Under the condition of shaft rotation, a magnetic fluid feedthrough provides a hermetic seal against both vacuum and gas.

A magnetic loop consists of the magnet, poles and the shaft. Several stages of liquid "O-ring" are formed by the gathering of the magnetic fluid between the poles and the shaft in the presence of magnetic field. Each stage can sustain a pressure of 0.2kgf/cm². There are normally 10 to 20 stages in the sealing part of the feedthrough.

Taking advantage of the superparamagnetic and liquid properties of magnetic fluid, there is no mechanical wear, even at very high rotary speed of the shaft. The magnetic fluid feedthrough is an Ultimate Sealing Component with a long life time. It can be used to sustain pressures from both positive and negative direction.