Thursday, September 20, 2012

Desiccant Wheels

As a book conservator I was trained to dis-bind, wash, mend and re-sew books from different points in history.  However, a library's storage environment also plays a crucial role in the longevity of collections.  There's little to be gained from spending hours and hours treating a rare book if you have to send it back to a stacks area that is not up to par.
Facilities staff will always have the primary responsibility for maintaining the air handling systems, but it is important that librarians are engaged and articulate about the systems that take care of their books.  So a significant portion of my training focused on building systems, including heating, ventilating and air-conditioning (HVAC).  We had a final workshop on HVAC systems that reviewed different types of HVAC technology and concluded with a walk through of the air handlers in our classroom building. 

One of the technologies that was new at the time (1998) was using a desiccant wheel for de-humidification.  Have you noticed the little silica packets that come in boxes of shoes or electronics?  They're like that but much, much bigger.   

All of the buildings I've worked in 'til now have been older buildings with older types of HVAC systems.  My current job has been my first opportunity to see a desiccant wheel up close and I must say it was pretty exciting.  You can gete a sense of how big the wheel is from the picture above.  The yellow strap is the drive belt for the wheel, to keep it turning so that the unsaturated section of the wheel is in the airflow from the building while the saturated part is getting dried out. 

The wheels do get changed when they wear out as you can see below.  They're very, very heavy, so it is a good thing they roll.

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