Standard 80cft side-mounted tanks for CCR?

[tbone1004]

Based on what I understood from the OP this was 1x 80 of dil/out and 1x 80 of O2 (which I guess would be for both the CCR and deco)

SCR with something like 15/55 is serious business.

agreed, but I think the OP was talking about OW diving where I don't know if I'd bother with redundant dil where we somehow switched to cave diving where the priorities are obviously different

 

[rjack321]

agreed, but I think the OP was talking about OW diving where I don't know if I'd bother with redundant dil where we somehow switched to cave diving where the priorities are obviously different

well in OW I don't think its a big deal to do the single dil/BO thing. IF you have some sort of redundant wing /suit gas for buoyancy.

Losing dil/bo and having nothing to inflate with in OW would be bad.

 

[fsardone]

well in OW I don't think its a big deal to do the single dil/BO thing. IF you have some sort of redundant wing /suit gas for buoyancy.

Losing dil/bo and having nothing to inflate with in OW would be bad.

Right!
That happened to me by running out of inflation gas and it is not fun, had to plug offboard dil in wing ...
And at that time I had:
-air for wing and suit
-onboard dil (plugged in MAV and ADV)
-offboard bailout (pluggable as dil and wing gas)

Due to this, I did slightly alter my config so I can easily plug onboard dil in wing and also offboard dil has an easier way to plug in the wing ...

I would not dive with only one reg for my diluent and have no redundancy for buoyancy ... people have died for lack of access to OC gas (tear in the corrugated hose while climbing the ladder and falling in the water negative) while no way of inflating suit/wing.

 

[jale]

well in OW I don't think its a big deal to do the single dil/BO thing. IF you have some sort of redundant wing /suit gas for buoyancy.
Losing dil/bo and having nothing to inflate with in OW would be bad.

And why shouldn't we dive a balanced rig as in OC?
Shouldn't we able to manage going up even with no dil? Shouldn't we able to use the CL as "buoyancy devce"?
Of course to have redundancy is better.

 

[jale]

people have died for lack of access to OC gas (tear in the corrugated hose while climbing the ladder and falling in the water negative) while no way of inflating suit/wing.

Sorry but I don't understand.
You mean a tear in the loop AND no inflating possibility. Bad day!

 

[rjack321]

And why shouldn't we dive a balanced rig as in OC?
Shouldn't we able to manage going up even with no dil? Shouldn't we able to use the CL as "buoyancy devce"?
Of course to have redundancy is better.

if you only have one source of dil which is also your BO and suit and wing, and that single regulator fails you are having a bad day. If you're near a anchor or mooring line or have a slope to ascend ok not so terrible. No deco obligation is super helpful, kick up and you're good. If your CCR is flooding or have to bail for any reason, and/or you have any kind of deco obligation you are stuck, at depth, heavy, with only O2 to breath. Just ascending to 6m with nothing to breath, no wing or suit gas, is going to be miraculous.

My CLs are nowhere near large enough to keep my neutral with 2 al80s on. I am weighted to stay down if I use all the BO. That's about 10lbs of gas or 5-6L EXTRA in my CLs.

 

[moose_grunt]

Didn’t Advanced Diver Magazine have an article about just what the OP is talking about? I seem to remember it being about a couple of different “expedition” setup scenarios, one of which was no onboard, and off board dilout and o2 side mounted.

*edit* found it: page 36
Advanced Diver Magazine • ADM Ezine Issue Four


I’ve been playing with a similar but different scenario—mounting LP50s to my unit, not manifolded, with dilout on one side and o2/deco on the other. Using H-valves or Lola valves, could have two regs and some redundancy there, but would still be screwed if I lost a neck O-ring or burst disk.

Jim

 

[jale]

if you only have one source of dil which is also your BO, and that single regulator fails you are having a bad day. If you're near a anchor or mooring line or have a slope to ascend ok not so terrible. No deco obligation is super helpful, kick up and you're good. If your CCR is flooding or have to bail for any reason, and/or you have any kind of deco obligation you are stuck, at depth, heavy, with only O2 to breath. Just ascending to 6m with nothing to breath, no wing or suit gas, is going to be miraculous.
My CLs are nowhere near large enough to keep my neutral with 2 al80s on. I am weighted to stay down if I use all the BO. That's about 10lbs of gas or 5-6L EXTRA in my CLs.

I was not talking of having two failures at the same time
Losing your Dilout and having a flooding, this is really a bad bad day
I was talking about losing your Dilout only.
If you lose your Dilout in OW, it shouldn't be a problem to come up if your rig is properly done.
Now if I have a flooding (without having a dilout lost), I don't see the problem either as my RB is ditchable if needed.
If I have a lost dilout AND a flooding, well...

 

[Bernie_U]

I left the thread for a while since I cannot add anything to the statements regarding specific rebreather models. Now, moose_grunt mentioned an article in the Advanced Diver Magazine and I would like to ask whether it might have been this one.

So far, I got: It is possible to operate a CCR with off-board gas only, similar to the Mares SCR, which has no on-board tanks at all. (As an SCR is just a gas-extender, small (3 litres) on-board tanks are too small.) Normally, the small on-board tanks are fine, but can be an issue when traveling.

Now, the discussion has moved on to the question, whether it was safe to use two AL80 without any on-board tanks. The diluent tank is supposed to supply the CCR and to serve as bail-out. A recent thread in another SCUBA forum concluded that it is unwise in an overhead environment. Provided a single failure only, you can either return to surface on bailout, or in the loop, depending on what broke. For cave diving, they linked a TDI article that might help.

 

[jale]

I left the thread for a while since I cannot add anything to the statements regarding specific rebreather models. Now, moose_grunt mentioned an article in the Advanced Diver Magazine and I would like to ask whether it might have been this one.
So far, I got: It is possible to operate a CCR with off-board gas only, similar to the Mares SCR, which has no on-board tanks at all. (As an SCR is just a gas-extender, small (3 litres) on-board tanks are too small.) Normally, the small on-board tanks are fine, but can be an issue when traveling.
Now, the discussion has moved on to the question, whether it was safe to use two AL80 without any on-board tanks. The diluent tank is supposed to supply the CCR and to serve as bail-out. A recent thread in another SCUBA forum concluded that it is unwise in an overhead environment. Provided a single failure only, you can either return to surface on bailout, or in the loop, depending on what broke. For cave diving, they linked a TDI article that might help.

The article you linked in ADM is really an old one as they have a advertising for the Armadillo harness...long ago and I don't think moose was refering to that one.
Regarding CCR with offboard, it has been "advertised" before by some manufacturers. If I remember correctly, the Pathfinder was one of them: O2 on-board and dilout.