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Reports until 08:37, Friday 14 January 2011
H2 General
robert.schofield@LIGO.ORG - posted 08:37, Friday 14 January 2011 (478)
Vacuum cleaning does not increase particle counts in nearby clean room
Ten minute cleaning sessions, using the black disc vacuum cleaner, produced zero dust counts just inside the curtains of a clean room over BSC7, a few meters from the cleaning site. The dust level was about the same for a session with just the vacuum on but no movements.

Mike L. asked me to try the vacuum test at night while it wouldn’t be confused by other activity in the LVEA. Patrick and I set up dust monitors and selected to clean in the hard-to-reach area along the output beam tube around HAM4 & 5. This region was near to the clean room over BSC7, which was open (with dust covers).  

No one was in the LVEA except me for the course of the experiment. For each cleaning session I entered, walked quickly to the cleaning area, turned on the Euroclean GD-930-H labeled “HEPA” (one of the black “disc” vacuum cleaners), with the long brush attachment, and cleaned for 10 minutes, running the attachment along the floor under the cable trays, behind the ISCT4 enclosure, and along the tops of the HAM4&5 chambers, where I could reach. After 10 minutes I turned off the vacuum cleaner and quickly left the LVEA. 

The attached figure shows dust monitor data for two of these cleaning sessions (note the two dust events). For the first cleaning session, a monitor was located a couple of meters away from the BSC7 clean room curtains (RED trace). The count level reached several hundred particles (0.3 microns or greater) per cubic foot during cleaning. For the second session, this monitor was moved just inside the curtains, on the ground. At its inside location, it recorded 0 counts during the second session. Thus the monitor was working, and dust levels were appreciable outside the clean room, but zero just inside, even though it was on the floor below the bottom of the curtains. The black trace is for the monitor a few meters from where I was cleaning. The blue trace is for a dust monitor on the far side of the BSC7 clean room, in the beer garden. The green trace is for the monitor at the halfway point of the 2k input mode cleaner. 

The monitor in the clean room around HAM12 did not detect my dust either.

Finally, I tried one session where I did no cleaning, I just turned the vacuum cleaner on and let it sit in one place. The counts at all locations were similar to when I was cleaning, so either most of the particles comes out of the vacuum cleaner, or else the air blowing out the exhaust stirs up most of the particles.

Robert, Patrick

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