venting_pumping_intermediate_image_box
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venting_pumping_intermediate_image_box [2017/06/13 15:40] pereira [Pumping Intermediate-image chamber] |
venting_pumping_intermediate_image_box [2018/08/14 10:52] pereira [Pumping Intermediate-image chamber] |
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| ====== Venting/ | ====== Venting/ | ||
| - | 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: | + | 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): |
| {{: | {{: | ||
| - | 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, |
| {{: | {{: | ||
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| * Check box " | * Check box " | ||
| {{: | {{: | ||
| - | * In order to begin venting process, select | + | * In order to begin venting process, select box "VENT STATUS" |
| * Box "VENT STATUS" | * Box "VENT STATUS" | ||
| * Turbo gate valve **I214GV** will be automatically closed and pressure in chamber will start rising (as seen in **I215PG**) {{: | * Turbo gate valve **I214GV** will be automatically closed and pressure in chamber will start rising (as seen in **I215PG**) {{: | ||
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| * 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 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]] | * Verify that PPACs are not biased by opening the [[HV bias|HV GUI]] | ||
| - | * IMPORTANT: | + | * IMPORTANT: |
| * 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). | * 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). | ||
| * Open **S800Vac** and go to page 03 (" | * Open **S800Vac** and go to page 03 (" | ||
| - | * Check " | + | * Check " |
| * Slowly crack manual roughing valve | * Slowly crack manual roughing valve | ||
| - | * Start slow (< 1 Torr/ | + | * Start slow (< 1 Torr/ |
| - | * Verify PPACs changing shape through sighting window | + | * Verify PPACs changing shape through sighting window. |
| - | * When PPACs equalize, increase | + | * Pump to about 100 Torr before fully opening the roughing valve. |
| * Once roughing valve is fully open, retract PPACs and turn lights off. | * Once roughing valve is fully open, retract PPACs and turn lights off. | ||
| * When the pressure in **I215PG** is below 200 mTorr, the Turbo Pump will start automatically through the following sequence: | * When the pressure in **I215PG** is below 200 mTorr, the Turbo Pump will start automatically through the following sequence: | ||
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| * **I214GV** 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. | * 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: WHAT TO DO IF PUMPDOWN TIMER EXPIRES BEFORE | + | * 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 " |
| + | * Select box labeled " | ||
| + | * Select box labeled "TURBO PUMP INTERMEDIATE IMAGE BOX I214TP" | ||
| + | * 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 " | ||
| + | * (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 | * At the end of the procedure, close the manual roughing pump valve | ||
venting_pumping_intermediate_image_box.txt · Last modified: 2024/01/12 09:37 by noji
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