Capped O-Ring

Product Overview

Capped O-rings are a cost-effective solution for providing cap seals for rod and piston seal applications.

The seal assembly consists of a cap manufactured from one of Eriks premier PTFE compounds and an O-ring to act as the seal energiser.

The design of the capped O-ring protects the elastomer from extrusion and nibbling.  The specially profiled cap element acts as the seal’s dynamic interface and prevents spiral failure and reduces stick slip, commonly associated with O-ring seals.

Our capped O-rings are designed to retrofit existing O-ring grooves, including AS4716 standard housing dimensions. Both metric and imperial sizes are available and can be tailored to fit housing dimensions provided.

Our technical team can also advise on how to optimise O-ring squeeze to minimise seal friction.

Capped O-Ring Product Image

Capped O-Ring Pt No. Format

Elastomeric Energiser Materials

ElastomerColourHardness (IRHD)Temperature RangeSelect for..Compound Reference
Silicone (VMQ) Red 70 -60 to +220oC

High and very low temperature; high eccentricity

Polyacrylate (ACM) Black 70 -10 to +150oC

High temperature capabilities; good compatibility with engine oils


Nitrile Rubber (NBR)

Black 70 -30 to +120oC General Purpose 36624
Fluorocarbon (FKM, A-type) Black 75 -20 to +200oC

High temperature performance; high speed applications; 514141 (Viton® GF type) for improved coolant and fuel resistance

Green 75 -20 to +200oC 51414G
Fluorocarbon (FKM, GF-type) Black 75 -10 to +200oC 514141
Hydrogenated Nitrile (HNBR) Black 70 -30 to +180oC

High temperatures, moderate fuel resistance


PTFE Grade Codes

Material Composition>ColourCoefficient of FrictionTemperature RangeSelect for..PTFE Reference

Virgin PTFE

White 0.05/0.08 -240 to +200oC Static or low duty cycles E400
Glass and MoS2
reinforced PTFE
Grey/Black 0.06/0.10 -160 to +290oC

Dynamic or static, medium duty cycles, hardened metal running surfaces

Graphite reinforced PTFE Black 0.06/0.10 -200 to +250oC

Dynamic, medium duty cycles


Carbon and graphite reinforced PTFE

Black 0.08/0.12 -200 to +250oC Dynamic, medium duty cycles E462
Polyester reinforced PTFE Beige 0.08/0.12 -130 to +290oC

Dynamic or static, medium to high duty cycles, minimum 45 HRc running surface

Carbon, graphite and PPS
reinforced PTFE
Grey/Black 0.08/0.12 -130 to +290oC

Dynamic or static, high duty cycles, hardened metal running surfaces