[labnetwork] Question: use of gas alarm logic to prevent building evacuations on silane bottle changes...

[Bill Flounders]

 From UC Berkeley:

low level - email and txt alarm to staff
high level - seal gases, annunciate local alarm, evac lab
high level persistent (>60sec) - link to building fire alarm activated, 
annunciate
building fire alarm, evac entire building

Bill

Bill Flounders, Ph.D.
Executive Director
Berkeley Marvell Nanofabrication Laboratory
520 Sutardja Dai Hall  Mail Code 1754
Berkeley, CA  94720

Office:      510-809-8600
http://nanolab.berkeley.edu/




Ian Harvey wrote:
> Dear Labnetwork,
>
> *Question:*
> How to prevent spurious gas/silane alarms (e.g., from cylinder change 
> burps) from unnecessarily evacuating an entire building?
>
> *Background:*
> We recently had a very brief burst/decay of silane associated with the 
> removal of the dust cap in preparation for installing a new silane 
> cylinder. The burst was captured by our gas alarm as a single "spike" 
> that exceeded the level-2 alarm threshold (10 PPM) for 3 seconds and 
> decayed back to below level 1 (5 PPM) after 12 seconds (peak was 19 
> PPM).  However, the fire alarm was triggered, the entire engineering 
> building was evacuated for 20 minutes, and six fire trucks showed up.
>
> This cylinder was 13 months old, 1 month past its expiration date. 
>  The cylinder was chained and strapped into position inside the gas 
> cabinet when the dust cap was removed.  At present, we feel it is best 
> to evacuate the building, since our old lab is in a B-class occupancy 
> area.  However, in our new facility, our silane will be behind a 2 hr 
> firewall in a special gas room, attached to the single-story fab wing 
> and 50 yards from (but still attached to) the multi-story research 
> tower.  We are looking for more robust system-level solutions limiting 
> unnecessary evacuation of the research tower in our new facility.
>
> *Approaches:* Aside from procedural approaches like "Don't use expired 
> cylinders", and "Open dust caps very slowly", has anyone attempted to 
> use alarm logic in their HPM system, such as: "<<If>> the alarm 
> originates in the gas box <<and>> room air sensor is below 
> threshold...  or variations on timing between sense and decay to stage 
> the triggering of different alarm levels??
>
> How do others handle this situation in your respective labs?
>
> Thank you in advance for your inputs!
>
> --Ian
>
> ********************************************
> Ian R. Harvey, Ph.D.
> Associate Director, Utah nanofab
> College of Engineering / University of Utah
>
> Research Associate Professor
> Department of Mechanical Engineering
> Adjunct Associate Professor
> Department of Electrical & Computer Engineering
> 2232 MEB
>
> mail to suite 2110 MEB, 50 S. Central Campus Drive
> Salt Lake City, Utah   84112-9011
> 801/585-6162 (voicemail)
> 801/581-5676 (lab main number)
> www.nanofab.utah.edu <http://www.nanofab.utah.edu>
>
>
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