Secondary gas/liquid mechanical seal assembly

摘要

A secondary mechanical seal assembly is used on a shaft that is rotatable within a housing to seal both gaseous and liquid medium. The assembly includes a stationary seal face element that is fixed relative to the housing and a rotating seal face element that is fixed relative to the shaft. One of the seal face element back surfaces includes at least one slot configured to produce a wave on the front surface of the seal face element when the shaft is rotated. The wave creates an opening force that is sufficient to control wear and prolong seal life when the secondary seal assembly is exposed to a gaseous medium. When exposed to a pressurized liquid medium, the hydrodynamic loading from the liquid medium alters the seal face element waviness, and increases the closing force due to the action of the pressurized liquid on the back surface of the seal face elements, such that excessive leakage is prevented.