Abstract: A ferrofluidic seal is fitted with a centering ring having an inner edge adapted for engagement with a rotating shaft for centering the seal about the rotating shaft. The centering ring automatically engages the shaft and centers the seal when the seal is fitted onto the shaft. The centering ring is affixed to the housing, and/or magnet and pole module. In one embodiment, the centering ring may be removed after it performs its centering function. In another embodiment, the centering ring is non-removable and remains within the seal permanently. According to this latter embodiment, the centering ring serves the additional purpose of retaining ferrofluid, expelled from the seal during "bursting", within magnetic reach of the seal so as to be re-drawn into the seal, thus extending seal life. Additionally, a ferrofluid retaining ring absent a centering function may be employed.