Exhaust systems

The 1000 sq. ft. conservation lab at the Shelburne Museum presently
has an exhaust system that has 100% outside make-up air.  A fume
hood and 4 remote 8" trunks are ducted to the exhaust fan and
individually controlled by dampers. The make-up air is heated
through a gas furnace and ducted into the lab.  Two large wall
humidifiers maintain reasonable RH levels in the lab during the
winter. When the temperature drops below 10 degrees F, the furnace
and humidifiers run continuously whenever the exhaust system is
activated to try to condition the great outdoors being brought into
the lab.  To save energy and money, I am interested in modifying the
present system to include a recirculating/carbon bed filtering
option for removal of organic vapors during the winter months.  We
use very small amounts of organic solvents (acetone, ethanol, xylene,
toluene) probably on the order of 50 ml a day on cotton swabs, when
cleaning the varnish from a carousel animal,etc.,so I believe the
carbon bed would last for quite a while.

Does anyone have any experience with such a recirculating lab
exhaust system?  How well does it work? How often must the charcoal
be changed? How much charcoal is required? Who designed and
installed your system? Thanks,

Richard L. Kerschner
Dir. Collections Preservation
Shelburne Museum
PO Box 10
Shelburne, VT  05482
802-985-3348  ext 3361

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                  Conservation DistList Instance 12:57
                 Distributed: Tuesday, January 12, 1999
                       Message Id: cdl-12-57-012
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