Honey, I Just Destroyed My Vacuum Seal

Christopher Lloyd as Doc Brown in Back to the Future (1985), © UNIVERSAL Pictures

If you need to connect two vacuum chambers, MPF offers flanges of various diameters with both fixed and rotatable bolt-holes. The most popular flange for achieving a high or ultra-high vacuum (UHV) is the Conflat® (CF) Flange, which creates a leak-tight seal with its machined knife-edge burrowing into each side of a soft metal gasket.

Flanges purchased from MPF always arrive clean and ready-for-use: we can either place your component in plastic clam shell or vacuum-pack it with desiccants. We also know, however, that our clients and customers are hands-on, DIY folks. Scientists experiment, and we encourage you to use our components in whatever way you chose.

In particular, some of our customers want to be sure that their components are clean, and may decide to bake them out before use. Usually this doesn’t result in any harm to the component, but when it comes to the Rotatable CF Flange—or any component with movable pieces—some caution is recommended.

During bakeout, if the rotatable flange is vertical (that is, if the flange “up in the air”) you risk crushing the ceramic seal beneath. When applying heat, the flange expands and can drop down, landing on the “I’m ready to bake out my flux capacitor” transition sleeve that holds the ceramic-to-metal seal. 

Subsequently cooling the component causes the CF flange to “shrink” back to its original size, thus crushing the joint and ceramic seal. In order to avoid this problem, the rotatable flange needs to remain on a flat surface so it does not move during bakeout. Fixed flanges, on the other hand, can be vertical and do not need to be placed on a flat surface while baking out your component. 

Rule of Thumb: If the component can move, make sure it’s not in a vertical position during bakeout.    

¹ MPF’s legal counsel wants it to be known that the flux capacitor is a fictitious instrument and that a DeLorean automobile cannot be outfitted to travel forward or backward in time