A mechanical seal device 1 comprises a seal case 30 attached to the device main body, a rotary seal ring 60 attached to the rotary shaft 100, a stationary seal ring 50 arranged in an axial direction opposing to the rotary seal ring 60, and a bellows 40 attached extendably in the axial direction between the stationary seal ring 50 and the seal case 30. A static pressure fluid supplying hole 56, supplying a static pressure fluid to a static pressure fluid chamber C arranged at an inner circumferential side of the bellows, is formed on the seal case 30. A communication hole, guiding the static pressure fluid of the static pressure fluid chamber C to sealing surfaces between the stationary seal ring 50 and the rotary seal ring 60 is formed on the stationary seal ring 50. The sealed fluid is arranged at an outer circumferential side of the bellows 40.

A sliding surface of a first sliding component and a sliding surface of a second sliding component slide against each other in an intersecting manner such that first positive pressure generation grooves and second positive pressure generation grooves at least partially overlap each other. The first positive pressure generation grooves include at least one groove that differs in a position of a terminating end portion from other grooves. The one groove includes a terminating end portion located closer to a sealed fluid space side than a terminating end portions of the other grooves and terminating end portions of the second positive pressure generation grooves.

A representative seal system (such as a seal system for a turbopump of a rocket engine) automatically adjusts a balance ratio of a seal. The system can include a ring element encircling an axis. A front side of the ring element contacts a revolving surface to form a seal with the revolving surface. The front side can include a stepped surface having two or more steps. Each step includes a sealing surface configured to contact the revolving surface to form a sealing area that is different from a sealing area of each other sealing surface. Each step is positioned and configured to wear away during operation of the machine to expose an underlying surface to the revolving surface, to change the sealing area and the balance ratio of the seal. A representative method of operating a turbomachinery system includes changing the balance ratio of a seal while rotating a rotor.