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. 

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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