CF-couplings

CF couplings are generally used in high vacuum and ultra high vacuum. It is not as quick to replace as ISO-K / KF but has other advantages instead. The coupling is very common in various applications within HV and UHV and many times a standard for systems where the leakage has to be minimal.
The sizes available commercially span DN16-DN300. Since the application area is HV and UHV, all parts should be very clean and stored except for the risk of contamination from particles or dirt.

Sealing principle

Between two flanges a metal seal (usually copper) is placed. As the bolts are tightened (crosswise), the knife edge of the flanges cuts into the metal seal and gradually seals the entire coupling joint. The bolts are advantageously pulled with a torque wrench. The torque depends on the bay bolt size used (indirect flange size) between 9 Nm-45Nm (see catalog for more information).

Installation:

Place an OFE copper gasket against the blade edge with clean lint-free gloves. Secure the two flanges with a bolt. The first bolt must ensure that the gasket is stationary and does not move during the remainder of the assembly and support the gasket from falling out of position. With the gasket in place, align all holes in each location, leak test grooves should be in the same place. Then install the bolts into bolts and tighten. Trays are usually used on the nut side of the fastener.

”Anti-seize” floating locking is recommended for attaching all stainless steel hardware. This is especially true with holes or blind holes. Retighten all bolts and nut. The tightening process must be done gradually from a quarter to a half step, in an alternating cross pattern. Continue until the desired torque rating has been reached. In this way, a reliable seal with an even gasket ensures compression and deformation.