Date: Wed, 27 Apr 2011 19:21:54 -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: ILPI <info**At_Symbol_Here**ILPI.COM>
Subject: Re: Safe Procedure?
In-Reply-To: <DD8008707CBF0242AA5A659D39AD73E609E75E608D**At_Symbol_Here**NDMSSCC02.ndc.nasa.gov>

Under normal circumstances, the reaction works as planned, the formic acid condenses, and essentially no fumes are released.  And if something goes wrong, the fume hood will be the Last Line of Defense.

In the case you presented, the Last Line of Defense has been taken out, and the researcher has made attempts to reduce the probability of Something Unexpected happening.  Essentially, he's trying to revise the procedure so that the fume hood is not needed.

Unfortunately, one can not anticipate all possible Something Unexpected scenarios and the researcher has only taken steps to avert one obvious failure scenario - runaway heating.   He/she has not planned for cooling water failure.   So if the water fails, all of the formic acid goes out into the lab.  Which won't hurt anyone right away as the lab will be empty, but will corrode all sorts of things and no doubt work its way into other occupied spaces and have numerous unintended consequences.

On the other hand, if the condenser water outlet had a flow indicator that would cut power to the heater in the event of cooling water failure, then perhaps the risk becomes acceptable.   A sensor that will switch off the heater and fire off a solenoid to shut the water supply (in the event of a popped hose, for example) is about $800 and the solenoid is about $170 based on the price sheet I have for the models we are will be selling in the near future.

Or maybe not, because something *else* Unexpected could also happen.  Ah, the joy of risk assessment!

Rob Toreki

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On Apr 27, 2011, at 4:33 PM, Cody, Regina J. (GSFC-6910) wrote:

My colleague is seeking advice as to whether the following procedure was a safe way to deal with a fume hood failure.
Here is his description of what occurred.  I have a picture (96 kb) of the initial setup if needed and the list server can handle.
A 48 hour reflux to extract 19 g of powdered rocky material in 68 g of 95% formic acid was needed.    A 250 mL single neck (14/20 joint) round bottom flask on an electric heating mantle with a Liebig Condenser in a fume hood.  When heat was applied, a glass beaker was inverted and placed over the top of the condenser to prevent any particulates from contaminating the system (without risking a pressurization).  One day into the extraction the building fume hood fans stopped.  The lab manager decided that terminating the procedure would compromise the rare meteorite sample and elected to proceed as follows.  He added a second identical water cooled Liebig Condenser above the first, closed the hood sash, and evacuated the 17,600 ft^3 lab (with proper warning signs on all the doors) until the completion of the experiment on the following day. 
 
Was this an unsafe action?
Thank you for your comments.
Regina Cody
*************************
Regina Cody
NASA Goddard Space Flight Center
Code 691
Greenbelt, MD 20771
Office: 301-286-3782
Fax: 301-286-1683

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Fax: (856) 553-6154, PO Box 1003, Blackwood, NJ 08012

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