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Entry  Tue Sep 13 16:16:28 2016, Chris, Omnistructure, VAC, vacuum interlock bypassed 
    Reply  Tue Sep 13 17:47:04 2016, Steve, Update, VAC, pumpdown 79 completed 
       Reply  Wed Sep 14 09:44:09 2016, Steve, Update, VAC, pumpdown 79 completed pd79.pngpd79d2.jpgCCcg.jpg
          Reply  Thu Sep 15 10:36:32 2016, Steve, Update, VAC, pumpdown 79 day 3 vent78for73d.png
Message ID: 12488     Entry time: Tue Sep 13 17:47:04 2016     In reply to: 12487     Reply to this: 12492
Author: Steve 
Type: Update 
Category: VAC 
Subject: pumpdown 79 completed 

P1 IFO pressure is 1 mTorr, valve configuration: vacuum normal, annulosses are pumped, RGA is off, not pumped.

THANKS to Chris !

The shutters can be opened with high power.

No communication error message still exist.

I will reboot c1vac1 and c1vac2 to get gauge communication with medm tomorrow.



(Steve, Chris)

The pumpdown had stalled because of some ancient vacuum interlock code that prevented opening the valve V1 between the turbo pump and the main volume.

This interlock [0] compares the channels C1:Vac-P1_pressure and C1:Vac-PTP1_pressure, neither of which is functioning at the moment. The P1 channel apparently stopped reading sometime during the vent, and contained a value of ~700 torr, while the PTP1 channel contained 0. So the interlock code saw this huge apparent pressure difference and refused to move the valve.

To bypass this check, we used caput to enter a pressure of 0 for P1.

[0] /cvs/cds/caltech/state/from_luna/VacInterlock.st


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