NKE Sanitary Stainless Steel Tubes, Valves, and Fittings
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KF Flange
KF Union
In the 1950s, the Klein Flange company developed the KF Flange, or Quick Flange (QF) couplings, and ever since, it has been commonly used in vacuum and ultra-high vacuum applications. The easiest way to identify the union is its O-ring seal that is supported by a centering ring. They come in sizes from KF10 to KF50. For sizes larger than KF50, see our ISO Flange Union.
The union contains a KF Clamp, Two KF Flanges, and a KF Centering Ring with Seal. They can be mated with KF Bored Flanges, KF Blanks, and other KF Components. When the flanges are connected, the centering ring provides a seal that prevents air from leaking into the vacuum system, even in conditions with temperature and pressure.
KF flanges are easy to use because they do not require special tools to assemble or disassemble.
Size Range
From KF10 to KF50
Internal Surface Finish
< 1μm
KF Flange
The KF Flanges are the end fittings that will be welded to tubes, fittings and valves. It comes in different lengths but the most common are 12.7mm and 30mm, longer flanges make it easier to be orbital welded. Available in SS 304 and SS 316L.
KF O Ring
The KF O ring sits in the middle of two KF Flanges to act as a seal to prevent leakages. Material is usually Viton which handles a wide range of chemicals and temperature (about -20C to 180C).
KF Clamp
The KF Clamp is used to fasten two KF Flanges together. The clamp compresses the flange and seal to create a seal.
The clamp ring comes with a wing nut so no tools are required, different types that are fastened by bolts and nuts are also available but are not so common. Available in aluminium and SS 304.
KF Blank Flange
The KF Blank Flange is just a KF Flange without an opening, it can replace the KF flange to act as a cover to block flow. It is usually used for leak testing, isolating a section for maintenance, and capping a spare port. Available in SS 304 and SS 316L.
KF Centering Ring
The KF Centering Ring acts as a frame for the O Ring. An outer centering ring is also available if the KF Flange is to handle pressure as well as vacuum.
Available in SS 304 and SS 316L. Centering Rings can also come with mesh to act as a backup filter.
KF Flange Dimensions | SS304 / SS316L | KF / NW / QF Series | High Vacuum Rated
Size | Welding Neck OD (mm) | Flange OD (mm) | Length (mm) |
|---|---|---|---|
KF10 | 12.7 / 14 | 30 | 12.7 / 30 |
KF16 | 19.06 / 20 | 30 | 12.7 / 30 |
KF25 | 25.4 / 28 | 40 | 12.7 / 30 |
KF40 | 38.1 / 44.5 | 55 | 12.7 / 30 |
KF50 | 50.8 / 54 | 75 | 12.7 / 30 |