[Nhcoll-l] Humidity in collection rooms

[John E Simmons]

Most of the fire safety regulations for ethanol are based on either storage
of retail liquor (rarely more than 40% ETOH) or bulk storage of
full-strength ETOH in drums. I have never found a study that looked at the
fire danger from 70% ETOH in a museum situation. Alcohol flash points are
carefully calculated, of course, but the application of flash point to
storage is theoretical, e.g., sparking from overhead lights is unlikely to
trigger a fire in most museum storage situations because ethanol fumes
dissipate quickly and accumulate at floor level. It would take a massive
leak or spill in most situations to create a fire or explosion hazard
(except for below-grade storage). That said, 70% ETOH ignites easily and
burns very hot, so we must be cautious in our storage arrangements and
eliminate all sources of ignition that are practical to eliminate. For
example, it makes sense to eliminate wall sockets so no electrical
equipment can be plugged in inside a fluid storage facility, but requiring
spark-proof light fixtures is probably overkill for above grade storage.

As for storage relative humidity, I agree with what others have said about
temperature and (more critically) stability and dew point. You need to be
able to reduce temperature and RH fluctuations as much as practical. The
effect of RH on evaporation depends, in large part, on what sort of seals
your containers have (hence you should emphasize reducing leakage from
individual containers). In general, avoid RH close to 60% or higher because
that means only a small increase will get you into the mold growth range.

The free dew point calculator available from IPI is extraordinarily useful
for planning storage temperature and humidity for any museum collection:
http://www.dpcalc.org/

--John

John E. Simmons
Writer and Museum Consultant
Museologica
*and*
Associate Curator of Collections
Earth and Mineral Science Museum & Art Gallery
Penn State University
*and*
Investigador Asociado, Departamento de Ornitologia
Museo de Historia Natural, Universidad Nacional Mayor de San Marcos, Lima


On Fri, Jun 25, 2021 at 10:58 AM Callomon,Paul <prc44 at drexel.edu> wrote:

> I’d be interested to know if there are any published studies of the spark
> ignition of ethanol vapors – perhaps others would too, so if you know of
> any - chime in! My experience with other volatiles, such as gasoline, is
> that spark ignition is unlikely once even a moderate amount of dissipation
> in air has occurred, but also that such vapors can create “trails” in
> still, dense air (linking, for example, the pouring point with the spot at
> which the container was put down and capped).
>
>
>
> *Paul Callomon MSc*
> *Collection Manager, Malacology and General Invertebrates*
> ------------------------------
>
> *Academy of Natural Sciences of Drexel University, Philadelphia*
>
> 1900 Benjamin Franklin Parkway, Philadelphia PA 19103-1195, USA
> *callomon at ansp.org <callomon at ansp.org> Tel 215-405-5096 - Fax 215-299-1170*
>
>
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