[PSUBS-MAILIST] scrubber performance

Fri Feb 17 12:27:16 EST 2017

I don't think insulation is needed, based on the fact that Gamma never has had insulation.  Gamma did a dive mission in Alaska where it would have been an issue.  I also think that the absorbent exothermic reaction produces its own heat.  I know you mentioned that the cool air flow would negate that effect.  I think the exothermic reaction may start at the core of the granules and the heat moves outward, that in conjunction with the fact that there is a thick layer of granules acting as insulation, this will keep it warm enough to maintain efficiency.  The cool airflow will of coarse reduce the temperature, but it likely stays warm enough.  The proof is in the fact that the scrubber works at very low temperatures with cool air flow.  The performance improves after a period of warm up time, that means the absorbent is increasing in temperature despite the cold environment.  Surprisingly, Gamma is not a big old sweaty sub, there is not a lot of water forming on the hull, and only seldom do I have to wipe the ports\dome from fog.  Usually shortly after I am at the bottom do I need to give a wipe and only once.  I would conclude that since there is only one body of air, the moisture is released right away and that is the end of it.  Also doesn't the scrubber use up moisture - I thought I read an article by Dr Nuytten that said a submarine was an ideal environment for a absorbent based scrubber.   Also I am guessing at the temperatures, I will make a point of recording temps and Humidity levels.A word of advice, don't drink coffee in your sub after age 50, you will need to pee often.  You could sail right over the treasure chest fumbling for the PRBHank 

    On Friday, February 17, 2017 8:43 AM, Sean T. Stevenson via Personal_Submersibles <personal_submersibles at psubs.org> wrote:

  I don't recall seeing insulation in the DW2000 either.  Perhaps Phil will chime in on this?  It is possible that being so compact, the surface area of the DW hull is small enough that the contained heat loads can keep up to the moisture production.  Also, those are certified through GL, and as such may have different requirements than ABS's 30% - 70% RH.  Can anyone speak to the GL rules on this?  I can't see avoiding a 100 % RH environment, and the consequent condensation, when submerged in 5°C water without either insulating or employing dessicants to remove the moisture.  Immediately next to the hull, it will always be colder, so you may get condensation on the hull despite being within humidity limits on the cabin air on average.  I was thinking that a cylindrical pressure hull would be relatively simple to insulate though, with something like AP Armaflex sheet material.  You wouldn't even necessarily need to apply at 100% coverage, but rather just enough to reduce the heat loss to meet the 70% RH limit at whatever your cabin temperature is. (14°C - 30°C are the recommended temperature limits, but that's not actually a rule under ABS UWVS). Insulating just the large cylindrical surfaces between frames might be sufficient.  In my own design, insulation is a necessity - otherwise I won't be able to keep my coffee hot.

 Sean

 On 2017-02-15 17:41, hank pronk via Personal_Submersibles wrote:

  Sean, I can not remember the temperature over the length of a typical dive.  I would estimate 10C after 1\2 hr at 100 feet.   When I dive Kootenay  lake it is probably 5C  I wonder how DW's manage, they dive all over the world and I am sure in the winter. Hank

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