Abstract: A mechanical face seal includes a pair of relatively rotatable seal rings having opposing seal faces which define a sealing region therebetween. The sealing region extends radially between the inside and outside diameters of the seal rings to seal a fluid in a sealing chamber near one diameter thereof. The seal faces are provided with hydrodynamic lift features near the sealing chamber to provide a lift load that permits a liquid between the seal faces to form a fluid film therebetween. The hydrodynamic lift features primarily function to hydrodynamically generate a hydrodynamic lift load while a plurality of concentric grooves are also provided on the seal face to serve as a leakage barrier during shaft rotation of the that prevents the liquid film from leaking across the seal faces.

Abstract: A controllable mechanical seal for sealing a shaft rotatable relative to the housing of a fluid machine includes first and second face elements having first and second radial surfaces. The first element is adapted for rotation with the shaft. The second element is adapted to be stationary within the housing. One of the elements is movable axially relative to the shaft. The first and second surfaces are adapted to define a gap within which there is a thin lubricating fluid film. An actuator is provided for deforming at least one of the surfaces so that the gap converges in a direction from a high pressure side to a low pressure side of the seal. A sensor is provided for measuring a temperature indicative of incipient contact of said surfaces. A control system responsive to the sensor generates an external voltage which is applied to the actuator to control the convergence of the surfaces and thus maintain an optimum thickness of the lubricating film for a wide range of operating conditions.