Need an encapsulated o-ring? No matter the size, big or small, we can help

We stock a large range of FEP and PFA encapsulated o-rings with Silicone and Viton inner core options, alongside circular, square and rectangle design options. We can provide both metric and imperial, as well as Kamlock sizes.

Encapsulated O-rings Guide

Encapsulated ‘O’-Rings consist of an elastomer core with a thin FEP or PFA sheath. The encapsulation is a hard material with limited flexibility compared to a fully elastomeric ‘O’-Ring.

Encapsulated O-Rings are commonly used in the food, pharmaceutical and chemical industries, and others where high chemical resistance and/or hygiene are required. They are better suited to static applications; however, they can be used in a dynamic applications if the movement is slow and short.

The elastomer core is either fluorocarbon (FKM) or silicone (VMQ) and can come in round, hollow or square/rectangular section.

An encapsulated O-ring is often recommended in certain circumstances where:

A standard O-ring has poor chemical resistance for a desired application

A solid PTFE O-ring does not offer the sufficient softness for the application

Sheeth Material Comparison

  •  FEP (Fluorinated Ethylene Propylene)

  • PFA (PerFluoroAlkoxy)

  • Standard material for all applications up to 205°C, resistant to virtually all chemicals and joined by an advanced heat moulding process to give a seamless encapsulation.

  • Same properties as FEP encapsulation but with greater heat resistance for applications above 205°C. Also resistant to virtually all chemicals and joined seamlessly.

  •  - Water Absorption: 0.3%

     - Dielectric Strength: NULL volts per meter

     - Flammability Rating (UL94 Rating): V-0

     - Toughness: NULL

  •  - Water Absorption: 0.1%

     - Dielectric Strength: 1350 volts per meter

     - Flammability Rating (UL94 Rating): V-0

     - Toughness: R25

Inner Core Material Comparison

  • SIlicone (VMQ)

  • Viton (FKM)

  • - Recommended for extreme Temperatures (High or Low)

    - Softer shore hardness - better suited to static applications

    - Resistant to Ozone

    - Compression set Resistant

  • - Recommended for chemical resistance

    - Generally better suited to dynamic applications

    - Resistant to Ozone

    - