Effect of Operating Parameters

  • Speed is related to the generated friction between the seal and the dynamic sealing surface and, therefore, affects the performance of the seal. Low speeds will cause increased friction; high speeds will cause a breakdown in the oil film between the seal and the sealing surface, causing the seal to run dry, thus leading to premature seal failure.
  • The frictional heat generated when the seal operates may accelerate hardening of the seal material, particularly in the contact area between the sealing lip and the sliding surface. This leads to cracks which become increasingly larger over time and ultimately result in seal failure. Therefore, to maximize the service life of a seal, as little frictional heat as possible should be generated in the contact area between the seal and the sliding surface.
  • High pressure causes extrusion of the seal into the extrusion gap, which exists on the no-pressure side of the seal. The gap can be increased with a corresponding lowering of operating pressure or with the use of an anti-extrusion or back-up ring.
  • High or low temperature beyond the seal material’s specified temperature range affects the seal significantly. The seal will become brittle if the temperature is too low or too high. Heat damage is irreversible and leads to reduced seal life.
  • Higher temperature softens the seal/back-up ring material, resulting in greater seal extrusion and increased friction, leading to reduced seal life.