Note a conflicting procedure / documentation in the procedures folder: 9.8.3 Pumping/Venting Procedure . These are being reconciled.
Readiness checklist
- All chamber doors must be closed
- All chamber flanges must be in place (no obvious opening)
- TC1:VGC:11, TC1:VGC:12, TC1-VGC-01, TC1-VGC-02, TC1-VGC-03, TC1-VGC-04 must be closed
- MEZ-PMF-01 EBARA A70, MEZ-PMF-02 EBARA A70 must be off (if faulted, press RESET)
- TC1-VGC-04, MEZ:VGC:17, MEZ:VGC:18, MEZ-VIC-19 must be closed
- MEZ-GPI-02 must display ~ 6.5e+02 torr (if lower, open MEZ:VGC:18 until restored, then close)
- TC1-VGC-04, MEZ:VGC:17, MEZ:VGC:18, MEZ-VIC-19 must be closed and allowed to open
- The gas ballast control knob of the scroll pump should be set to level 0
- Turbo pump should be at "Full Speed" (if not follow Turbo pump startup procedurebelow)
Pumpdown procedure
- Press OPN on TC1-VGC-04
- Press RUN on MEZ-PMF-01 EBARA A70
- Press OPN on MEZ:VGC:17 (wait a few seconds if MEZ:VGC:17 cannot open)
- Press RUN on MEZ-PMF-02 EBARA A70
- Press OPN on MEZ-VIC-19 (wait a few seconds if MEZ-VIC-19 cannot open)
- Wait until MEC:TC1:GPI:01 drops below 5.0e-02 torr
- Press OPN on TC1-VGC-02
- Press CLS on MEZ:VGC:17
- Press STP on MEZ-PMF-01 EBARA A70
- Press CLS on MEZ-VIC-19
- Press STP on MEZ-PMF-02 EBARA A70
- Press OPN on MEZ:VGC:18
- Wait until MEZ-GPI-02 passes above ~ 6.5e+02 torr
- Press CLS on MEZ:VGC:18
If something goes off track during this procedure, initiate the venting procedure and check for leaks (flanges, virtual leaks, waterlines, etc).
Turbo pump startup
- Open mechome, go to the tab "User Devices", open the panel "User Sentry PDU"
- Turn On "Roughing pump PTM 02 (turbo 2)"
- Wait until SEW:GPI:04 drops below 1.0e-02 torr
- Press OPN on SEW-VGC-15
- Press RUN next to the turbo pump logo
- Wait until turbo pump displays "Full Speed"
Version tracking
| Version | Release date | Description |
|---|---|---|
| v1.00 |
| Demonstration version |
| v1.01 |
| Simplification of the procedure using only checklists |
Overview of the pumping system
Default setup of the pumping system
MEC's pumping system is comprised of 2 multi-stage dry vacuum pumps (Ebara A70) located on the mezzanine above the hutch, and 2 turbo pumps (Varian TV-2KG) backed with a scroll pump (Edwards xds35i). The following sketch shows the vacuum system as displayed in the controls window.
The dark grey rectangle in the center symbolizes the target chamber and displays the readout values of different vacuum gauges measuring the in-chamber pressure (top: cold-cathode, bottom-left: pirani, right: capacitance). Let's note that the capacitance gauge is out of order and displays incorrect values.
The top right side of the window details the primary pump subsystem. The ends of this branch lead to the 2 Ebara pumps. Controllable gate-valves are positioned at the target chamber entrance to isolate the primary pump subsystem, at the inlet of each independent Ebara pump, and along the line to allow for venting of the subsystem. Pirani gauges are also used to monitor the pressure along the subsystem pumping line and at the inlet of both Ebara pumps.
The bottom side of the window details the secondary pump subsystem. It comprises 3 branches: 2 of them are identical and symmetric on the sketch, and 1 of them (left-most), the shortest one with only 3 symbols in a straight one, is obsolete. The 2 indentical branches each contain a Varian turbo pump and a scroll pump. The chamber is isolated from these subsystems by a gate-valve, a second gate-valve is used to isolate the turbo from the scroll when the system is shut down. A pirani gauge monitors the quality of the backup pressure provided by the scroll pump.
Finally, the top left side of the windows helps control the venting valves. There are 2 independent venting valves: one supplies compressed dry air (CDA) to initiate the venting procedure, the second one simply opens the chamber to the ambiant atmospheric air (Atm).
Current modifications in the pumping system
MEC has recently experienced a turbo pump failure. As a consequence, we are operating the pumping system with the following structural modifications. The primary vacuum subsystem and the venting valves are unchanged. The modifications are at the bottom side of the window with the failed turbo pump in a "Disabled" status and a backup turbo pump (Maglev) positioned in the formerly obsolete left-most branch.
The target chamber is in a secondary vacuum state on this sketch. The primary subsystem is vented and the maglev (gate-valve TC1-VGC-01 open/green) is pumping the chamber which reached 2.10-4 torr on the cold-cathode gauge (the pirani gauge reached its lower readout limit). The Varian turbo branch (gate-valve TC1-VGC-02 closed/red) is not activated yet, but the turbo is accelerating after startup as shown by the yellow circle.
The procedure presented on this page will explain how to operate the primary vacuum subsystem and a branch of the secondary vacuum subsystem when running with a Varian turbo pump. The Maglev pump is a temporary solution for experiments needing high-quality vacuum, most of our beamtimes run with only one Varian.
Nomenclature of the vacuum system components
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Multi-stage dry pump (pre-pump)
RUN and STP buttons are used
to operate the pump
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Gate-valve
state: closed, not allowed to open
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Pressure gauge
state: reading
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Gate-valve
state: closed, allowed to open
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Pressure gauge
state: out of range
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Turbo pump
state: off
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Gate-valve
state: open, allowed to open
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Pressure interlock display
red: condition not met
green: condition met
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Turbo pump
state: accelerating
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Cold-cathode status display
circle: status display
ENA and DIS buttons are used
to force start or stop the gauge
Tools necessary to the pumping procedure
Primary vacuum
Secondary vacuum
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