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--- venting_pumping_intermediate_image_box [2017/06/12 14:25]
pereira [Venting/pumping Intermediate Image box and filling PPACs with gas]
+++ venting_pumping_intermediate_image_box [2018/12/19 11:01]
pereira [Venting/pumping Intermediate Image box and filling PPACs with gas]
@@ Line 1: / Line 1: @@
-===== Venting/pumping Intermediate Image box and filling PPACs with gas =====
+====== Venting/pumping Intermediate Image box and filling PPACs with gas ======
-The procedures to vent/pump the S800 Intermediate Image box, and/or filling the PPAC detectors with gas must be done carefully to ensure that the PPACs are not damaged. For instance, before venting the chamber, we have to make sure that the PPACs are empty and equalized with respect to the vacuum in the chamber. In order to avoid errors, an automated gas handling system (II-GHS) was designed to perform these tasks safety. The system is schematically illustrated in the figure below. It shows the status of the valves (red: closed, white: open) when the intermediate image chamber is under vacuum and the PPACs are filled with gas:
+===== General information =====
+The procedures to vent/pump the S800 Intermediate Image box, and/or filling the PPAC detectors with gas must be done carefully to ensure that the PPACs are not damaged. For instance, before venting the chamber, we have to make sure that the PPACs are empty and equalized with respect to the vacuum in the chamber. In order to avoid errors, an automated gas handling system (II-GHS) was designed to perform these tasks safely. The system is schematically illustrated in the figure below. It shows the status of the valves (red: closed, white: open) when the intermediate image chamber is under vacuum and the PPACs are filled with gas (NOTE: This figure was taken from the A1900 GHS included in Barney. A similar GUI for the S800 II PPACs is not yet available):
 {{:wiki:ghsiippacs.png?1000|Gas Handling System of S800 Intermediate Image}}
-The II-GHS equipment (valves, flow-meter, pipes, etc.) are located on the west balcony of the top level in the S3 vault (see figure below):
+The II-GHS equipment (valves, flow-meter, pipes, isobutane gas bottle. etc.) are located on the west balcony of the top level in the S3 vault (see figure below):
+{{:wiki:IIGHShardware.jpg?600|Gas Handling System of S800 Intermediate Image}}
+===== Vent Intermediate-image chamber =====
+Requirements: PanelMate files **S3_Gas_Handling** and **S800Vac**
+  * Verify that PPACs are in automatic mode with gas removed (**S3_Gas_Handling**)
+        *  The "GH System Status box should read "Auto Mode Gas Removed"
+        * If gas is removed but the system is not in the automatic mode, consult the Beam Physicists or Device Physicist. NOTE: the only valves that should be open in **S3_Gas_Handling** are the "Det Bypass" and "Chmbr Bypass
+  * Verify that PPACs are not biased:
+        * Check that the detectors are unbiased by opening the [[HV bias|HV GUI]]
+        * Notify the system of the bias-off state by selecting the "I214BON_CONFIRM" box in **S3_Gas_Handling** and clicking "PP BIAS OFF CONFIRMED"
+  * Open **S800Vac** and go to page 03 ("Intermediate image box vacuum system sec 15")
+  * Isolate chamber by closing gate valves **I212GV** and **I215GV**
+  * [[Vacuum control|Turn off]] ion gauge **I213IG**
+  * Check box "PUMPDOWN STATUS INTERMEDIATE IMAGE BOX". It should read "Good vacuum"
+{{:wiki:iis800vac_pumped.jpg?500|S800vac Panel Mate}}.
+  * In order to begin venting process, select box "VENT STATUS" and click "BEGIN VENTING PROCEDURE"
+        * Box "VENT STATUS" should change from "VENT PROCEDURE STOPPED" to "WAITING FOR VENT TIMER".
+        * Turbo gate valve **I214GV** will be automatically closed and pressure in chamber will start rising (as seen in **I215PG**) {{:wiki:iis800vac_startventing.jpg?500|S800vac Panel Mate: start venting}}.
+        * When **I215PG** reads atmospheric pressure, select the box "VENT STATUS" and click "STOP VENTING PROCESS". {{:wiki:iis800vac_stopventing.jpg?500|S800vac Panel Mate: stop venting}}.
+        * The status in the box "VENT STATUS" should change from "WAITING FOR VENT TIMER" to "VENT PROCEDURE STOPPED"
+        * You can now open the chamber
+===== Pumping Intermediate-image chamber =====
+Requirements: PanelMate files **S3_Gas_Handling** and **S800Vac**
+  * Verify that Chamber is closed and pressure-relief valve (north side of the chamber) is properly closed (NOTE: sometimes, due to overpressure from dry N2 during the venting procedure, the O-ring in pressure-relief valve flange is moved out of place)
+  * Verify that PPACs are not biased by opening the [[HV bias|HV GUI]]
+  * IMPORTANT: Verify that manual roughing pump valve located near the intermediate-image chamber is closed{{:wiki:manualvalverough.jpg?350|Manual valve rough pump}}.
