Thank you Colby Bellew
rcrane at snf.stanford.edu
Tue Feb 18 11:57:47 PST 2003
I would like to take a moment to thank Colby Bellew for an action taken
last week when he noticed a wbdiff hot pot that was in trouble and
notified staff member Jim Haydon. This is an excellent example of a
conscientious user and community spirit which is the heart of our fab
operations. Thank you, Colby Bellew.
The wbdiff hot pot in question had its fluid level lowered to the top of
the heater band. The low fluid level sensor failed. With the heater left
on, the sulfuric/peroxide mix was locally boiling and presented a
potential splash hazard and, ultimately, a potential fire hazard. Since
the temperature sensor was no long submerged, the heater controller was
applying full power. The fluid level sensor line (the N2 bubbler) had
condensed fluid in it which gave a false indication of a full pot. A
klixon over-temperature sensor switch would still have provided the
second level of fire protection. Level
sense lines have checked, cleared or replaced in wbdiff and wbsilicide.
Wbnonmetal and wbmetal are next in line for checking. Always disable the
bench when you are finished. If the next user already has an operation
in progress, have them enable over you.
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