Fathom Gemini WOB on partially used scrubber

[Underwater Tourist]

but I also have a water trap in mine that keeps a lot of the lung butter (excess moisture) out of the exhale side

Any chance you could post a pic of the water trap you made? I want to bookmark it for myself and reference in later on when I get a sw/gemini style ccr.

 

[Whitrzac]

4 in total, one at top and bottom of each scrubber

too many.

1 on the top of the inhale side is all you want

 

[Mobulai]

Any chance you could post a pic of the water trap you made? I want to bookmark it for myself and reference in later on when I get a sw/gemini style ccr.

I think they were TecMe ones, he got his whole build here: Building a Sidewinder / Gemini rebreather clone - wrecklessdiver.com

Here is a screenshot from tecme.de under Kiss section

 

[JCM@Atlam]

Check your mouthpiece as well. I've had leaks from a tear on a mouthpiece and it does not show up in any pos/neg check.

Finally, I don't use scrims or filters at all. These could impact WOB. I don't have any issues with dust in the unit. The Kiss has a tight metal mesh on top of the canister, and I find that sufficient. I might have used a filter a few times when I first started CCR almost 20 years ago, and quickly found them to be superfluous. Other CCR units and design might require them, but not the Kiss Spirit. I think in ages past some Sorb formulations were a lot dustier than Molecular Sofnolime, which has very little.

Thanks. Recently changed the mouthpiece as it did have a split which resulted in a bailout

 

[JCM@Atlam]

I do not own a Gemini but I believe the scrubber size referenced above is not accurate.
The Gemini holds a total of 4.8 lb (2.2 kg) of sorb. Each scrubber is 2.4lbs / 1.1kg.

Someone feel free to correct me if this is not accurate.

I dive a Sidewinder/Gemini-type clone so I'm just giving you my own personal experience. For me - I will typically either rotate scrubbers (move inhale canister to exhale side and repack exhale side). I'm also comfortable going a bit longer without repacking but I also have a water trap in mine that keeps a lot of the lung butter (excess moisture) out of the exhale side. I also only use 2 dust filters on the top. I think 4 is overkill, at least for my particular rebreather.

If your typical dive is only ~90 minutes then you could get away with dumping the exhale cartridge, move inhale to exhale and repack the other scrubber if you wanted to be very conservative. You'd only have to pack 1.1kg of sorb.

If it were me I'd would also leave the scrubber out to dry for a bit. Actual scientific evidence (not people's feelings) shows that leaving a scrubber unsealed for a day or so will not negatively affect the CO2 removal capacity. If you're diving the next day simply leave it on the counter. I will usually leave the scrubber on my work bench overnight. If I'm not diving until next weekend then I'll put it in a sealed dry bag the next day.

See paper here: Storage of partly used closed-circuit rebreather carbon dioxide absorbent canisters - PMC

Another option. I'm saying this with a bit of a disclaimer as I don't own a Gemini and this is probably not recommended. One thing you could do if WOB is an issue is pack with 4-8 mesh. I'm saying this with the caveat that that this sorb is probably NOT approved for the Gemini and it will have less duration than typical 8-12 mesh. People can make their own adult decisions about what they consider safe but I know plenty of people who use 4-8 mesh in their Sidewinders.

Given the Gemini is rated for 5+ hours and I've heard as much as 11, I think my numbers were correct

 

[flymolo]

Water getting in through the dump valve when I was dumping gas from the lung, was probably also a factor

Are you primarily using the dump valve on the counterlungs to dump excess gas from the loop? That could also be letting water in.

 

[JCM@Atlam]

Are you primarily using the dump valve on the counterlungs to dump excess gas from the loop? That could also be letting water in.

Nah, only ever used it in training drills. Normally dump out of my nose

 

[macado]

Any chance you could post a pic of the water trap you made? I want to bookmark it for myself and reference in later on when I get a sw/gemini style ccr.

Sure. I can always bring this to a different thread since it's a bit off topic from OP's question but the unit was made by Martin at TecMe. I gave him a little input about how I wanted the exhale side.

The exhale side has a lid that prevents accumulation of spit / lung butter from entering the exhale scrubber. It won't help with a full-on flood but it stops a significant amount of water accumulation from things like loose lips/spit/drool from entering the exhale scrubber.

I had him design a newer lid where I put 4-5 chamois (absorbent cloth/sponges) to soak up some of the drool. It works quite well on longer dives.

This is a video without the chamois in the lid:
Video of lid with chamois installed:

 

[Mobulai]

Sure. I can always bring this to a different thread since it's a bit off topic from OP's question but the unit was made by Martin at TecMe. I gave him a little input about how I wanted the exhale side.

Would be awesome to have a new thread (or followup on the original build weite up) maybe.. a 6mo/year review
I have also been considering doing a similar commission with TecMe for a while

 

[grantctobin]

4 in total, one at top and bottom of each scrubber

Hazard a guess, but I bet if you only use one on the top of the scrubber you're inhaling from, most of your problem goes away. This isn't to rule out the guesses of the other posters, but more than one of those scrims is excessive. Was this what was taught in your course?

Also, your Gemini does not hold 4.4kg of scrubber.