From: Harry Elston <helston**At_Symbol_Here**MIDWESTCHEMSAFETY.COM>
Subject: Re: [DCHAS-L] high temp furnaces
Date: Mon, 25 Apr 2016 12:43:32 -0500
Reply-To: DCHAS-L <DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU>
Message-ID: 003c01d19f1a$035f5340$0a1df9c0$**At_Symbol_Here**



I’ve used muffle furnaces for two purposes for a couple of decades:  Ashing organics out of samples and performing salt fusions for analysis.


Ashing is performed in a low oxygen environment and is done relatively slowly over the course of 12-36 hours.  The door must be kept shut during the initial phases of the ashing to prevent deflagration.  A rapid introduction of oxygen at temperatures exceeding about 200-250 C can cause a deflagration.  Under no circumstances should the door be opened during the ashing process to “check on it.”  No, No, No.  Put a sign on the door saying “DON’T OPEN THIS.”    Most modern furnaces (for at least 25+ years) have the ability to ramp the temperatures up and down. and have overtemp shut offs on them.  NB:  These furnaces are not “sealed’ and do allow a limited amount of air into them during the process.  It’s a “low oxygen” environment, not a “no oxygen” environment.  Operation for ashing is usually an unattended operation after working hours; unless the lab director ignores the sign on the furnace door and opens it up.  Then it’s attended by the fire department among others.


Salt fusions are a completely attended operation as you have to do sample manipulations during the fusion process.




From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**] On Behalf Of Dodge, Janice
Sent: Monday, April 25, 2016 11:48 AM
Subject: [DCHAS-L] high temp furnaces


I am trying to find out how other universities are handling the use of unattended high temperature furnaces that may need to run overnight or even up to several weeks.  In particular, I am interested in requirements for when these operations must be monitored continuously, the use of over-temperature shut down devices, and requirements related to flow-through gases. 


Thanks for any guidance or policies you may wish to share.




Janice Dodge

Laboratory Safety Officer

Florida State University

(850) 644-8916


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