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Subject: Elephant trunk ventilation systems

Elephant trunk ventilation systems

From: Jeffrey Maish <jmaish>
Date: Monday, August 6, 2001
Heather Place <conservator [at] wag__mb__ca> writes

>We are currently undergoing upgrading to our conservation lab, and
>after years of our fume extraction system not functioning correctly,
>we are working to rectify the problem. We are currently looking at
>ways to improve our existing elephant trunks and were wondering if
>anyone has any suggestions.
>Is there anything new on the market that anyone has experience with?
>I have heard that they now come with lights on the end. This would
>be very helpful.

We've installed a few ducting systems (for objects) and, in my
experience, the actual trunk comprises the tail end of the system.
I would focus more on the fan and ducting.  The fan has to be of the
right strength to get the air speed you need, and the ducting has to
be put in place with correct joins and bend angles.  Otherwise you
will get turbulence and lower air speed.

There are some good hints in "Safe Laboratories"  edited by Ashbrook
and Renfrew. Some very general rules would be to keep the duct
diameter large until you get to the point of connection to the
trunk, and to keep the angle of branch entries to the main duct at
30 to 60 degrees, and not 90 degrees.  Also, duct branches should
never be opposite one another off of a main duct.  Elbow bends
should be very gradual as should changes in duct diameter.  Also,
the points of connection for the trunks (to the branches) should be
in positions that are far enough away from the work area so that you
get coverage, but don't  "bunch up" the trunk hose with sharp angles
which also cut down on flow.

In some tests we did with trunks,  the extraction of solvents fell
off rapidly once you moved beyond a foot from the solvent source.
You can buy hood extensions  which will help confine the air flow a
bit, but your air speed still falls off dramatically (exponentially)
if you move the trunk further away. Having a light at the end of the
hood (on a grill)  also cuts down on air flow. For large surfaces
(covered with solvents) you might need something entirely different,
however, such as a fume hood (wall).   Its a compromise, but I think
if you have good ducting and a quiet fan location, the higher air
flow won't make as much noise, and I don't think would ever get to
the point of sucking more than the occasional cotton ball up the

Jeffrey Maish
Associate Conservator of Antiquities
The J. Paul Getty Museum
1200 Getty Center Dr. Suite 1000
Los Angeles, CA  90049-1687

                  Conservation DistList Instance 15:15
                 Distributed: Wednesday, August 8, 2001
                       Message Id: cdl-15-15-003
Received on Monday, 6 August, 2001

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