Well, if the studies on the carbon filters are advancing, let's think about where this research needs to go.
1. ACTUAL WEIGHT/KG DATA. There needs to actual data on all the various volatiles that you will generate in that hood. Activated carbon cannot collect all types of
inorganic and organic gases and vapors at the same efficiency. And with the literally millions of possible volatiles that can be created in a fume hood, we have no way of knowing which will be effectively captured and which will not. The only data
I have seen is the weight/kg collection of certain common hydrocarbon solvents and even these varied.
2. CHEMICALS THAT ARE POORLY ADSORBED OR WHICH DAMAGE CARBON FILTERS. We need to consider in particular those chemicals which are KNOWN to either be poorly collected or which affect activated carbon's adsorbtion potential. Some of these are identified
by the makers of carbon filters for respirators as those which are poorly captured or those which shorten service life. Included are acetaldehyde, butane, butylamine, butyraldehyde, carbon monoxide, chlorobromomethane, 1-chloro-1,1-difluoroethane, 2-chloro-1,3-butadine,
chlorodifluoromethane, chloropentafluoroethane, (and most other chloro, fluoro and bromo-aliphatics), cyanogen, cyanogen chloride, cyclopentane, decaborane, diazomethane, diborane, dimethyl ether, 1,1-dimethylhydrazine, enflurane, ethylamine, ethyl bromide,
ethyl chloride, ethyl ether, glyoxal, hexafluoroacetone, isobutyraldehyde, ketene, methyl acetylene, methyl alcohol, methyl bromide, methyl formate, methyl iodide, methyl mercaptan, nitric acid, nitric oxide, nitrous oxide, propane, propionaldehyde, vinyl
bromide, vinyl chloride, vinyl fluoride, vinylidene fluoride, -- AND -- the products of combustion from ANY common hydrocarbon from paper, to oil, to cigarettes, and so on. These smokes they will contain thousands of chemicals and tars which will affect
3. MIXTURES OF CHEMICALS. Data from more than one chemical at a time may be needed.
4. CHEMICALS WHICH GREATLY SHORTEN SERVICE LIFE. There must be some kind of clear prohibition for use with any substance known to damage activated charcoal such as oil mists or water mist/steam.
5. END OF SERVICE LIFE INDICATORS are a joke when you consider all the different chemicals that could be generated in a fume hood both on purpose and accidentally. Is this ESLI even going to detect all the stuff above? Impossible. Even plain old nitric
acid may be an issue. And they can't detect inorganic particulates. Again, ESLI are probably best at detecting hydrocarbon solvents--and not all of them either.
I spent a considerable amount of time a few years ago talking with activated charcoal primary mfgs about data. My conclusion is that the problem is too big and too extensive to cover all the bases, My recommendations are that the ductless hoods can be
used with a HEPA filter for small generation of inorganic particulates or organic dusts that are not reactive or highly hazardous. They must not be used for nanoparticles about which we also do not have good data except for carbon nanotubes.
If someone wants to install carbon filter ductless hoods in a teaching lab in which all of the experiments and the chemicals they will use are known and there is certified lab-generated collection data from the filter manufacturer on the chemicals (or close
analogs) they will use, I won't have a fit, but my report will also include a long list of precautions along with this use. And I expect labs to post these precautions near the hood so no one will be confused about the limitations.
Now, I may sound unreasonable (I usually do), but if any filter maker out there wants to send me certified lab data to the contrary, my address and e-mail are below. I will be the first to jump on board and recommend your product. It would be a joy not
to have to find a chase to run the exhaust ducts to the roof on every planning job.
Monona Rossol, M.S., M.F.A., Industrial Hygienist
President: Arts, Crafts & Theater Safety, Inc.
Safety Officer: Local USA829, IATSE
181 Thompson St., #23
New York, NY 10012 212-777-0062
From: Rindoks, Kurt <KurtRindoks**At_Symbol_Here**KEWAUNEE.COM
To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Sent: Fri, Mar 21, 2014 5:49 am
Subject: Re: [DCHAS-L] NFPA 45 -- 2015
These studies are ten years old and the ductless hood technology has advance considerably since then. You should look at the SEFA 9 - 2010 standard which discusses the Recommended Practices
for Ductless Enclosures. The DH III type hood did not exist when the NIAD and OSHA studies were conducted. These types of hoods offer solutions to some of the issues sited. SEFA 9 also requires that an Application Questionnaire be submitted to the manufacturer
to help you find the correct solution for your application. A ductless hood may or may not be appropriate for your application and the cost may or may not prove beneficial for you. A ductless enclosure or a ductless hood is not a direct substitute for a
fume hood because a fume hood allows for a broader application. More often now, people are becoming more energy efficient and a ductless hood may be one way to save some of the energy used in a laboratory. Before you make a decision, you need to be certain
that a ductless hood is safe and efficient for your application.
Vice President Engineering and Product Development
Kewaunee Scientific Corp
I have a question regarding NFPA 45. I am wondering how undergraduate research labs fit into the definition of Instructional laboratory
units. As defined in the 2011 version of NFPA:
"used for education past the 12th grade and before post-college
graduate-level instruction for the purposes
of instruction of six or more persons for four or more hours per day or more than 12 hours per week. Experiments and tests conducted in instructional lab units are under
the direct supervision of an instructor. Lab units used for graduate or post-graduate research are
not to be considered instructional lab units."
The definition specifically excludes graduate and post-graduate research. Why doesn't
it exclude "undergrad research" too? This would be situations where the instructor is not always present, but labs where several undergraduate students are working at the same time.
Charlotte J. Head, P.E.
industrial environmental consultant
North Kingstown, RI 02852
Dan referenced NFPA 45 in his recent email.
I would like to mention that NFPA 45: Standard on Fire Protection for Laboratories Using Chemicals (current edition: 2011) is in the process of revision. The next edition is scheduled for 2015.
(I am a member of the 45 Technical Committee.)
Barbara L. Foster
Director of Laboratory Safety
Eberly College of Arts and Sciences
West Virginia University
Look at this NIH policy document on ductless hoods. It is from 2005. That is where I got the NFPA reference for NFPA 45. It is section 6.4.1.
I was asked by my department to assist in deciding whether to purchase ductless fumehoods for our undergraduate chemistry labs. We are planning to use these for flammable solvents, and reactions involving HCl and NaOH. These hoods will be used by undergraduates
for research also. Any input on the safety issues involved with these equipments versus the regular hoods would be appreciated.
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