Backup Ring, Back-up, O-Ring, Square, Quad, PTFE, Polyurethane

Backup Ring

Seal & Design offers Back-up Rings made of several materials including PTFE, Polyurethane, polyester, nylon and leather.

  • The Purpose of the Back-up Ring is to stop O-Ring extrusion between the rod and the bore. Normally used in applications where pressure is 2500 PSI or higher.

backup ring


Square Ring

Square Ring

Originally, square and rectangular cut rings were used in static applications as a direct replacement for O-Rings. They were considered a inexpensive, loose-tolerance alternative to molded O-Rings. Because they are fabricated from a cylindrical tube of rubber which is extruded, the inside and outside diameters are defined and the part is specified by dimensioning the inside diameter and wall thickness. The tube is then machined into various cross-sectional configurations by using a precision grinder or lathe-type cutting machine. By using the process of extruding material, expensive molds are not required giving designers flexibility in sizing to their exact requirements.

Square rings are considered an economical alternative to O-Rings, particularly in static applications.

  • They seal in a superior manner, at a lower cost than any other comparable device.
  • They use the same groove as O-ring
  • They can be used for radial seals
  • They are made of homogenous material without joints or laminations
  • The edges are accurately formed
  • Surface smoothness, hardness, elasticity, toxicity and texture can be controlled
  • The modern, economical option for static applications
  • Available in many compounds


Quad Rings

Quad Rings

Quad-Ring® Seals are four-lipped seals with a specially developed sealing profile that actually provides twice the number of sealing surfaces as an O-ring. The four-lobed design not only provides lower fiction than an O-ring, but also, due to its square cross section, it resists spiral twist. Quad-Ring® Seals are available in a wide range of elastomer materials for both standard and special applications. Quad-Ring ® Seals are vulcanized as a continuous ring. Their dimensions are specified with the inside diameter "d1" and the cross-section "W." Quad-Ring® Seals are supplied to the American Standard AS-568A and are completely interchangeable with O-rings in these sizes. Quad-Rings® Seals are available in all standard O-Ring sizes from 1/32" to 26", as well as custom seals for unique applications.


  • There are two sealing surfaces to give a positive seal with less friction. Due to an improved pressure profile over Quad-Ring© Seal cross-section, a high sealing effect is achieved.
  • The recessed mold parting line provides no flash or parting line on the surface of the seal and ensures "zero leakage." What's more, a lubricant reservoir formed between the sealing lips improves performance at start-up.
  • The quad cross-section resists spiral twisting and extrusion. Due to its special profile, the seal does not tend to twist in the groove during reciprocating movement.
  • Twice the sealing surface means less radial squeeze is needed to create an effective seal resulting in less friction, less wear and longer service life.