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Previous by Date: Subject: Re: Flammable gas in a quartz tube/electric furnace assembly Date: Wed, 20 Jan 2010 09:18:20 -0500 Author: Joseph Passante |
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Look at NFPA 86 for guidance - Standard for Ovens and Furnaces -----Original Message----- From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**LIST.UVM.EDU] On Behalf Of Dan Crowl Sent: Tuesday, January 19, 2010 6:12 PM To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU Subject: Re: [DCHAS-L] Flammable gas in a quartz tube/electric furnace assembly I assume that there is no air or oxygen in the gas streams? Otherwise the gases will self-ignite. You will need to have a system to insure that no air or oxygen is present in the streams under all conditions. On-line gas analysis might be necessary. What procedure will you use to remove the air initially from the tubes? How will you know it is gone? Also, if the gas leaks out it will mix with air and spontaneously ignite since it is above the ait. Where do the gases come from, how are the gases mixed and where do they go? I would recommend a complete hazards analysis of the entire system, including the location, in order to do this properly. The operational details are just as important as the design. The hazards analysis would need to be reviewed by a team of safety experts. This would require a lot of documentation and complete flow diagrams of the process and specifications for all equipment. The days of going into a lab and incrementally building a lab experiment are gone. Dan Crowl Michigan Tech University On 1/19/2010 6:16 PM, Alfred Bouziane wrote: > Hello everyone: > > A researcher here plans to continuously flow 100 % flammable gas > (methane, ethylene, hydrogen, or mixture) at 1 cfm through a quartz > tube/electric furnace assembly that is heated to 800 degrees C (exceeds > the auto-ignition temperature of the gases). The researcher intends to > have four (4) of these units (~18"h x 24"d x 60" w) in the lab; at least > two units will be active throughout the day. > > The discussion centers on where to safely set up and operate them. The > researcher proposed mounting the units on open benchtops (two per > benchtop) to accommodate their size and facilitate use (the gases would > be piped to the units via stainless steel tubing from an adjacent gas > room). Though seemingly practical, I feel this would require > considerable $$ investment in engineering controls (canopy hood, blast > shields, etc.) to adequately protect the research staff from potential > mishaps (gas leaks, explosions). My thought is to mount the assembly in > the lab's wet process hood (vertical laminar flow) and lower the sash > during operation. Though not ideal, it would reduce the potential of > these mishaps. NOTE: There are only two available process hoods in the > lab, hence, only two assemblies would be up and running (not a bad thing > in my opinion). > > Here are my questions: > > 1. Has anyone tackled a problem like this in the past? How was it resolved? > > 2. What other safeguards do you recommend? > > I welcome your collective input. Thank you in advance for your help. > > Best regards, > > Alfred M. Bouziane > > Project Manager > > Environmental Health and Safety > > University of Southern California > > http://capsnet.usc.edu/EHS/index.cfm >
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