cell holders within counterlung

OceanOpportunity

Hey gang,

I know there have been discussions previously, but what is the general consensus on using a 3-cell holder via a p-port within the counterlung? moisture issues? space issues? specifically, I am building (another) dolphin conversion and am considering this version of cell holder.

thanks for any input
ML

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Michael Lombardi
Oceans of Opportunity
www.oceanopportunity.com

Elected Director, Society for Human Performance in Extreme Environments

MN'07, The Explorers Club

Project Manager, Diving a Dream

Dsix36

With my very limited knowledge, I would be concerned with moisture. I would be even more concerned with having sensors that are suspended in a CL with the ability to "bang" around. They are pretty cheap little things to subject to much abuse.

I am sure that smarter divers will correct me and make me look stupid but there's my .02

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OceanOpportunity

I know that the in-the-bag cellholders were quite popular for some time. Both Narkedat90 and Tecme produce them. I wouldnt expect any more condensate type moisture than anywhere else in the loop, but my concern might be puddles collected in the bag. Anyone out there using one?...

the other concern is how much space they take up in the lung...are these things overbearing, or do they fit ok?

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Michael Lombardi
Oceans of Opportunity
www.oceanopportunity.com

Elected Director, Society for Human Performance in Extreme Environments

MN'07, The Explorers Club

Project Manager, Diving a Dream

Marc T

Im not using a cell holder on of my sidemount homemade but two cells hanging in the counterlung, of course each cell is protected in an individual small box and of course not hanging by the electric wire.
Neither had moisture problem on 3 hours dive, even neither seen any moisture on the sensible surface of the sensor immediatly after a dive.
Condense is on the counterlung NOT on the sensor.
I have of course a moisture pad in the counterlung
In this place the sensors are more protected from caustic than in the canister...with the sensors in the canister you can have the cells to be dead because of caustic but not yet any caustic in the Counterlung and the scrubber still working.
Had that several time so dont want the sensors in the canister anymore, anyway I actualy use the IDA71 canister with no exhale CL no water trap, believe me or not but the system is flood resistant an efficient.

If I had to use a three sensor holder in a CL I would try to have it in axial position ( mean long axis of the CL when it is flat )

Hope thats help

Dave Sutton

Having built or overseen some 120+ conversions to date, using cells in the CL works just fine. Condensation has never been an issue. The prototypical sensor holder that I designed, now as made by narked@90 (John) as the DS-3, has been well proven in the field and has been cloned by at least two other makers and is in widespread service.

For Dolphin, I made one with a hinge that folds the cells into the bag once it's inserted. Reduces tenting, and has been a charm. Complex to make, and not in commericial production anywhere, but I can send a photo if you like.

My holders have also included a gas injection port so as to simplify porting the lung for PP02 measurement and gas injection.


Theory is only valid insofar as it reflects reality. The reality is that this system has been just fine.


Dave

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dave t

I agree, I have run sensors in the inhale counterlung and they stay drier than in the lid.
I wonder however how much drift would be measured between M/peice po2 and lung po2 if the loop design is the "tee off the bag style"

In practise probably not much,

Dave have you measured this?




Dave

AD_ward9

Cells in CLs work fine, when the normal precautions are taken (i.e. no wells for water to sit in).

Humidity in the CLs is very slightly lower than in the scrubber head, due to it condensing with the fall in temperature.

The P-Port holder from Narked@90 works particularly well: I did not know that Dave did the first one of these, but nice to be filled in by his post below. It is nice and simple, no water traps on the outside of it, and inexpensive.

We have some larger P-Ports, that just about take an R22.

Alex

mwenner

Is there not a moisture barrier over the face of the sensor, and the differance between either location shouldn't cause a problem? I'm working on placing my sensors in a "head" I'm presently building (as Duncan had his D5 sensors in the one counterlung), using P ports, and was hoping to give my counter lung a bit more room to move, and generally more space in the 6" diameter tube. I've also come across a great circle guide, made by Jasper Tools, which made cutting a perfectly machined 6" (or whatever) disc, and the detent for the O ring in a matter of 1 minute. I'd sure like some more opinions of the sensor location in a "head" rather than the counterlung, since it's what I'm doing at the moment. I'd like to seperate the face of the sensors from the chemical, but have them directly in the loop, and with diluent drying them. Hope that makes someone's life easier, as visiting rebreatherworld has saved my life a few times.
mwenner's Images - Cave Diver's Forum Photo Gallery @ http://www.cavediver.net/forum/gallery

AD_ward9

There is a moisture barrier, but droplets will sit on the cell surface if they are facing upwards and they will have an extremely long response time. It is important they are not in a position where they face up or where there is a well that collects water and not drain out.

Blowing diluent on them may force water through the membrane if it is done hard enough. They only stand water with about 2lb of pressure, and a fast jet of gas will be more than that at the point it impinges.

Alex

divetheworld

When we started manufacturing the DS3 (Named after Dave Sutton) we also improved upon the original by using a cell protector. Pictures below.
Double 'o' rings is also a good feature that is not used on "clones".
Since then there have been a number of innovative variations including ones which use R22's and ones which fold over rather than point directly in.

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