Ferrofluidic seal
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A ferrofluidic magnetic seal is a sealing mechanism used in rotating equipment to contain a fluid by means of a physical barrier in the form of a ferrofluid. The ferrofluid is suspended in place by use of a permanent magnet.
[edit] Benefits and limitations
Ferrofluidic seals theoretically are low to no maintenance seal, with no wear parts, and little leakage across the seal, they provide little friction or drag to the shafts they seal and can be configured to operate within fluid property, temperature and pressure ranges other seals fail to meet.
The limitations of ferrofluidic seals are similar to many other seals, they can not withstand extreme pressure differentials, and must be stacked in order to withstand large pressure drops. The ferrofluid under certain conditions can break down, and must be maintained over time. Although leakage rates are extremely low, the seals are still susceptible to leakage. Ferrofluidic seal example The seals are also limited in temperature range to the curie temperature of the magnet keeping them in suspension.
