Date: Wed, 20 Jan 2010 10:34:25 -0500
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: Pierre Chantal <Pierre.Chantal**At_Symbol_Here**HC-SC.GC.CA>
Subject: Re: Flammable gas in a quartz tube/electric furnace assembly
In-Reply-To: <110994D9-9C1C-4296-997F-26C2C28F749E**At_Symbol_Here**>

I have operated a similar plant ( a little smaller 18" h x 12" od) with 
quartz tube at these temperatures with a flow of a few liters per minute. 
We did have modified slightly the furnace to allow a slow purge of 
nitrogen within the furnace (i.e. a small hole in the insulation to allow 
a 1/8" ss tubing. We have operated this furnace uniterrupted for up to 500 
h and have never experience any problem. The units where installed in a 
pilot plant area under a canopy.

Hope this help


Joseph Passante  
Sent by: DCHAS-L Discussion List 
2010-01-20 09:18 AM
Please respond to
DCHAS-L Discussion List 


Re: [DCHAS-L] Flammable gas in a quartz tube/electric furnace assembly

What the original poster describes is very common.  Nanotube are made this 
way (lab scale)  and furnaces used to pacify surfaces (such as silicon 
wafers) in fabrication labs.  The only difference is the flow volumes.  Is 
it CFM or scfm?  I've never seen flow rates in excess of a 100 cc/min.

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 labŐs 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).
Joseph R. Passante, CIH, CHO
Associate Director
Chemical Hygiene Officer
Environmental Health & Radiation Safety
University of Pennsylvania

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