As a number of you are aware shortly after midnight on Monday night
(technically at about 00:13 Tuesday morning) there was a blue toxic gas
alarm that rang and evacuated the lab. This was triggered by the
detector that monitors POCl3 and BBr3 in the Tylan bank that contains
tylan5 and tylan6 .... although, I believe that the problem had nothing
to do with the tubes in that bank.
At about 00:30 I received an automated call from the toxic gas
monitoring system and at about 00:40 received a call from Stanford work
control. I arrived at the lab at about 1 a.m. After studying the alarm
history and looking at detected levels .... which had returned to zero
about 10 minutes after the initial alarm ... I entered the lab with all
of our hand-held monitoring instruments. At that point, I was unable to
detect any levels of any toxic gases.
I did, however, find that the vacuum pump for tylannitride had ruptured
the pump casing and blew pump oil outside the cabinet. It is likely
that this hot pump oil ... that contains residuals of dichlorosilane and
hydrogen chloride ... was the source of the chemical that triggered the
POCl3/BBr3 sensor in the adjacent Tylan bank.
Interestingly, there was no record of tylannitride running anything
other than the PUMP10 program at this time. It is highly unusual for a
pump to have ruptured in this way when it was under vacuum with nothing
but a bit of nitrogen flowing.
While tylannitride is down until further notice pending pump replacement
and thorough testing of all elements in the system, everything else in
the lab should be ready for normal service. I have done my best to mop
up and dispose of the pump oil outside of the tylannitride cabinet and
have blanked off the exhaust from that pump that leads to the burn box
so that there will be no unwanted leak of room air into the burnbox system.
If anyone smelled anything unusual during this incident or has any
relevant information, please contact me.
At this point, aside from tylannitride, the lab is operational and
available for use.
Thank you for your continued support,
John
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