Elephant trunk ventilation systems

Clare Manias <cmanias [at] mobia__org> writes

>I am considering an elephant trunk style fume extractor vs. a small
>portable unit for use in a very small conservation lab. ...
>...
>
>I am interested on feedback from anyone who uses an elephant style
>fume extractor, what are its most useful features and its drawbacks,
>and what flow of air would be recommended for the extraction of
>solvents and cleaning of mold.

I've used fume extractors of both types and both have their place.
Both are designed primarily for and work best catching and removing
lighter than air volatile solvents. Portable units are quiet,
relatively inexpensive, and easy to put out of the way when not in
use.  I've used some made by Nilfisk which consist of a trunk
mounted on a wheeled stand with a large activated charcoal filter
designed to absorb organic vapours.  These are great for occasional
use, but the problem is knowing when to change the filters- which
are relatively expensive.  There is no meter or gauge to tell you
when the filter has reached capacity and needs renewing. We later
installed overhead trunks with a ceiling mounted rail which were a
lot more industrial, and a lot noisier, bigger and more imposing.
These suck your room air out and if you are conditioning that air,
you are losing a lot of it.  If you retrofit such a unit, you will
need to consider whether to install a make-up air unit- which gets
complicated and expensive.  These units are made for industrial
users and sold by people who are more knowledgeable in that area
than in our field- it would be rare for a conservator to use the
amount of volatile material these units are designed for- and
installation may also trigger the interest of regulatory authorities
who must presume you are using them to their maximum capacity and
will impose conditions appropriate to that assumption. But your
biggest problem is neither is great for removal of mould from the
air- they just won't catch it efficiently.

If your main issue is mould, and especially if your space is quite
limited, I'd suggest you consider a cupboard type arrangement where
air comes in the front of the unit and is drawn across the work
surface away from the operator towards the back and either vented
out of the room or drawn through a HEPA filter and recirculated.
This is probably something you would have to have made up, but isn't
at all complicated.  Do be careful not to call it a Fume Cupboard as
that is a specific device which is highly regulated in most cities
and not what you are actually needing unless you are also dealing
with substantial quantities of flammable solvents and/or toxic
chemicals. You want a gentle air flow- high volume, but low
velocity.  This will be quiet and will do the job more than
adequately.

Tom Dixon
Melbourne Australia


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                  Conservation DistList Instance 24:14
                  Distributed: Monday, August 30, 2010
                       Message Id: cdl-24-14-005
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