FLEXIBLE MEMBER F018
The portion of the seal containing the springs or bellows. The majority of mechanical seals have only one flexible member but there are a few older designs that spring load both the rotating and stationary faces to prevent excessive seal movement.
If the flexible member rotates with the shaft we say it is a rotating seal. If the flexible member does not rotate we say it is a stationary seal. Both types are used in industry.
Stationary seals are usually more reliable.