Rubber elastomer mechanical seals are designed with rubber bellows. Rubber provides the secondary seal between each seal face and adjacent seal ring. One seal ring is fixed statically using an o-ring or cup gasket.The other is spring-loaded and requires a semi-dynamic seal to accommodate some axial play,such as a dynamic o-ring in pusher-type mechanical seal face seals or elastomeric bellows in non-pusher ones.The semi-dynamic applications(involving flexing and sliding of the elastomer)can be crital for maintaining proper contact between the faces through face friction,shaft movements etc.
Multiple spring mechanical seals are designed with multiple springs in the compensating parts and pressure of the springs are relatively well-distributed,suitable for pumps with high speed and large diameters. The weak point is that the diameter of the spring is small so that the granular crystals will make the spring fail.
