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venting_pumping_intermediate_image_box [2018/04/25 17:53]
pereira [Pumping Intermediate-image chamber] |
venting_pumping_intermediate_image_box [2023/02/13 10:44]
noji Updated descriptions about the II-GHS based upon "S800 Intermediate Image PPAC Gas Handling System Operation Manual" (v4) provided to us on 2/8/2023 by B. Ewert. |
| ====== 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 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): | * [[#General information]] |
| | * [[#Vent Intermediate-image chamber|Venting Intermediate-image chamber]] |
| | * [[#Pumping Intermediate-image chamber]] |
| | * [[#Filling/Removing gas in Intermediate-image delay PPAC]] |
| |
| {{:wiki:ghsiippacs.png?1000|Gas Handling System of S800 Intermediate Image}} | ===== 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 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): |
| 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}} | {{:wiki:IIGHShardware.jpg?600|Gas Handling System of S800 Intermediate Image}} |
| |
| | The GHS is operated remotely through CS studio. Its page can be found on the EXP network through FRIB EXP Main → S800 → GHS Pages (Secondary Pages) → Intermediate Image PPAC and is shown below. |
| |
| | {{:wiki:ii-ppac-ghs-css.png|}} |
| |
| | The layout of the II-GHS is shown below. |
| |
| | {{:wiki:ii-ppac-ghs-layout.png|}} |
| |
| | The operational states of the II-GHS are shown in the diagram below. |
| |
| | {{:wiki:ii-ppac-ghs-operationalstates.png|}} |
| |
| ===== Vent Intermediate-image chamber ===== | ===== Emptying Detectors ===== |
| Requirements: PanelMate files **S3_Gas_Handling** and **S800Vac** | - Set “PPAC Setpoint” to 0 Torr. |
| | - Click **EMPTY** on the “GHS_II-PPAC_Main” page to begin pumping out the gas quickly. |
| * Verify that PPACs are in automatic mode with gas removed (**S3_Gas_Handling**) | - When “PPAC Pressure” reads < 0.1 Torr, click **MAN** and then **AUTO**. This will release the remaining gas into the diagnostics box. |
| * The "GH System Status box should read "Auto Mode Gas Removed" | - Monitor D2340 pumping station and ensure the TMP stays on and TGV remains open. If not, contact the Vacuum Operation group. |
| * 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 | - Valves #1-5 should be closed and valve #6 should remain open. From this state click PUMP to enter pump mode and leave the system in this state until it is ready to be filled. |
| * Verify that PPACs are not biased: | * Jorge noted on 2/12/2023 that this step did not work; he reported that when he clicked **PUMP** nothing happened. Instead, he had to “manually” enter the PV name associated with this command and changed from 0 to 1. He speculated that this was most likely due to a CS Studio problem. |
| * 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" | |
| * Isolate chamber by closing gate valves **I212GV** and **I215GV** | |
| * [[Vacuum control|Turn off]] ion gauge **I213IG** | |
| * Open **S800Vac** and go to page 03 ("Intermediate image box vacuum system sec 15") | |
| * 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}}. | |
| |
| * 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). | ===== Filling and Running Detectors ===== |
| * Open **S800Vac** and go to page 03 ("Intermediate image box vacuum system sec 15") | - If in Vent Mode, click **PUMP** then click **RUN** to enter Run Mode. |
| * 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. | - If in Pump Mode, click **RUN** to enter Run Mode. |
| * Slowly crack manual roughing valve | - Plot and monitor IG_D2430:VP_RD while filling. Ion gauge reading will increase but should remain <1E-5 Torr when PPACs are running at full pressure. |
| * 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. | - Step up “PPAC Setpoint” by 1 Torr from 0 to 6 Torr. Allow the “PPAC Pressure” to stabilize for 15 seconds at each step. This should be a quick process but **DO NOT** simply set the “PPAC Setpoint” to 6 Torr as the gas flow could overwhelm the system. |
| * Verify PPACs changing shape through sighting window. | - PPAC pressure should stabilize after ~1 min. HV may now be turned on to operate the PPACs. |
| * Pump to about 100 Torr before fully opening the roughing valve. | |
| * 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: | |
| * **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 **I214GV** 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. When the TP is at speed (40000 RPM) the **I214GV** will open automatically (Note: sometimes it is necessary to repeat this operation a couple of times). When the TP is running fine and the system is stable (pressure in **I326PG** ~ mTorr), you can remove the bypass of the foreline valve | |
| * At the end of the procedure, close the manual roughing pump valve | |
| |
| | ===== Troubleshooting ===== |
| | - If any issues are encountered during filling, running, or emptying, contact the Vacuum Operation group for assistance. |
