wreckdiver68

This looks like an interesting idea. It looks like it's already been mentioned but water absorbsion of the media from exhaled gas is going to be problematic to account for.

One way to help account for it might be to run some control tests with expended sorb (non diving obviously) to remove the variable of the reaction. This should allow you to get a rough idea, probably still underestimating, of the amount of weight increase due to the amount of water absorbed by the media.

By assembling your rig with the inhale hose disconnected you should be able to expose the scrubber to exhaled gas w/ 100% humidity without the risk of hypercapnia.

The only other variables should be the specific rig/canister, and ambient temperature. After drying out a bunch of used sorb and packing a scrubber, one would only need to weigh it at set intervals, dry, then maybe every 10 minutes, until until the weight levels off.
Repeating the test with the same sorb a couple of times will help insure that your not actually measuring weight increase due to CO2 absorbed.

In actual use I would imagine you would get more weight due to condensation but you might be able to get a little closer to what you want while still maintaining a reasonable safety margin.

Running the test in different ambient temeratures should allow you to create charts plotting time on the media vs. weight change due to humidity of the media/condensation at different temperatures.


Regards,
Owen