rebreather just add gas *anywhere* and stick the sensors *anywhere* and it'll work just fine. Water trap, no water trap, 02 injection in the inhale side, 02 injection on the exhale side, all that *crap* is just that: crap. In *practical* terms it makes no difference. Add your 02 to the inhale side and spike *one breath* of gas to a higher PP02 every now and then? Big deal..... Just forget about it.

LAR-V is the best chest mounted 02 rig to modify. Best scrubber, etc. C-96 is a second choice substitute. I've also done a few of the French rigs (Spiro) that came out of Iraq, etc. They are work the same way. Select the best *scrubber* and then stick the gas and the sensors wherever they fit.

C-96 availability ought not to be a problem. I never had a problem buying one when I needed one. There are loads floating aroundm, just keep your eyes open. I used to buy them mail order from Italy, where 02 rigs have been more commonly used by sport divers for many years than any other place. Google the Italian Language sites and I bet you come up with one.


Dave

__________________
"Silent Diving with No Bubbles and No Politics".... www.nobubblediving.com

OceanOpportunity

thanks Dave,

still interested in taking a look at your rig in narragansett sometime...let me know your availability, as I'm entirely flexible

Mike

jaap

OK you are probably right. But I find it a bit scary when the meters go off the scale now and then for a few breaths if the O2-add and cells are in the same bag. Sure if the KISS-valve is set very close to the O2-consumption and O2-bypassing is not required so often the spikes are not that bad.

Also what is the true inpired pO2 level? If one does not care about +-0.2 well then I guess any arrangement is fine.

I did some experimenting having the KISS-feed in the exhale or inhale bag having cells in both bags looking at the difference during some dives.

I found that if the cells are close to the KISS-flow the average pO2-displayed can be significantly higher (say about 0.2-0.3 higher) compared to the other bag. This is exluding spikes related to bypassing. So if I can chose I would prefer to have the cells close to the inhale and the O2-feed close to the exhale side.

OK so lets forget about watertraps but if the bag and cells are on the exhale side the CO2 will affect the PO2-reading. Not a big thing but there would be some depth dependent pO2-offset.

Dave, out of curiosity what is your accepteable pO2-interval to maintain with this kind of CCR? I guess if one does not care to much about holding a tight pO2 then I really doesn't matter much.

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