Recording hygrothermographs and dataloggers

Tom Dixon <tom.dixon [at] ngv__vic__gov__au> writes

>I would be grateful to hear from the list regarding positive and
>negative experiences of replacing recording hygrothermographs used
>for simultaneous monitoring of several large gallery spaces on a
>long term and continuous basis with newer technology.

I would like to make clear that my article on dataloggers in the
most recent AIC newsletter does not advocate getting rid of
hygrothermographs. I think for the institutional needs described by
Tom Dixon, hygrothermographs serve a valuable function. The key
question is what do you do, or want to do, with the environmental
data once you have collected it? Do you just file the charts away or
are you interested in doing more analysis of the data? For the new
galleries I might advocate a mixture of dataloggers and
hygrothermographs.

At the American Museum of Natural History this approach was used
effectively in new exhibition galleries. A recording
hygrothermograph was placed in an unobtrusive location providing the
easy visual check that you would like to maintain. We also placed
several dataloggers in key areas around the galleries (i.e. at the
center of the room, near an important vitrine, at the entrance and
exit). The hygrothermograph paper was changed on a weekly basis and
allowed us to note unexpected spikes and quickly check trends. Since
we had this frequent check, the dataloggers could thus be downloaded
monthly or even less frequently.

The advantage of including dataloggers in the gallery is that it
increases your ability to to analyze the data. Having the
computerized files allows you to easily compare graphs from one
gallery to another and to work up statistics and ranges in Excel for
different spaces over long period of times. This is important if you
want to develop a profile of different building areas and HVAC
systems. Different kinds of charts and graphs can then be printed
for administration, curators and HVAC staff. If you are not
interested in doing this kind of analysis stay simple and stick with
the hygrothermographs.

While some of the loggers have nice display functions and/or audible
alarms like the Tracker, none of the loggers will show you at a
quick glance a week's worth of data in the way a hygrothermograph
will. So, if that is a valuable feature for you I would continue to
use them. However, as hygrothermographs are expensive, you might
consider purchasing only one per gallery and then investing in some
less expensive dataloggers that can serve a number of purposes.

Rachael Perkins Arenstein
Assistant Conservator
Peabody Museum of Archaeology and Ethnology, Harvard University
11 Divinity Avenue
Cambridge, MA  02138
617-495-2487
Fax: 617-495-7535


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                  Conservation DistList Instance 14:47
                  Distributed: Tuesday, March 20, 2001
                       Message Id: cdl-14-47-003
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