Abstract: A mechanical seal assembly for creating a sealing relationship between a housing and a shaft which is rotatable relative thereto. The seal assembly includes first and second coaxially aligned and axially adjacent seal rings disposed in an encircling relationship to the shaft and having axially adjacent and opposed flat seal faces for creating an annular sealing region therebetween. The first and second seal rings are respectively nonrotatably coupled to the housing and the shaft. A chamber is defined adjacent one seal ring and is in communication with a controlled pressurized fluid source which supplies a fluid to the chamber. The chamber opens toward a rear surface of the seal ring to apply a closing force to the seal ring to axially move the seal ring toward the opposing seal ring.