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Venting/pumping Object box

Vent Object chamber

From the S800 Main Vacuum page, go to the Object chamber page, opening the page shown in the figure below, and make sure of the following:

  • Before you start, make sure that the gate valves named D2341 BGV and D2303 BGV are closed and that the IG is off.
  • The vent valve should also be closed when you begin.
  • The valve to the turbo pump TVG should be closed. If the chamber will be vented for a long time, Valve FV should also be closed and the turbo pump should be switched off .

The procedure is then as follows:

  1. Close the valve to the roughing pump RV.
  2. Now you can plot the pressure vs time at BPG to monitor the pressure before you open the vent valve.
  3. Keep a constant eye on the pressure level as it increases rapidly. When it approaches 800 torr, it is imperative that you close the venting valve. Failure to do so will result in over-pressure in the chamber since it will continue to be filled with dry nitrogen.
  4. You can now enter and open the chamber.

Pumping Object chamber

From S800 Vacuum Main Page, go to Object chamber page. This will open the page in the figure below.

  • Make sure that the IG is off.
  • When you start, you should have RV closed, FV open and the TGV valve, Vent valve, as well as the gate valves named D2341 BGV and D2303 BGV all closed.
  • Close FV and open RV to start pumping down the object chamber with the roughing pump. You can make a plot of the pressure vs time at BPG at this point.
  • Section D2337 will initially be red with vacuum status: 'Bad vacuum'. This must turn to yellow with status 'Poor vacuum'. Wait for the pressure reading at BPG to drop to below 100 mTorr before you close RV and open FV.
  • Wait until the vacuum reading at FPG to drops to below 200 mTorr before you can safely turn on the turbo pump.
  • After turning on the turbo pump, wait for the inner circle of the pump symbol to turn green and the pump to reach 40 000 rpm before you open the valve at TGV.
  • When the pressure decreases to below 10-3 Torr, you should see the pressure bottom out on your BPG plot, you can turn on the IG and also plot its pressure over time. Section D2337 should turn green and the vacuum status should turn to 'Good vacuum'.

The object chamber vacuum control page

venting_pumping_object_box.txt · Last modified: 2023/06/02 17:14 by swartzj