CF Components

Functional principle CF1The 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/TS 3669-2:2007).

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.

Functional principle QCF2Sealing 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.

New and time-saving – the Quick CF Connection for HV to XHV

Quick CF (QCF) components and the appropriate clamp chains VaCFix® are developed by VACOM. They combine the sealing principle of ConFlat® flanges (knife-edge according to ISO / TS 3669-2) with the chain lock principle of KF connections.

QCF components can be assembled quick, easy and also space saving. They can be connected to all existing vacuum systems by adapters. The CF-QCF adapters offer the possibility to use the QCF connection on existing UHV vacuum systems and remain at all times flexible and supplier independent.

The demands of the UHV technology regarding a leak rate of <1.0E-11 mbar l/s and a bakeout temperature of the flange connection up to 350 °C are fulfilled and proven by independent tests. Usually used copper gaskets can be used for all nominal diameters. This also emphasizes the flexibility and supplier independence.

Our VaCFix® Clamp chains are also applicable for the connection of KF and conical ISO flanges.

VACOM provides CF flanges and components of the dimensions DN10 to DN400 according to ISO / TS 3669-2:2007. These flanges are fully interchangeable with ConFlat® and CF flanges of other manufacturers.

Please consider that the ASTM standard as well as individual standards of institutions are also available in the market. Please add in case of requests of CF components of the sizes (DN25, DN50, DN75, DN125) and nominal diameters from DN250 the size and the number of required bolts and the necessary copper gasket.

Dimensions of CF Flanges

Nominal diameter AD
[mm (inch)]
AD Cu gasket
Bolt circle
Number of
DN10  25 (1”) 6 13 18 6 x M3
DN16 34 (1.33”) 7,6 21 27 6 x M4
DN25 54 (2.12”) 11,5 33 41 4 x M6
DN40 70 (2.75”) 13 48 59 6 x M6
DN50 86 (3.38”) 16 61 72  8 x M8
DN63 114 (4.5”) 17,5 82 92  8 x M8
DN75 117 (4.62”) 17,5 91 102 10 x M8 
DN100 152 (6”) 20 120 130 16 x M8 
DN125 171 (6.75”) 21 141 152 18 x M8
DN160 203 (8”) 22 171 181 20 x M8
DN200 254 (10”) 25 222 232 24 x M8
DN250 305 (12”) 25 272,7 284 32 x M8
DN275 337 (13.5”) 28 294 306 30 x M10
DN300 368 (14.5”) 28 326 338 32 x M10
DN350 419 (16.5”) 28 376 389 36 x M10
DN400 470 (18.5”) 28 424 438 40 x M10