Air Side: The side of a seal that normally faces away from the fluid being sealed.

Air Side Angle: The angle between the air-side surface and the shaft. Also barrel angle.

Angle, Contact Approach: See angle, outside lip.

Angle, Helix: The angle between a helical rib and the lip line of contact.

Angle, Helix Contact: The angle formed by the rib leading edge and the lip line of contact.

Angle, Helixseal Rib: The angle formed by the leading edge of the rib and a line perpendicular to a plane tangent to the outside lip surface at the centerline of the rib base.

Angle, Inside Lip: The angle between the inside lip surface and the axis of the seal case.

Angle, Molded Toe: The angle between the toe face of a seal lip and the seal axis.

Angle, Outside Lip: The angle between the outside lip surface and the axis of the seal case.

Angle, Trimming: The angle between the trimmed face of a seal lip and the seal axis.

Assembly, Seal: A group of parts that includes sealing surfaces, provisions for initial loading and a secondary sealing mechanism, which accommodates the radial and axial movement necessary for installation.

Axial Clearance: See Clearance, Axial.

Base, Seal: See Face, Outside Seal.

Bedding-In: See Run-in.

Bell Mouth: A condition where the contact between the sealing element and the shaft occurs on the air side of the seal and not on the seal tip.

Blister: A raised cavity or sack that deforms a surface of the seal material.

Bond: The adhesion established by vulcanization between two cured elastomer surfaces, or between one cured elastomer surface and one nonelastomer surface.

Bore, Housing: A cylindrical surface that mates with the outside diameter of the outer seal case.

Bore, Seal Case: See Diameter, Outer-Case Inner.

Buna-N: See Nitrile.

Cap: The part of the seal head section that is removed during trimming.

Case, Bonded: A design feature of a type of radial lip seal wherein the heel of the sealing element is attached to the seal case by an adhesive during the molding operation.