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Subject: Dataloggers

Dataloggers

From: Richard Fuller <frichard<-a>
Date: Tuesday, December 18, 2007
Kathleen A. Malarkeys <kmarkees [at] wpi__edu> writes

>I was hoping for a more extensive discussion of data loggers. Does
>anyone have comments on the humidity and temperature data logger
>made by Extech?  ...
>...
>...  Also, any advice/tactics
>for convincing higher-ups of the importance of controlling
>temperature and humidity ...

I can't comment on the Extech products because I haven't used them
but I'd like to contribute a few general comments. Although there
are other considerations of long term reliability, warranties,
calibration, sensor replacement, flexibility and readability of
downloaded data, the accuracy of moderately priced dataloggers is
probably entirely adequate for describing daily fluctuations and
seasonal change patterns, for a wide range of collection materials.

Patterns of change are as important as refinement of the numbers. Of
course, you will have to produce data that is credible, especially
if it becomes a 'who has the right numbers?' showdown when
facilities maintenance, or contracted staff, bring along their own
testing equipment to confirm conditions you've presented. They will
likely view their own monitoring equipment as being infallible, so
be ready.

If cost is a concern, try the lower priced instrument that can
provide comparable performance to recommended brands (the Hobo
product, for example). Check the manufacturer's specifications--in
particular, the 'plus or minus' accuracy figures and over what RH
and Temperature range these apply to. Some units come with software;
for others, it is an additional one-time cost. Make sure you are
getting an 'apples to apples' comparison. Purchase one and try it
out for a few months to see how it works for you.

Although an added cost, it is a good idea to purchase a good quality
digital psychrometer to test readings of dataloggers, or for general
spot tests within the environment.

In my experience, specialized scientific equipment suppliers may
offer lower prices than general archival suppliers. Don't ignore
battery-powered, mechanical hygrothermographs if they become
available to you. They provide the same useful data, are reliable
(I've used them for over twenty years without a single failure),
accurate if maintained properly, can be user-calibrated (often, not
possible for dataloggers) and the information is always immediately
available to view (not always the case with dataloggers). The
downside is that you will have to buy charts and pens, which are
getting pricey.

As far as convincing administrators of the importance of the
collections' environment: after gathering the environmental records
you hope to provide, present your concerns within a Risk Management
approach (a language management may better understand). Prioritize
your collections in terms of vulnerability and sensitivity to
environmental change and extremes, in addition to other potential
hazards to your collections. Have collection examples on hand as
evidence of damage or deterioration and be well-informed of current
information and research on the subject, with predicted rates of
deterioration over time at varying relative humidity and temperature
levels. Arranging visits for "higher-ups" to see institutions with
superior environmental control, with accompanying awareness of its
importance, can provide a 'status and responsibility' incentive
which may lead to a reconsideration of the significance of a better
environment for your collections.

Richard Fuller
Conservator
Doon Heritage Crossroads
Region of Waterloo


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                  Conservation DistList Instance 21:37
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Received on Tuesday, 18 December, 2007

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