Date: Thu, 22 Sep 2011 08:03:28 -0600
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: Bob Weeks <rweeks**At_Symbol_Here**LANL.GOV>
Subject: Re: Fume Hoods
In-Reply-To: <CAAgNRJhbE7Dq9FAEOBQ44fGjCY3nTat02QwEOee1ZBY1Tc6Qcg**At_Symbol_Here**>

I see that H2S is one of the compounds considered for use here. Please remember that hydrogen sulfide is detected by the nose and then suddenly there is no smell. One might suspect that the gas has dissipated when in actuality the olfactory nerves have become fatigued and are no longer responsive. The IDLH for hydrogen sulfide is only 100 ppm so permanent damage or death could conceivably occur w/i 30 minutes at these concentrations. I am aware of one instance here in NM in which an oil field worker stuck his head in an oil field settling tank and died instantly. It has been reported that one breath at 700 ppm is fatal.

Bob Weeks, PhD, CIH

From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**] On Behalf Of Janet Baum
Sent: Wednesday, September 21, 2011 12:24 PM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: Re: [DCHAS-L] Fume Hoods

Dear Michael, Do you mean ductless fume hoods, i.e. recirculating air fume hoods? There's a huge difference in the IH capabilities between "ductless" and "ducted" fume hoods, if both are installed correctly. There are many IH risks and QA/QC considerations in using ductless hoods. Do you have documented and compelling reasons to consider using ductless hoods?

Janet Baum, DivCHAS

On Wed, Sep 21, 2011 at 10:07 AM, Michael Hojjatie <mhojjatie**At_Symbol_Here**> wrote:

Dear colleagues:



We are in the process of building a new Laboratory and contemplating between using Dustless Fume Hoods vs. Ducted Exhaust Hoods. We will be using a variety of hazardous chemicals including carbon disulfide, acetonitrile, toluene, benzene, some carcinogenic suspect chemicals, hydrogen sulfide and sulfur dioxide gases.


I appreciate sharing your experiences with ductless fume hoods and whether you recommend these type of hoods for hazardous chemical work using the aforementioned chemical examples as well as advantages and disadvantages of these hoods vs. the ducted exhaust hoods (safety concerns, costs, maintenance, etc.)






Michael Hojjatie, Ph.D.

R&D director, TKI


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