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
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
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