[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [PSUBS-MAILIST] Humidity control



Sodasorb and Sofnolime are very similar products chemically, and more 
importantly, they both contain a certain amount of moisture as supplied from 
the factory.  Thus, the scrubber media is not completely ineffective when the 
process air is at 0% RH because the CO2 can still go into solution and form 
carbonic acid in the hydrated absorbent.  Depending on how tightly that water 
is bound to the absorbent chemicals, it is conceivable that running 0% RH air 
through the scrubber for an extended period of time could dry out the material 
and eventually render it ineffective, but low RH is not generally a concern in 
submersibles.  I was just speculating as to the actual effectiveness of the 
scrubber media as RH varies - it makes sense that higher RH would correspond 
to higher reaction rates given the greater capacity for dissolving CO2, but I 
haven't actually seen test data from the manufacturers to confirm this.

-Sean


On Wednesday 16 March 2011 16:36:24 you wrote:
> In a larger cabin such as the K-boats the air purge shouldn't be as much
> of an issue due to the larger volume of air.  It's also not clear
> whether such a purge would be efficient enough to bring the RH to
> near-zero even in a cabin as small as the R-300.  Assuming it did bring
> RH down to 20% or so, the question becomes more about how much water
> vapor sodasorb (or similar product) requires to activate CO2 capture.  I
> don't know if that data is available from any product specifications.
> 
> Jon
> 
> On 3/16/2011 3:38 PM, Cliff Redus wrote:
> > Sean, I also think this is true also.  I have a relative humidly
> > sensor in my boat.  When I did an 8 hour test in my boat in which I do
> > not have any RH control,  at the time the hatch was closed, the RH was
> > 50%.  After about one hour, the RH climbed to around 80%.   Over
> > the next 3 hours, the RH climbed to 85% and stayed at this level for
> > the duration of the test.  This leads me to believe that the primary
> > source of condensed water vapor in the boat is due to exhalation of
> > 100% RH air.  I think that purging the pressure hull with dry air
> > prior to hatch closing would bring down the initial RH to near zero
> > but quickly for a small psubs like mine, it would climb rapidly.  As
> > the chemical reaction in the scrubber needs water vapor to work, this
> > concept would seem to me to be counter effective to scrubber operations.
> > In the spirit of KISS, I am not sure it makes sense to try and
> > condition the air to regulate RH anyway.
> > Cliff



************************************************************************
************************************************************************
************************************************************************
The personal submersibles mailing list complies with the US Federal
CAN-SPAM Act of 2003.  Your email address appears in our database
because either you, or someone you know, requested you receive messages
from our organization.

If you want to be removed from this mailing list simply click on the
link below or send a blank email message to:
	removeme-personal_submersibles@psubs.org

Removal of your email address from this mailing list occurs by an
automated process and should be complete within five minutes of
our server receiving your request.

PSUBS.ORG
PO Box 53
Weare, NH  03281
603-529-1100
************************************************************************
************************************************************************
************************************************************************