I agree with all that Harry has said. We used ductless hoods extensively
when weighing particulate actives. We never used them when solvents were
involved. Period.

Bob Alaimo

-----Original Message-----
From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**LIST.UVM.EDU] On Behalf Of
Harry Elston
Sent: Saturday, July 07, 2007 10:54 AM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: Re: [DCHAS-L] Ductless Fume Hood - need information

Generally speaking, Melissa, I am not a big fan of "ductless hoods"
primarily for the reason that Jim Kaufman mentions in his post,
"...when used properly."

Ductless hoods rely on filtration technology to remove contaminants
that are generated in the hood, be they an acid vapor, solvent vapors
or particulate.

The problem that I've run into the most regarding ductless technology
is user discipline.  When used in a research environment researchers
tend to focus on research instead of safe use of engineered systems
like hoods.  For example, a researcher will substitute solvents in a
hood without giving a second thought that the absorbing material
(i.e. filter) has a higher affinity for the new solvent than the old,
and therefore release some portion of the previously filtered
material.  If you want a hard-core chemistry example, think
"ion-exchange chromotography."  It's the same principle.

The other problem is going to be who is going to monitor the system
to ensure that the filters are still working?  Will it be you?  Do
you have the right training and technology to do that?  What will be
the filtration change-out schedule?  How do you know that whatever
you pick will be safe and effective?  Are you going to perform
periodic air monitoring to ensure that the filters are still working?

Jim Kaufman is absolutely correct that ductless technology can be a
good substitute for ducted hoods with the all important caveat - when
used properly.  Ducted hoods, when working correctly are much more
"chemist-proof" and generally speaking provide fewer headaches
(figuratively and literally) for the user or supervisor.

Harry



>
-------------------------------------------------------------------
>In a message dated 7/6/2007 3:39:20 P.M. Eastern Daylight Time,
>melissa**At_Symbol_Here**melgetz.com writes:
>
>I have been asked to look into using a portable,  ductless fume hood, and a
>ductless chemical storage cabinet for the chem lab.
>Do you have any  experience with ductless systems?  If so, please share
your
>opinions,  suggestions on which ones to get or not get, etc. Which filters
>should we  buy?  Do we really need a filter for organic materials?
>Do you know how  often the filters would need to be replaced?
>The ductless fume  hood is for regular chemistry classroom use.  The
chemical
>storage  cabinet will be in a room separate from the classroom and will
hold
>chemicals  for chem., bio, and other science classes.
>If you need more clarifying information, please  ask.
>Thank you in  advance for helping out with this decision making  process.
>Sincerely,
>Melissa  Getz
>_Melissa**At_Symbol_Here**melgetz.com_ (mailto:Melissa**At_Symbol_Here**melgetz.com)
>
>         -----------------------------------------------------------------
>
>
>James A. Kaufman,  Ph.D.
>President/CEO
>
>Laboratory Safety Institute  (LSI)
>
>
>Safety in Science and Science Education
>192  Worcester Road, Natick, MA 01760
>508-647-1900 Fax: 508-647-0062 Cell:  508-574-6264
>Email: jimkaufman**At_Symbol_Here**labsafety.org
>Web Site: _http://www.labsafety.org_ (http://www.labsafety.org/)
>
>Making Health, Safety and the Environment an Integral
>and  Important Part of Education, Work and  Life.
>
>*************************************
>
>
>
>************************************** See what's free at
http://www.aol.com.

+++++++++++++++++++++++++++++++++++

Harry J. Elston, Ph.D., CIH
Principal - Midwest Chemical Safety
www.midwestchemsafety.com
helston**At_Symbol_Here**midwestchemsafety.com
217.971.6047

Editor, Chemical Health & Safety
www.elsevier.com/locate/chs
http://membership.acs.org/c/chas/

"When a committee is in charge, no one is in charge."
	Elston's management axiom #3

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