Sealing Concept

The Delta® seal is a member of the Helicoflex family of spring energized seals. The sealing principle of the Helicoflex family of seals is based upon the plastic deformation of a jacket that has greater ductility than the flange materials. This occurs between the sealing face of a flange and an elastic core composed of a close-wound helical spring.

The spring is selected to have a specific compression resistance. During compression, the resulting specific pressure forces the jacket to yield and ensures positive contact with the flange sealing faces. Each coil of the helical spring acts independently and allows the seal to conform to irregularities on the flange surface.

The Delta® seal is unique in that it uses two small ridges or “Deltas” on the face of the seal. The load required to plastically deform the jacket material is greatly reduced by concentrating the compression load on the Deltas. The resulting high contact stress in the seal track makes the Delta seal an excellent choice for ultra-high vacuum applications that require ultra-low Helium leak rates. There is typically no risk of damaging the flange sealing surfaces as long as the minimum hardness requirements are maintained.