| 摘要 |
A mechanical seal for providing a fluid-tight seal between a rotating shaft and a stationary housing comprises a first pair of seal members for sealing and separating a process fluid from a barrier fluid. The first pair of seal members comprises a first rotatable seal ring having a rotary seal face and a first stationary seal ring having a stationary seal face engaging the rotary seal face. The first pair of seal members further includes generally radially extending piston areas on the rear sides of the primary seal members for biasing seal faces together. The piston areas are defined by a movable shuttle member that is connected to the rotary seal ring and a sleeve, which is in turn connected to the rotating shaft. Under normal operating conditions, the shuttle is moved to a first position to allow the process fluid to exert a force on a first piston area to bias the seal faces together. Under reverse operating conditions, when the barrier fluid pressure is greater than the process fluid pressure, the shuttle member is moved to a second position where it exerts a force, along with the barrier fluid, on a second piston area to bias the seal faces together. |
