Someone may need to review the NFPA standard. When I was with OSHA, I investigated an oven that exploded that was used with methanol (vitamin factory). Turns out they were using a Class A when they should have had the Class B. NFPA 86: Standard for Ovens and Furnaces Current Edition: 2007 Next Revision Cycle: Annual 2010 Document Scope: 1.1* Scope. 1.1.1 This standard applies to Class A, Class B, Class C, and Class D ovens, dryers, and furnaces, thermal oxidizers, and any other heated enclosure used for processing of materials and related equipment. 1.1.1.1 The terms ovens, dryers, and furnaces are used interchangeably and also apply to other heated enclosures used for processing of materials. 1.1.2* Within the scope of this standard, a Class A, Class B, or Class C oven is any heated enclosure operating at approximately atmospheric pressure and used for commercial and industrial processing of materials. 1.1.3 A Class A oven can utilize a low-oxygen atmosphere. 1.1.4 This standard applies to bakery ovens and Class A ovens, in all respects, and where reference is made to ANSI Z50.1, Bakery Equipment Ñ Safety Requirements, those requirements shall apply to bakery oven construction and safety. 1.1.5 This standard applies to atmosphere generators and atmosphere supply systems serving Class C furnaces and to furnaces with integral quench tanks or molten salt baths. 1.1.6* This standard applies to Class D ovens and furnaces operating above ambient temperatures to over 5000¡F (2760¡C) and at pressures normally below atmospheric to 10?8 torr (1.33 * 10?6 Pa). 1.1.7 This standard does not apply to the following: (1) Coal or other solid fuel-firing systems (2) Listed equipment with a heating system(s) that supplies a total input not exceeding 150,000 Btu/hr (44 kW) Kim Auletta Lab Safety Specialist EH&S Z=6200 Stony Brook University kauletta**At_Symbol_Here**notes.cc.sunysb.edu 631-632-3032 EH&S Web site: http://www.stonybrook.edu/ehs/lab/ Remember to wash your hands! From: List ModeratorTo: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU Date: 10/24/2009 08:44 AM Subject: Re: [DCHAS-L] Lab Incident: Lab explosion in Montana Sent by: DCHAS-L Discussion List From: Lucy Dillman Subject: Re: [DCHAS-L] 2 RE: [DCHAS-L] Lab Incident: Lab explosion in Montana Date: October 23, 2009 8:32:49 PM EDT When I was in college we had an oven blow up in a biochemistry teaching lab. We were doing an amino acid preparation from some source, I don't recall what, but it called for doing an ether/water layer, discarding the ether and then heating the water fraction. Apparently someone discarded the water and put the ether fraction in the oven. This was the day before Thanksgiving vacation. I don't know why it didn't flame out or blow up right away, but no one was in the lab when it went. There was damage to the oven, and glass flew all over the place, all the preps were lost. It was a good lesson in rechecking the procedure and not being in a rush to get out the door for vacation. Lucy Dillman
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