These Ferro-Magnetic Fluid sealed rotary feedthroughs are sealed to the baseplate by a fluorocarbon o-ring. The operator mounts these drives to the vacuum chamber by placing them in a suitable smooth-sided port in the chamber wall and using a capture nut. Some models are threaded only part way. They will accommodate various wall thicknesses when used with a sleeve or spacer over the unthreaded portion so that the nut compresses the o-ring.
In vacuum practice, the o-ring is compressed against the vacuum chamber's inner surface to limit virtual leaks. As shown in the dimensional drawings, most of these Ferro-Magnetic Fluid sealed feedthroughs are designed to be installed this way. A few, however, are intended to have the o-ring sealing against the atmosphere side surface. To reduce the virtual leaks associated with the thread, the feedthrough has a flat machined along the length of its threaded portion.
Please refer to the technical notes about loading, temperature, and other relevant information before specifying a feedthrough.