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Message ID: 15668     Entry time: Tue Nov 10 11:59:37 2020
Author: gautam 
Type: Update 
Category: VAC 
Subject: Stuck RV2 

I've uploaded some more photos here. I believe the problem is a worn out thread where the main rotary handle attaches to the shaft that operates the valve.

This morning, I changed the valve config such that TP2 backs TP1 and that combo continues to pump on the main volume through the partially open RV2. TP3 was reconfigured to pump the annuli - initially, I backed it with the AUX drypump but since the load has decreased now, I am turning the AUX drypump off. At some point, if we want to try it, we can try pumping the main volume via the RGA line using TP2/TP3 and see if that allows us to get to a lower pressure, but for now, I think this is a suitable configuration to continue the IFO work.

There was a suggestion at the meeting that the saturation of the main volume pressure at 1mtorr could be due to a leak - to test, I closed V1 for ~5 hours and saw the pressure increased by 1.5 mtorr, which is in line with our estimates from the past. So I think we can discount that possibility.

Attachment 1: damagedThread.001.jpeg  1.180 MB  | Hide | Hide all
damagedThread.001.jpeg
Attachment 2: IFOstatus.png  41 kB  Uploaded Tue Nov 10 14:40:28 2020  | Hide | Hide all
IFOstatus.png
Attachment 3: P1a_leakTest.png  54 kB  Uploaded Thu Nov 12 15:29:06 2020  | Hide | Hide all
P1a_leakTest.png
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