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RE: GSBN:Re: Moisture in SBW
Lots of good ideas coming out here
I thought I would comment on the inert gas drying idea. The reason
nitrogen will promote drying is that it is bottled under high pressure
and water vapor is removed in the factory. In general it is very dry
and has a low RH. Any air that you can find with low RH will dry with
the same efficacy as Argon, Nitrogen etc, provided they all have low RH.
This air can be created by heating the air (thus dropping RH) or by
using dessicant driers (expensive but effective).
Mold growth peaks in the 65-90 F range. Above this temp, growth
actually decreases due to heat stress and fast drying. So blowing 75 F
air on the straw might cause some problems (cause of the heat) but not
much relative to ambient air and non-dry air. When I said warm air I
meant 120-160F supply which when it mingles drops in temperature
somewhat. I doubt that the warmth will accelerate mold relative to the
very fast drying.
Heating the interior plaster to 90 F and NOT ventilating might do just
what Derek says, so heating must be combined with sufficient air
movement to ensure drying.
Dr John Straube
Balanced Solutions Inc.
Balanced Solutions for the Building Industry
P: 519 741 7920
<a target="_blank" href="http://www.balancedsolutions.com">http://www.balancedsolutions.com</a>
From: GSBN [<a target="_blank" href="mailto:GSBN@...">mailto:GSBN@...] On Behalf Of Derek Roff
Sent: October 20, 2004 18:57
Subject: Re: GSBN:Re: Moisture in SBW
Item 3. Concrete loves moistur,e probably as much or more than straw
does. I am not surprised that you have found it also to be very wet.
Drying is a challenge, especially beginning in late October. Adding
heat, as John suggested, is a mixed blessing. It speeds drying, but
promotes the growing conditions for mold. Drying at lower temperature
can inhibit mold growth. However, this requires low humidity and lots of
air movement. Standard fans will move a lot of air, but not with any
pressure or penetration. The best available tools for drying that I
know of are woodworkers' dust collectors. Portable dust collectors can
be found for $100-$200. These radial blowers can suck and/or blow
against moderate static pressure. Therefore, they can move some air
through a bale, and get a little penetration in your drying. Depending
on the situation, using a duct to suck air from and through the straw to
be dried may be the most effective approach. Lots of air movement is
most important, whether you add heat or not. Drilling small holes in
the bales, perhaps 1" in diameter, might make it possible to increase
the depth to which you could dry the bales. Restuffing the holes
afterwards would be a simple task.
I've often wondered if injecting an inert gas under pressure could help
dry bales with deeper penetration and less risk of mold. Nitrogen and
carbon dioxide are inexpensive, and fairly inert. The bottles used by
welders are portable, and contain no water. Forcing the gas through a
damp bale, the gas would pick up a great deal of moisture from the straw
as it warmed to room temperature. I don't think this would be feasible
for large areas, but might be worth a try in a small, wet, complex
location. Since I haven't done this experiment, I wonder if the
nitrogen or CO2 might actually be food for some micro-organism. I would
bet that a truly inert gas like argon would be too expensive to use.