CF Flanges for High Vacuum and Ultra-High Vacuum (UHV)
CF flanges provide all metal sealing for vacuum chamber systems. CF (ConFlat) flanges use an OFHC copper gasket and knife-edge flange, whicxh is a bolted flange. The knife edge of the flange presses into the softer copper gasket to make a high vacuum seal. CF is perfect for high vacuum, ultra-high vacuum (UHV) and where high temperature in needed. Deformation of the metal gasket fills small defects in the flange, allowing ConFlat flanges to operate down to 10−13 Torr (10−11 Pa) pressure. Bake-out of the flange can be up to 450 deg C.
The construction of CF Flanges can be specified with tapped or untapped holes. CF Flanges can be either rotatable or non-rotatable to allow for variations in vacuum systems. Untapped flanges can be connected to each other with stainless steel bolts and hex nuts or plate nuts.
CF Vacuum Fittings
CF Vacuum Fittings (ConFlat) are used in high vacuum and ultra-high (UHV) applications. CF vacuum hardware is preferred in these applications due to its low outgassing and superior vacuum sealing capability. CF vacuum connections are most often all metal seals usually including copper gasket material. These seals are can be heated to 400C to bake-out and minimize out-gassing.
How CF Seals Work
CF seals normally operate with the principal of a knife edge seal. The flange edge is formed as it is tightened, resulting in an indention in the softer gasket material, usually copper. This knife edge is able to seal the vacuum system from atmosphere. Sizing of CF vacuum flanges is from 1.33" to 16" OD. Bolts either tapped to untapped are used as the seal force mechanism.
Materials of Construction
CF Fittings are usually constructed with 304 stainless steel. Upon request, 316L SS can be provided. Gasket material is often high purity, oxygen-free (OFHC) copper. Vito gaskets can be provided for applications where ultra-high vacuum is not needed. One advantage of CF fittings is that they can be baked to 400C.
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CF Blank Flanges