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--- vacuum_control [2016/11/10 23:12]
pereira [Venting analysis-line lower-dipole section]
+++ vacuum_control [2019/10/17 10:43] (current)
pereira [Object Box]
@@ Line 40: / Line 40: @@
 The ion gauge for the [[Stations|Object station chamber]] vacuum system makes too much light for the object scintillator.  This ion gauge **I188IG** should be left off except when actually monitoring the vacuum level.
 As stated above (see figure above), this ion-gauge can only be turned off "locally" by pressing the **EMIS** button on its controllers, which are located in the S3 vault on the middle level in the electronics racks under the stairs to the top level.
 ===== Target Chamber =====
@@ Line 46: / Line 48: @@
 **Important note**: Ensure that the experimenters never pump the chamber down if the spectrograph vacuum section is vented. The pressure gradient between both sections would "push" the structure of the spectrograph beam line towards the target chamber, potentially damaging the bellows of the line.
-==== Venting analysis-line lower-dipole section ====
-In order to ensure that the beamline in the target area is properly aligned with respect to the beam axis, it is necessary to install a telescope in between the last two quadrupoles of the analysis line, as well as a "cross hair" plate in between the last quadrupole and the target chamber. Although the alignment of the telescope is done by lab staff (e.g. Dave Sanderson), the user is responsible for removing the gate valve I246GV separating the analysis line and the target area. This of course, requires that the lower-dipole section is properly vented. The venting process is generally done by the device physicist, following the steps:
-  - Verify that the target area is vented.
-  - Using the EMIS controllers in the middle level of the S3 vault (see figure above), ensure that the ion gauge I225IG is turned off.
-  - Ensure that gate valves I246GV (between lower-dipole section and target area) and I215GV (between intermediate image area and the lower-dipole section) are closed.
-  - Open **S800vac** PanelMate.
-  - Go to page 4 ("lower beamline dipoles vacuum system, section 16")
-  - Window "VENT STATUS" should be green and display "GOOD VACUUM"
-  - Click on "VENT STATUS" and select "BEGIN VENTING PROCEDURE". The I225GV turbo gate valve will be automatically closed (see figure below). However, the venting process won't be complete until you open the manual valve.
-  - Walk to the bottom level of the S3 vault, right downstream of the last two dipoles of the analysis line. Locate the I226PG Pirani gauge and ensure that it reads rough-vacuum pressure (few militorr).
-  - Slowly open the manual valve (see picture below) and verify that the pressure read in I226PG raises slowly.
-  - After the section is vented (atmospheric pressure) close the manual gate valve.
-{{:wiki:panelmates800vac-ventinglowerdipoles.jpg?800|PanelMate s800va (page 4) displaying venting status of lower-dipole section}}
-{{:wiki:manualvalve-lowerdipoles.jpg?800|Manual venting valve of lower-dipole section}}
 ===== Spectrograph =====
 This system is pumped with cryopumps. Please do not vent this section if the target chamber is under vacuum pressure. The pressure gradient between both sections would "push" the structure of the spectrograph beam line towards the target chamber, potentially damaging the bellows of the line.

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