The CF (ConFlat) flange is the most widely used for high vacuum and UHV applications.
Many gauges, instruments, accessories and feedthroughs are available on this flange system.
The seal mechanism is a knife-edge that is machined below the flange's flat surface. As the bolts of a flange-pair are tightened, the knife-edges make annular grooves on each side of a soft metal gasket. The extruded metal fills all the machining marks and surface defects in the flange, yielding a leak-tight seal. The CF seal operates from 760 torr (103 mbar) to < 1 x 10-13 Torr (< 1.3 x 10-13 mbar), and within the temperature range -196° C to 450° C (depending on material). Flange sizes in North America are normally referenced by their outside diameter (O.D.). However, in Europe and much of Asia, the nominal internal diameter (nominal I.D.) of the largest tube that can be welded to a bored flange is usually referenced in their nomenclature.
Lightweight and non-magnetic for applications sensitive to magnetic materials
Good thermal conductivity
Lower residual radioactivity than flanges manufactured from ferrous materials
General properties of aluminum and the surface preparation of these flanges yield low outgassing rates
Knife-edges of flanges coated with CrN for added hardness
CrN coating maximum temperature on the knife edges is 150°C
Aluminum flanges require the use of aluminum gaskets
All dimensions listed in the table below, unless otherwise stated, are in inches.
All dimensions listed in the table below, unless otherwise stated, are in millimeters.