Precision Polymer Engineering Ltd

Cap Seals

Cap seals offer a low friction seal for use in dynamic reciprocating applications.

A plastic cap provides a seal against the dynamic sealing face, an O-ring is used to energize the plastic cap and operates in a static environment. The O-ring uses the system pressure to increase the sealing force acting on the cap. The cap also prevents extrusion of the O-ring energizer when used in high pressure applications.

The plastic cap is typically made from a low friction material, such as PTFE. Under low pressure conditions, liquid media can provide lubrication as it migrates between the dynamic sealing faces through a capillary effect. Cap seals are often referred to as wet seals as they allow a small amount of fluid to pass across the seal.