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In the case of pressure rise on gauges 3259 and 3291 due to a failure of one or more pumps in the DS-DPS system, this procedure should be used to isolate the beamline and stop the pressure from rising further.  See the attached document for the full procedure.

In most cases this will isolate the beamline and allow the other remaining operating stage to pump down the beamline and allow operations to commence.

Link to full procedure:   FACET S20 DPS Troubleshooting - 03-04-2022.pdf

Step-by-step troubleshooting guide

  1. Open the full schematic: Select “DPS full schematic…” from the LI20 Vacuum page on Epics.

  2. If the 3259:DS1 FV-DS1 foreline valve is closed AND the 3259:DS1 turbo is off, then this stage is in the normal “off” state – go to step 4.

  3. If the 3259:DS1 FV-DS1 foreline valve is open, and either the 3259 turbo or roughing pump (or both) are off, then this indicates a problem with this stage. The flow chart indicates the actions to be taken to put the stage into an “off” state:

    DS1 troubleshooting flow chart:


    If you get to the green “Everything looks good” box, then this stage appears to be in a good state.


  4. Now – assess the DS2 stage in the same way: If the 3291:DS2 FV-DS2 foreline valve is closed AND the 3291:DS2 turbo is off, then this stage is in the normal “off” state – go to step 6.

  5. If the 3291:DS2 FV-DS1 foreline valve is open, and either the 3291 turbo or roughing pump (or both) are off, then this indicates a problem with this stage. The flow chart indicates the actions to be taken to put the stage into an “off” state:

    DS2 troubleshooting flow chart:

  6. If at this point either of the 3259 or 3291 turbos are running, the beamline should be pumping down to <1e-6 Torr in a very short period of time. If neither is running, but the 3250 valve is open – then the beamline should be slowly being pumped down through the dump line turbo.

  7. If both turbos are off and the 3250 valve is closed, then this section of the beamline will not pump down until one of the pumps is restarted.


If you reach this state and cannot continue or experience any difficulties – please call Doug Storey at SLAC extension # 3020, or cell # 650-656-5940.



You MUST click on the “DPS full schematic…” button on the LI20 vacuum page in order to see the full schematic.



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