[labnetwork] Cl2, BCl3 and Silane sensors for toxic gas monitoring

[Dan P. Woodie]

Aju,

The standard within Cornell Engineering is that anywhere hazardous gases (flammable or toxic) are used, we monitor both the exhausted enclosure (gas cabinet, tool cabinet, etc.) and the breathing zone (ambient) air with separate sensors. The exhausted sensors only shut off the gas while the ambient sensors will trigger an evacuation (local or floor) and notification to our Cornell emergency response team. If use locations (gas cabinet and tool using gas) are close enough, we will combine ambient detection or ducted detection (monitor both a gas cabinet and an adjacent gas distribution box with a single sensor where exhaust ducts combine). So, a gas cabinet piping a hazardous gas to an enclosed tool in another room will have four sensors (at a minimum): ambient by the tool, ambient by the gas cabinet, exhaust duct of tool enclosure, exhaust duct of gas cabinet. We got to this standard 20 years ago when we did peer surveys of other research institutions and their standards.

If you only measure the ambient, you are oblivious to gas leaks from your cylinders into your ductwork until you notice it, or someone opens the gas cabinet and gets exposed. Ambient measurements are to prove you meet OSHA requirements for personnel exposure. Each serves a separate purpose and regulatory requirement. Your local Authority Having Jurisdiction (AHJ) may only require one in the cabinet, but OSHA, NFPA, and other guidance codes that are brought in under Best Known Practice requirements will push for ambient detection along these lines.

Feel free to give me a reach out if you want to discuss more.

Dan

Daniel Woodie
Safety Manager / Facilities Engineer
College of Engineering
Cornell University
202 Ward Center
Ithaca, NY 14853
(607)254-4891
(607)227-2993 - cell

From: labnetwork <labnetwork-bounces at mtl.mit.edu> On Behalf Of Aju Jugessur
Sent: Friday, January 13, 2023 12:48 PM
To: Fab Network <labnetwork at mtl.mit.edu>
Subject: [labnetwork] Cl2, BCl3 and Silane sensors for toxic gas monitoring

Hi all,

We have ICP etcher and PECVD that use toxic gases such as Cl2, BCl3 and Silane. The exhausts from the pumps are connected to a scrubber and ph neutralization/acid waste system.

I am reaching out to get some advice on the specific locations of the Honeywell Midas sensors that we use, to detect any gas leak at the etchers and toxic gas monitoring system. We have sensors at the gas cabinets and ambient sensors at the tools.
However, there seems to be a disagreement between our design team and our EHS unit. The design team recommends having the sensors in the gas pods, where the leaks are most likely to occur. EHS would like to have the ambient sensors at the tools, in the breathing zone areas. As per local code requirements, sensors in the gas pods satisfies the safety requirements.

I would like to know what your set-up of the sensor locations for similar instruments is that you may have in your facility.
Any insights based on experience will be super helpful.

Thanks so much,
Aju


Aju Jugessur Ph.D. IEEE Sr. Member
Director, Colorado Shared Instrumentation
in Nanofabrication and Characterization (COSINC) Facility
Member of Inclusive Culture Council (ICC)
University of Colorado Boulder | College of Engineering & Applied Science
4001 Discovery Drive, N360G SEEC | Boulder, CO 80303| P: 303.735.5019
E-mail: aju.jugessur at colorado.edu<mailto:aju.jugessur at colorado.edu>
Personal Zoom link: https://cuboulder.zoom.us/my/ajugessur
www.colorado.edu/facility/cosinc<http://www.colorado.edu/facility/cosinc>
(MBA candidate, CU, Class of 2023)

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