From: Yamaira Gonzalez <gonzalyi**At_Symbol_Here**YAHOO.COM>
Subject: Re: [DCHAS-L] Stirrer Hot Plates
Date: March 27, 2013 5:38:31 PM EDT
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: <225837173.451981.1364414181561.JavaMail.root**At_Symbol_Here**>

In my experience, we have used them for flammables as long as the equipment is inside a N2 or inert atmosphere.  Keep in mind fire is a chemical reaction called oxidation. It involves four key elements: fuel, heat, oxygen, and the chemical reaction between them.  Each of the 4 elements is essential. If anyone of the elements is removed, the possibility of fire is eliminated.  Inerting is normally only considered when the flammable or explosive hazard cannot be eliminated by other means i.e. substitution of flammable material with non-flammable, equipment selection,  adjustment of process conditions to ensure substances are below flammable limits.
Yamy Gonzalez
Process Engineer

From: Don Abramowitz <dabramow**At_Symbol_Here**BRYNMAWR.EDU>
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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