Toxic gas alarm

Dick Crane rcrane at snf.stanford.edu
Thu Jan 31 18:59:49 PST 2002


Dear building occupants, 

Around 4:07 PM this afternoon, the SNF lab experienced a toxic gas alarm
causing an evacuation of the fab. It was caused by three problems: first
the gas detection device (MDA) had been serviced early this week and the
gas detector for the ion implanter was adjusted to six times the normal
sensitivity. Second, a lecture bottle of 15% PH3 had just been changed
and was undergoing a standard 24 hour leak check having passed the first
two leak checks. The bottle fitting had a small leak in the parts per
billion range. The gas system lives in a safety vented enclosure. The
hyper-sensitive detector alarmed. Third, a monitoring computer error
prevented a rapid identification of the problem.

Since the gas was contained and was never in the room air, no alarms
were given for CIS and CISX spaces other than the fab.

I would like to review the standard evacuation procedures. 

1.  Fire horns and clear strobe lights mean fire or other
danger...evacuate the building, proceed to the assembly area between
HEPL and Ginzton.
2.  Blue strobes and horns in the fab mean possible toxic gas leak in a
contained area...evacuate the fab and wait in the lobby.
3.  Blue strobes and horns in and outside the building mean possible
toxic gas present in the room air in the fab or other lab in
CISX...evacuate the building and proceed to the assembly area between
HEPL and Ginzton.

Sorry for the inconvenience,

Dick Crane



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