Patent ID: 6371488
Filing Date: 2002-04-16
Classification: F04D,F16J

Abstract:
For a closed system for containing liquid operating at elevated pressures in excess of 1000 psi, a sealing system for a pump having a stationary housing with highly pressurized liquid therein and having an inlet section exposed to high pressure and an outlet section exposed to lower pressure and a shaft in said housing with a rotational axis, said sealing system including a primary pressure breakdown sealing arrangement and a back-up pressure breakdown sealing arrangement disposed in series in the direction of fluid flow from said inlet to said outlet of said housing, each of said sealing arrangements forming a seal gap between a rotatable component thereof and a relatively stationary component thereof, each sealing arrangement sealably mounting said shaft relative to said housing,said primary sealing arrangement comprising a radially extending seal runner, rotatable with said shaft, having a radially extending annular runner seal face thereon, an axially movable relatively stationary sealing ring encircling said shaft, and a ring sealing face thereon confronting said runner seal face, respectively, a secondary seal being sealably mounting said seal ring relative to said housing except along the seal gap formed between said ring sealing face and said runner seal face; said primary sealing arrangement being positioned between said shaft and said housing such that the higher pressure liquid passes from said housing inlet to the one end of its seal gap which is exposed to higher pressure and along said seal gap to the other end thereof where the pressure has normally been broken down to lower pressure, and said back-up sealing arrangement being positioned between said shaft and said housing such that said other end of the seal gap of the primary sealing arrangement is in flow communication with the higher pressure end of the seal gap of said back-up sealing arrangement; said primary sealing arrangement being of the hydrostatic type and formed to have a limited but finite leakage flow through the seal gap and wherein fluid pressure is broken down along its seal gap irrespective of the rotation of said shaft, said back-up sealing arrangement being of the hydrodynamic type wherein the pressure across its seal gap is broken down to effect pressure breakdown between said shaft and said housing only when said shaft is rotating, and said backup sealing arrangement being shaped so that its seal gap is closed when said shaft is not rotating to prevent any leakage across the seal gap thereof unless said shaft is rotating.