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Message ID: 14074     Entry time: Mon Jul 16 18:12:00 2018
Author: Koji 
Type: Update 
Category: VAC 
Subject: Adding a manual gate valve between TP1 and V1/VM2 

[Steve Koji]

We are in the process of adding a manual gate valve between TP1 (Osaka Maglev) and the other gate valves (I suppose V1 and VM2).
The work is still on going and we will continue to work on this tomorrow. Because this section is isolated from the main volume, this work does not hold off the possible rough pumping tomorrow morning.

The motivation of this work is as follows:
- Since TP2 failed, the main vacuum volume has been pumped down by TP1 and TP3. However TP3 is not capable to handle the large pressure difference at the early stage of the turbo pumping. This cause TP3 to have excessive heating or even thermal shutdown.
- The remedy is to put a gate valve between TPs and the main vacuum to limit the amount of gas flowing into the TPs. This indeed slows down the pumping speed of turbo, but this is not the dominant part of the pumping time.

Actual work:
- Comfirmed TP1 is isolated.
- Unscrewed the flange of TP1.
- Remove TP1. This required to lift up TP1 with some shim as the nuts interferes with the TP1 body. (Attachment1, 2, 3)
- Now remove 10inch flange adapter. (Attachment4)
Attach 10"-8" adapter and 8" rotational sleeve. (Attachment5)

Attachment 1: P_20180716_155413.jpg  3.222 MB  | Hide | Hide all
Attachment 2: P_20180716_155645.jpg  2.830 MB  | Hide | Hide all
Attachment 3: P_20180716_155738.jpg  3.005 MB  | Hide | Hide all
Attachment 4: P_20180716_162307.jpg  2.983 MB  | Hide | Hide all
Attachment 5: P_20180716_172000.jpg  3.491 MB  | Hide | Hide all
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