US Patent 11608898 Externally energized secondary seals in split mechanical seals

A mechanical seal that employs an axially movable spring holder plate that engages a sealing element, such as an O-ring, associated with a stationary seal ring. In turn, the stationary seal ring can have a sealing face that engages with a sealing face of a rotary seal ring. The rotary seal ring can also have a sealing element, such as an O-ring, associated therewith. The O-rings are initially disposed in an unloaded position where they are not radially compressed and hence the ends do not expand circumferentially past the end faces of the holder or gland segments. The spring holder plate can be moved axially by tightening selected bolts associated therewith. When moved axially, the spring holder plate moves the stationary seal ring and the O-ring associated therewith in an axially inboard direction, thus placing the O-rings in a loaded position, where the O-rings are radially compressed.