aLIGO LHO Logbook

LHO VE

kyle.ryan@LIGO.ORG - posted 16:51, Tuesday 24 February 2015 - last comment - 10:14, Wednesday 25 February 2015(16901)

Pumped HAM1 to rough vacuum (4 hours pumping = 0.3 torr at pump inlet, HAM1 pressure???)

Kyle, Gerardo 

Added remaining bolts to HAM1 West door and finished torquing -> Soft-closed GV5 and GV7 (GV5 hard-closed on its own at only 20 psi) -> Pumped HAM1 with scroll pump via vent/purge valve (as such, atmospheric pressure remains on air-side of closed vent/purge valve) -> Opened GV5 and GV7 

Richard M. is investigating getting signal cables to HAM1 gauges

Comments related to this report

kyle.ryan@LIGO.ORG - 10:14, Wednesday 25 February 2015 (16910)

Link

Kyle, Gerardo

~0910 hrs. local, Wednesday morning -> Installed temporary pirani gauge controller on top of HAM1 so as to view pressure until CDS cabling gets installed -> HAM1 now showing 0.4 torr which is as expected.

In retrospect, I should have not pumped HAM1 without this to monitor -> I had reasoned that the view ports are exposed to 2 atmospheres (gauge) differential (both directions) during bench testing so are considered "safe" -> I now consider the failure mode whereby a view port could have cracked during pumping resulting in a measurable change in the pump down curve -> In this scenario we would not have opened GV5 and GV7 -> Lesson learned