-{{:wiki:IIGHShardware.jpg?1000|Gas Handling System of S800 Intermediate Image}}
+  * Insert PPACs/turn on light (Diagnostic Drives PanelMate) and verify condition through sight window on south side of the chamber (be careful no to bump the bullet camera).
-==== Vent focal-plane chamber ====
+  * Open **S800Vac** and go to page 03 ("Intermediate image box vacuum system sec 15")
-  * Open the [[hv_bias|HV Remote Control]] GUI and ensure that the focal-plane detectors are unbiased
+  * Check "PUMPDOWN STATUS INTERMEDIATE IMAGE BOX"; it should read "PUMPDOWN STOPPED". Select that box and click on "START PUMPDOWN". The chamber will not be pumped yet because the manual roughing pump valve is closed.
-  * Open the [[gas_handling_system#labview_control_program|Labview gas handling system]] and verify that there is no gas in the CRDCs and IC. Open valves **4** (IC supply), **5** (IC bypass), **6** (IC focal-plane bypass), **20** (CRDC supply), **21** (CRDC bypass), and **22** (CRDC focal-plane bypass). The rest of the valves should be closed
+  * Slowly crack manual roughing valve
-  * Ensure that the manual venting valve located on the south side of the chamber is closed (see figures below)  {{:wiki:fp-venting-valve-Daniel.jpg?350|FP chamber manual venting valve}} {{:wiki:fp-venting-valve.jpg?350|FP chamber manual venting valve}}
+        * Start slow (< 1 Torr/sec). Chamber pressure is displayed in **I215PG** in **S800Vac** PanelMate. There is also a local display of the mechanical pump pressure on a Granville-Phillips 275 Mini-Convectron, which is helpful to control rate of pumping.
-  * Ensure that the FP ion gauge (I264IG) is off (see details [[vacuum_control|here]])
+        * Verify PPACs changing shape through sighting window.
-  * Open PanelMate and select **S800vac** file in directory \\exp\files\control\ncsdata\General\Qt\Templates. Go to page 07, click on the **VENT STATUS** window and begin the venting procedure. The **VENT VALVE I260VV** window will turn red and display "OPEN". The pressure should remain constant because the manual venting valve is still closed
+        * Pump to about 100 Torr before fully opening the roughing valve.
-  * Gently open the manual venting valve until the pressure displayed in the Pirani Gauge (see figure below) increases by ~1 torr every 15 seconds (see figures below)
+  * Once roughing valve is fully open, retract PPACs and turn lights off.
-{{:wiki:fp-pirani.jpg?350|FP chamber manual venting valve}}
+  * When the pressure in **I215PG** is below 200 mTorr, the Turbo Pump will start automatically through the following sequence:
-  * Wait until the chamber is vented (few hours). The **I261PG** Pirani Gauge should read slightly above atmospheric pressure (due to the dry N2 flow pumped to the chamber). The window **VENT STATUS** in PanelMate should display "VENT VALVE OPEN". The window **PUMPDOWN STATUS** should display "PUMPDOWN STOPPED"
+        * **I214RV** will be closed
+        * **I214FV** will be opened
+        * **I214GV** will be opened
+  * When the pressure ready by **I215PG** is few mTorr, you can turn on the ion gauge **I213IG**. Good vacuum will take ~1-2 hours.
+  * NOTE: it sometimes happens that the foreline pressure rises above the trip point for the Turbo Pump (e.g. if the pumpdown timer expires before pressure is below 300 mTorr, or there is too much back-up pressure from the chamber when the foreline valve opens). In this situation, you will see that: (1) the turbo pump will stop, (2) the turbo gate valve **I214GV** will be closed, (3) the foreline valve **I214FV** will be closed and the corresponding PanelMate box will turn red and display an error message "Foreline pressure > 2 Torr", and (4) the foreline pressure will be few Torr. In a situation like this, foreline valve needs to be bypassed open (in PanelMate) and the TP needs to be restarted:
+          * Select box labeled "FORELINE VLVE I214FV" and the click on "BYBASS VAC INTERLOCKS OPEN" button
+          * Select box labeled "TURBO PUMP INTERMEDIATE IMAGE BOX I214TP" and  click "START"
+          * Turbo pump will start ramping speed. When the TP reaches 40000 RPM, the **I214GV** will open automatically.
+          * When foreline vacuum gets below 2 Torr, you can select "FORELINE VLVE I214FV" and click "REMOVE BYPASS"
+          * (Note: sometimes it is necessary to repeat this operation a couple of times).
+  * At the end of the procedure, close the manual roughing pump valve

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