SEALS

Outline Fundamentals Fundamentals Selecting a Seal Selecting a Seal Examples Examples Questions Questions

Seal Basics A seal is a part that fits between two mating parts to prevent the passage of fluid between them. A good fluid seal is made when the forces from two mating parts compress or “squeeze” the material and close fluid passageways. There are a wide range of materials and shapes in order to fit various applications.

Design Factors Chemical interactions between seal and fluid. Chemical interactions between seal and fluid. Temperature range. Temperature range. Static or Dynamic application. Static or Dynamic application. Applied pressure Applied pressure Side pressure Side pressure Example of a well designed O-ring seal.

Examples of Poor Seal Design Leaking seal due to insufficient “squeeze”. Extrusion of seal due to inaccurate dynamic design.

Materials Materials used vary widely and are based on application. Materials used vary widely and are based on application. Common materials are Common materials are  Rubber  Fabrics  Metals Examples of fiber-based seals

Selection of Seal After considering design factors, seals are chosen from tables provided by vendors. After considering design factors, seals are chosen from tables provided by vendors. An example of a material selection table.

Examples of Seals Bearing Seal Radial Lip Seals

Seal geometries Examples of seals used in automobiles.

An Innovation in Seal design This seal changes shape to conform to the piston’s vertical position. This seal changes shape to conform to the piston’s vertical position.

Cost Cost for seals depend on size, material, and intended application. Cost for seals depend on size, material, and intended application. Range from a few cents to several thousand dollars. Range from a few cents to several thousand dollars.

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