aLIGO LHO Logbook

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chandra.romel@LIGO.ORG - posted 19:50, Tuesday 09 May 2017 - last comment - 22:07, Tuesday 09 May 2017(36114)

Vacuum summary (vertex vent)

IP6 is actually powered ON even though it appears red on MEDM. It's currently on the new style power supply.
John and I experimented with x-beam manifold pressure by toggling valves on main turbo and IP6.
Left the x-beam manifold turbo pump ON but valved out of main volume - will resume leak checking tomorrow while we pump down vertex.
Will start pump down Wed. morning. Left purge air ON overnight with flow into volume at one vent valve and the KF cap off of the other vent valve to dry out the volume.
Doors were off for 9 hours today.

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kyle.ryan@LIGO.ORG - 22:07, Tuesday 09 May 2017 (36115)

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I double checked the mechanical pressure gauges downstream of the 1.5 psi pressure regulator this morning after we noticed a high purge pressure value for the Vertex.  The flow demand was high at this time as BSC3's door was off (HAM4 door too?) and these gauges were showing about 1/2 psig which is as expected for this flow demand.  We resolved to adjust the "ATM" trim pot on PT120 before pumping tomorrow.  

I now am wondering if the pointers of these low pressure mechanical gauges were rotated past 360 degrees - indicating 1/2 psig but actually being 1/2 psig past n(360)?  We need to close off the purge air supply and allow the Vertex to "blow down" and equalize to room pressure tomorrow to see what PT120A reads in orderto see what is going on.