Dessicant and fan for drying rebreather loop

[ChrisMBC]

In my endless quest for optimization, I'm thinking about how I can dry the loop of my JJ most efficiently/effectively (preferably without breaking down the entire unit). I've seen a few options for loop drying that use a fan pointed at either the head or straight into a counterlung, but now I'm wondering - is there any reason I couldn't use a closed-loop drying process, essentially replacing the canister of sorb with a canister of dessicant, and using a fan (or series of fans) to push the gas through the loop?

Essentially, this would mean building a replacement for the canister that:
- Contains dessicant
- Has a fan that pulls the wet return gas through the dessicant, and then up through the inhale hose
- Has its own power supply (and potentially monitors for humidity on the intake and exhale sides).

Are there any gotchas that I'm not thinking of here? Particularly curious if anyone thinks circulating dessicanted air would pose any health or component risks, or if the general constant circulation of gas would do bad things to the flapper valves.

 

[rjack321]

Would definitely avoid flapping the flappers for days
Just rinse and hang the loop like a normal person and per manufacturer instructions rather than inventing a new way to give yourself a fungal lung infection or whatever

 

[davehicks]

It's really easy to overthink this. Just hang things up and put them in front of a desk fan. Just a little air movement, time, and maybe some ventilation if indoors is all that is needed. In 24 hours, everything will be fully dry.

You only need things to be 100% dry when putting things in storage for weeks or months to avoid mold and mildew. If you are diving within 24 hours, it does not need to be totally dry. As soon as you start diving it's going to get wet again anyway.

 

[ChrisMBC]

Would definitely avoid flapping the flappers for days
Just rinse and hang the loop like a normal person and per manufacturer instructions rather than inventing a new way to give yourself a fungal lung infection or whatever

But what's the fun in that?!

 

[Mobulai]

Contains dessicant
- Has a fan that pulls the wet return gas through the dessicant, and then up through the inhale hose
- Has its own power supply (and potentially monitors for humidity on the intake and exhale sides).

So your building a.. counter-rebreather for the loop/CL?

absolutely overkill unhinged mad scientist vibe off of this! I’m here for it, not a bit of sarcasm! I love it and would wanna see that as a product

But regarding the gotchas.. I can’t say
I’d buy a used dsv/loop hoses and CL (random and cheap) to test stressing the valves before.. but you gotta kinda build it 1st

 

[ChrisMBC]

So your building a.. counter-rebreather for the loop/CL?

That’s pretty much what I’m thinking, yep. I can’t think of a ton of reasons it won’t work, and it would let me rinse and then dry the rebreather entirely on the stand. Also, frankly, I think it’s hilarious to turn it from a CO2 scrubber into a water vapor scrubber.

 

[justinthedeeps]

I'd prefer to encourage water to drip down and out of disassembled things, rather than to dry residuals in place. Forced air blowing an intact unit with inadequate flushing and draining to save time could result in buildup of salts and residues, wether organic or inorganic. That stuff will then mold eventually, regardless of how temporarily dry it got.

Also if you need it -that- dry, it is for storage, which means a lot of the unit should be disassembled anyway. I guess you could blow dry some near at the end.

The 'time saver' for regular diving is dunk sealed unit in large rain barrel (or pool, lake, stream etc) full of reusable decently fresh water, take loop and head out, steramine flush/rinse, hang the intact lungs/wing/plate/frame assembly inverted from hooks/brackets/clips to improve lung drainage and drying. It will be dry enough for the next dive(s), and if it's well rinsed and open to decent air then mold is unlikely to develop in the meantime.

 

[ChrisMBC]

I'd prefer to encourage water to drip down and out of disassembled things, rather than to dry residuals in place. Forced air blowing an intact unit with inadequate flushing and draining to save time could result in buildup of salts and residues, wether organic or inorganic. That stuff will then mold eventually, regardless of how temporarily dry it got.

Also if you need it -that- dry, it is for storage, which means a lot of the unit should be disassembled anyway. I guess you could blow dry some near at the end.

The 'time saver' for regular diving is dunk sealed unit in large rain barrel (or pool, lake, stream etc) full of reusable decently fresh water, take loop and head out, steramine flush/rinse, hang the intact lungs/wing/plate/frame assembly inverted from hooks/brackets/clips to improve lung drainage and drying. It will be dry enough for the next dive(s), and if it's well rinsed and open to decent air then mold is unlikely to develop in the meantime.

The idea here is basically to do the first half of what you describe - exterior fresh-water rinse, rinse/disinfect the counterlungs and loop on the stand, pull the scrubber and dry/repack it, and add the 'water scrubber' to the head and dry everything else in place. Flipping the unit (in the GUE rig) seems kinda sketchy to me.

This whole project would be about 20% practicality, 80% fun. I was looking at loop drying fans that others have made, thinking about how I could dry the air going in (my basement is a little on the humid side in winter), and got carried away.

 

[justinthedeeps]

Flipping the unit (in the GUE rig) seems kinda sketchy to me.

My dunking and inverting is made easier by a rudimentary suspended hoist with mechanical advantage via pulley blocks.

I think this could work for even the heaviest of configs with cylinders left on, provided the right line/cable, attachment and hoist (perhaps even electric/hydraulic?)
Auto shops routinely hoist engines?

I see the appeal of forced air circulation for a heavy intact unit as you describe. It seems helpful as long as proper flush and drainage of residues is accomplished first (and the flappers monitored as pointed out by @rjack321 )

 

[broncobowsher]

The Desiccant bill might turn into the most expensive part of maintaining the rebreather. The stuff is for picking out water vapor, not liquid drops.