Patent ID: 8356972

Claim:
A shutdown seal for surrounding a rotating shaft and preventing a fluid in an annulus surrounding the shaft from leaking past the shutdown seal after the rotation of the shaft has slowed or is not rotating, comprising: a constrictable split ring surrounding the shaft, the split ring having confronting ends and an inner diameter spaced from the shaft when the shaft is rotating, the inner diameter defining a portion of the annulus; a spacer disposed between the confronting ends of the split ring for maintaining the annular space between the confronting ends during normal operation of the shaft, the spacer is operable to be removed from between the confronting ends when the liquid rises above a pre- selected temperature so the split ring can constrict to narrow or substantially seal a portion of the annulus; a generally rigid retaining ring encircling and spaced along the shaft upstream, in a direction of flow of the liquid, from the split ring, the retaining ring having an inner diameter spaced from the shaft when the shaft is rotating, the inner diameter defining a portion of the annulus; and a pliable polymer ring surrounding the shaft and positioned between the split ring and the retaining ring, the polymer ring having an inner diameter spaced from the shaft when the shaft is rotating, the inner diameter defining a portion of the annulus, the pliable polymer ring being urged toward the shaft by a pressure differential across the polymer ring when the split ring is constricted and moves into the annulus towards the shaft.