[labnetwork] silane in gas cabinet

Tom Britton tbritton at criticalsystemsinc.com
Fri Jun 28 12:48:07 EDT 2013

Hello Shawn,

The short answer is yes, you can connect the cabinet exhaust from two gases to the general exhaust. The long answer is as follows:

The two gases in the same cabinet, as you have noted, isn't correct. 2% silane is right on the edge of being classified either as a flammable (1.39% to <2%) or a pyrophoric (2% to 30%). Your ammonia is classified as a Toxic/Corrosive. It also has Flammable characteristics. These can share a general exhaust but should never share a common exhaust from the same cabinet, a common panel, purge or venturi as the potential for cross contamination is very real here. Whether you choose to classify your silane as a pyrophoric or a flammable in this case is up to your safety department. Since 2% is right on the edge, you most likely would not violate the UFC by classifying this as a flammable, but you do need to separate the two cylinders.

Most companies put their silane gases in a separate bunker than the other gases. This is how you said you did it at your previous company, which was correct. Having silane separate, with the gas systems complying to CGA Code G-13, would give you the pneumatic cylinder valve, the high flow door (if the cylinder is inside a gas cabinet), the UVIR, regulator bonnets kits and the restricted flow orifice in the cylinder. We can help size the RFO if you would like.

If you need pricing on the cabinets, please let me know.

Good luck with your project sir.

Tom Britton
Director of Sales
Critical Systems, Inc.
7000 W. Victory Road
Boise, ID 83709
Direct: 208-890-1417
Shop:   877-572-5515

    "World Leader in UHP Reconditioned
 Gas Delivery & Abatement Technologies"

From: labnetwork-bounces at mtl.mit.edu [mailto:labnetwork-bounces at mtl.mit.edu] On Behalf Of Shawn Wagoner
Sent: Thursday, June 27, 2013 12:40 PM
To: labnetwork at mtl.mit.edu
Subject: [labnetwork] silane in gas cabinet

                Here in my lab we have a PECVD system that uses 2%silane in argon.  The cylinder is in a cabinet in the service chase.  The silane shares this cabinet with a bottle of ammonia.  The cabinet is connected to the general exhaust that is used throughout the lab.  I don't really like the setup but this is how the system was running when I was hired and came to the university.  This setup is different from my industrial experience where the silane was outdoors in a bunker.

The lab will be moving to a larger cleanroom space.   While I will not have an outdoor bunker at the new facility, I will take this opportunity to improve the situation.   I intend to purchase a new cabinet for the 2%silane that will allow me to use a cylinder with a pneumatic valve, DISS fitting and a dedicated purge cylinder.  This is more in line with my prior experience.    Are there any concerns or issues with connecting the cabinet to the common exhaust?  Again this new lab only has general exhaust that runs throughout the entire lab.

Shawn Wagoner

Shawn Wagoner
Nanofabrication Laboratory at Binghamton University

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