Integral magnetic fluid centrifugal high speed gas seal and method

Abstract

A magnetic/centrifugal-fluid seal is characterized by a common region serving as both the magnetic gap for the magnetic seal and a fluid-receiving pool for the centrifugal seal. A magnetically permeable annular rotating member extends radially into an annular space defined by a magnetically permeable stationary member to form an annular space of U-shaped cross-section between the members. A closed magnetic circuit is established through the members and the space, which space thereby acts as a magnetic gap to retain the fluid therein when the rotating member is at rest or rotated at low speeds. The common region also retains the fluid when it is centrifugally pressurized during high speed rotation of the rotating member. The fluid remains substantially in the same location during speed-up and slow-down, thereby avoiding compromise of the seal during speed transitions. Recirculation and replacement of the fluid is achieved in conjunction with an injection port arranged to deliver fluid to the common region through the stationary member. A fluid reservoir includes a sight glass to permit viewing the fluid condition and level and is arranged to selectively deliver fluid to the inlet port by gravity feed. A pump in the recirculation path delivers recirculating fluid to the reservoir from a vent on the low pressure side of the seal.