Date: Tue, 6 Jul 2010 14:37:28 -0700
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: Michael Hurwitz <Tesla**At_Symbol_Here**LMI.NET>
Subject: Re: Sol-gel drying process
In-Reply-To: <33EBEF33F9721740B892CD7909B06EC3135248BA23**At_Symbol_Here**>

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Propylene Glycol is flammable with a flash point around 100C.=A0 I’ve seen laboratory fires (no explosions thankfully) happen during a scale-up of high flash point flammable process, DMSO in my cause (boy did that stink).=A0 In the small scale there’s not enough vapor that can collect and ignite.=A0 Putting a flammable solvent in an oven above its flashpoint can easily cause explosions. =A0=A0I can’t tell from the description as to whether the oven itself had a vent.


Michael D. Hurwitz

Renegade Chemistry Consulting

Cell: 650.804.8036


Freelance Chemistry on Demand

From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**] On Behalf Of Perry Cooper
Sent: Tuesday, July 06, 2010 9:04 AM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: [DCHAS-L] Sol-gel drying process

Sharing an incident. Anyone want to chip in on recommendations? J

General lab exhaust through the fume hood. Some equipment exhausted with localized flex duct but not the oven.

Adjacent areas complained of strong alcohol odor.

“….. intent to prepare a batch of fine particulate size aluminum oxide via the sol gel process. The components were an organometallic (aluminum sec- butoxide), a solvent (2-propanol) and water.  1.5l of 2-propanol was placed in a porcelain-lined steel container. 4.5kg of aluminum sec-butoxide was added to the solvent while mixing. After these components were thoroughly mixed, 1.1l of water was added resulting in the formation of AlOH particles from the organic precursor.  At this point, the composition was a viscous slurry. In order to reduce the solvent content, the container was placed on a hot plate inside the fume hood. The composition was heated (temperature unknown but estimated to be 70-80=B0C) for approximately 4 hours.  At the end of this period, most of the solvent had evaporated, leaving a slightly moist “cake”. In order to remove the remaining solvent, the container was taken to room xxxxx and placed in a convection oven. I partially covered the container with a lid to allow venting and to prevent any swirling debris from contaminating the material. Oven temperature was set at 130=B0C and the general exhaust in this room was turned on. My intent was to let the material dry overnight and I left for the day. When I returned the following day, I checked the oven and it was apparent that there had been an accident at some point after I left.  I later learned that there had been a small explosion and fire. I believe the fire was confined to the oven and was extinguished by covering the container with the lid.  The oven door was bent when it swung open and contacted the control enclosure but no other damage is apparent. In the past, I have used these same procedures and equipment to make similar compositions without incident….”



_______________________________ Perry D. Cooper, MS, HEM, CCHO
Manager - HSE - JHU

The Johns Hopkins University
Health, Safety & Environment

Homewood Campus Safety Office
3400 N. Charles Street

G04 Wyman Park Bldg
Baltimore, MD 21218
Office: 410-516-2345
Fax: 410-516-4314

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