These KF-50 centering ring vacuum fittings are supplied with chemical resistant Perlast G75B O-ring material and are designed for use with standards ISO-KF 50 (NW-50) vacuum fittings. The O-ring material, Perlast G75B, is well known for its excellent resistance to heat (617°F/325°C), medium – high pressure applications and to aggressive fuels and chemicals, has exceptional acid and amine resistance, re-usability and conformity at high temperature, extremely low outgassing, good steam resistance, and good performance with oils @200 deg C temperatures. Perlast G75B Perfluoroelastomer (FFKM) is considered to have the widest possible operating range of chemicals and operational temperatures applicable for a variety of applications which makes it a popular choice for use in high-technology vacuum areas.

These KF-50 centering rings are commonly used to build fore-line vacuum piping inside chemical process systems, semiconductor, oil, and gas connections. They are often called quick flange fittings because they are quick to assemble. A circumferential clamp and centering ring form the vacuum seal between the connecting flanges (please see top right figure - click to enlarge). The centering ring contains a rubber elastomer O-ring, chemical resistant Perlast G75B material. The standard sizes for quick flange fittings are KF-10, KF-16, KF-25, KF-40, and KF-50 with flange sizes NW-10, NW-16, NW-25, NW-40, and NW-50, respectively. Perlast G75B is a Perfluoroelastomer (FFKM) and registered trademark of DuPont Performance Elastomers.