Date: Wed, 21 Sep 2011 20:08:39 -0400
Reply-To: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: Ken Simolo <simolo**At_Symbol_Here**CHEM.CHEM.ROCHESTER.EDU>
Subject: Re: Fume Hoods
In-Reply-To: <B06FE04AACB936438D57258499897CD91630D6DAE5**At_Symbol_Here**>

I feel much more positive about the use of the latest Green Hood 
technology available from Air Master Systems Corp (Don Nelson, 
231.798.1111.ext 40).  We have not felt comfortable installing the 
standard charcoal filter ductless hoods but we have just installed 13 
Green Hoods in a less toxic situation than what you describe.  The 
savings are quite significant in installation and operation.  These guys 
make great conventional vented hoods as well as non-vented fume hoods so 
they do not push just one technology because that is all they have.

I take a balanced approach when evaluating what fume hood system to use. 
 There are obvious exceptions to what I can simply state here:  First, 
almost all exhaust air in most situations should be exhausted by fume 
hoods.  So standard room exhaust required for the necessary air 
exchanges in a typical laboratory should be exhausted through fume 
hoods.  Doing this lets you utilize the expensive makeup air for two 
purposes, air exchanges and fume hood exhaust.  After that, you need to 
make an assessment of the safety and costs of using various types of 
hoods.  One factor to take into account - if you create a mixed 
environment of hoods, how well can you train your researchers to use the 
appropriate hood for any given procedure and how responsible are they.  
In other words, will they use the right hood?

Looking at the compounds you mentioned, on a 6' Green Hood you would 
capture about a kilogram of carbon disulfide or sulfur dioxide before 
the first set of filters were breached and the chemical sensors went 
off.  There is still another kilogram of capacity in the filters after 
the fan and chemical sensors but I would treat the hood as no longer 
usable.  Knowing how much it can capture before a filter change is 
necessary, you can then evaluate the suitability for your own 
application.  They have tested the capture capacity for thousands of 
compounds.  Erlab really knew what they were doing when they developed 
these filters.  If you call Air Master Systems, they can do an 
evaluation of your needs and let you know which technologies will work 
well, conventional or their Green Hoods.  They sell both and I have 
never seen them push for a Green Hood where it did not make sense.

I was also impressed with the sensitivity of the sensors.  Besides the 
fume hood sensors, they also have a sensor in the hood to test the air 
in the lab.  The lab sensor went off when they were cleaning some lab 
benches with a solvent during installation.  There was not that much of 
an odor from the small amount of solvent but the sensors picked it up.

These Green Hoods are not suitable for all applications but they 
definitely have their place.  There are even some very unique nuisance 
situations where a conventional carbon filter ductless hood is an 
appropriate solution but I am much more comfortable with these Green 

Ken Simolo
University of Rochester

Previous post   |  Top of Page   |   Next post

The content of this page reflects the personal opinion(s) of the author(s) only, not the American Chemical Society, ILPI, Safety Emporium, or any other party. Use of any information on this page is at the reader's own risk. Unauthorized reproduction of these materials is prohibited. Send questions/comments about the archive to
The maintenance and hosting of the DCHAS-L archive is provided through the generous support of Safety Emporium.