Description of CF Components

The generation of ultra high vacuum (UHV) makes great demands on the material and connections. Therefore the CF standard was created in the UHV technology (ISO 3669; enhancement ISO/TS 3669-2).

CF flanges are manufactured from circular blanks of stainless steel on CNC machines. Rotatable flanges are bipartite and consist of an inner part with the seal face and an outer part with the bolt holes. CF flanges have an annular groove on the vacuum side for the reception of the gasket and a knife-edge. Sealing is achieved by means of a flat gasket of oxygen-free (OFHC) copper because of the low leak rate and high bakeout temperature necessary for UHV technology. This gasket can be used generally only once due to the plastic deformation by the knife-edge. Fastening is achieved by bolts which must be tightened uniformly crosswise in order to avoid any kind of distortion. Such flange connections have a leak rate of < 1.0E-11 mbar l/s and are bakeable up to 450 °C.