From: Rita Kay Calhoun <r.calhoun**At_Symbol_Here**MOREHEADSTATE.EDU>
Subject: Re: [DCHAS-L] Stirrer Hot Plates
Date: March 28, 2013 9:51:24 AM EDT
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: <225837173.451981.1364414181561.JavaMail.root**At_Symbol_Here**>

Exactly, Donald.  Also, in order to actually be explosion-proof the HP/S has to be hard-wired into the power outlet.  Do those of you who say it is forbidden to use regular HP/S's actually have your explosion-proof ones hard-wired in?   In industry where you might do the same process day after day it would make sense to have a permanent station set up.  In academia where you do different reactions every week and have 20 + students it would be untenable.   Besides, don't they cost ~ 3-4K a piece? 



Kay Calhoun


From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU]On Behalf Of Don Abramowitz
Sent: Wednesday, March 27, 2013 3:56 PM
Subject: Re: [DCHAS-L] Stirrer Hot Plates


For what it's worth, my understanding is most hot plate/magnetic stirrers in common use in organic chemistry labs are not explosion proof/approved for hazardous locations.   They are potential ignition sources when used with flammable solvents, but when operated in properly functioning fume hoods, the solvent vapors are swept away at a sufficient rate such that the ignition sources don't typically  encounter vapor concentrations in the flammable (> LEL) range.   I'm not saying that's a good policy, but I believe it is why (along with the use of reflux condensers)  there isn't an epidemic of fires when flammable liquids are used with these devices. 

Donald Abramowitz
Environmental Health & Safety Officer
Bryn Mawr College
Bryn Mawr, PA


What is your policy on heating or mixing flammable liquids with non-explosion proof, not spark proof stirrer hot plates?


Tom Bialke, MSPH, CIH

Mgr. Research Safety and Compliance

Kent State University

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