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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: 12487     Entry time: Tue Sep 13 16:16:28 2016     Reply to this: 12488
Author: Chris 
Type: Omnistructure 
Category: VAC 
Subject: vacuum interlock bypassed 

(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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