Date: Wed, 20 Jan 2010 00:14:04 -0800
Reply-To: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
Sender: DCHAS-L Discussion List <DCHAS-L**At_Symbol_Here**LIST.UVM.EDU>
From: Jean & Ken Smith <smith.j.k**At_Symbol_Here**SBCGLOBAL.NET>
Subject: Re: Flammable gas in a quartz tube/electric furnace assembly
In-Reply-To: <8EDCBF65F98F1C40BCC235C034B3ED3704D7A1BA7C**At_Symbol_Here**capsm01.CAPSD.USC.EDU>

It sounds like a problem in the making.  Dealing with those gases at those temperatures is, in my opinion, a ticking time bomb.  Has anyone thought about using a flame shield in the pipes to stop a flame front from penetrating the supply pipes?  I agree with the previous writers that purging the oxygen in the piping will be a problem.  Leaking pipes, especially hydrogen which will find the tiniest hole or just penetrate the walls anyhow, pose a real problem.


Using equipment of that size in any hood will cause disruption of the airflow pattern inside and potentially cause pockets of sluggish or no flow areas with possible buildup of concentrations of flammable/explosive mixtures.  That will pose a hazard to the researcher or others because there would be no warnings.


Ken Smith

Retired CIH


-----Original Message-----
From: DCHAS-L Discussion List [mailto:DCHAS-L**At_Symbol_Here**] On Behalf Of Alfred Bouziane
Sent: Tuesday, January 19, 2010 3:16 PM
To: DCHAS-L**At_Symbol_Here**LIST.UVM.EDU
Subject: [DCHAS-L] Flammable gas in a quartz tube/electric furnace assembly


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.

                     ;                         & nbsp;                 

Best regards,


Alfred M. Bouziane

Project Manager

Environmental Health and Safety

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