At 8:35 a PSL Dust Monitor went into a MAJOR dust alarm state for 0.3um particles. It generally stays around 0-300 counts, but at 8:35 it jumped up to 1000+ counts (see attached screen shot). Will notify Jason/Jeff B.
Klye was wet drilling in the west bay this morning between ~14:30 (07:30) and 15:15 (08:50).
Starting at 14:38 (07:38) the particle counts in the Bier Garten (LVEA10) spike up and drop back to normal by 17:00 (10:00).
Similar behavior is observed in HAM6 dust monitor (LVEA6). It starts to climb 14:48 (07:58) and drops off by 15:22 (08:22) - The HAM6 counts are elevated but only to 230 0.3um and 40 0.5um particles.
The dust monitor (PSL101) in the PSL Enclosure did not any counts for the 0.5um particles and no more than 20 of the 0.3um particles.
The Ante-Room-Room dust monitor (PSL102) spikes at 15:00 (08:00) however Ante-Room does not clear out like the rest of the monitored spaces in the LVEA. At the last check (17:50 (10:50)) the counts were 750 0.3um particles (alarm limit is 700 counts) and the 0.5 um counts are in the 200s.
See attached plot.
The PSL Ante-Room air is supplied by any overpressure from the LVEA and enters through vents in the bottom of the enclosure. The exhaust fans are not running during these times. Therefore there was no HEPA fan extraction of air from the Ante-Room and no corresponding air exchange. This is why the counts remained high in the PSL Ante-Room. Given the current design of the PSL Enclosure, if there are particles in the LVEA room air and the exhaust fans are on in the PSL Ante-Room these particles are going to be drawn into the PSL Anti-Room.
The 0.3um counts are still above the minor alarm level but getting better.
