How to vent a vacuum chamber

  • get a liquid nitrogen dewar, there are some in the LKW schleuse.

  • connect the copper coil to the dewar. The copper coil should be connected to a pump cart when not in use elsewhere, so that we can find it easily.

    ../_images/cu-coil.jpg

  • open the dewar

  • connect the venting manifold to the venting valve of the chamber to be vented, or to the pump cart as shown:

    ../_images/pump-cart.jpg

    in case you are venting through a turbo pump, there is an adaptor to 8 mm plastic tube as shown below in the video.

  • the venting manifold has a regulator, a relief valve and a pressure gauge connected. Open the regulator such that the pressure in the manifold is just above ambient pressure. In this case, the relief valve makes a buzzing noise:

  • switch off all pumps and anything else that should not see air, like some pressure gauges

  • in case you are venting through a turbo pump, switch on the “vent enable”:

    • use the arrow keys on the pump controller to select option 12: “Vent enab”.
    • press both arrow keys at once to enable editing
    • use the arrows to select “on”
    • press both arrow keys again to confirm

  • all turbo pumps you are not venting through should have vent enable set to off!

  • if you’re not venting through a turbo pump, once all turbo pumps ran down to a point that they may be vented, open the venting valve

  • no matter how you vented, once the venting starts the buzzing of the relief valve should change. Once the chamber is up to ambient pressure, it should change again. To be sure, close regulator. The needle on the manifold’s pressure gauge should stand still while closing the regulator if the chamber is fully vented, if not it should move as nitrogen is still flowing into the chamber.

  • congratulations, your chamber is vented! Close the venting valve, or switch the vent enable to “off” again.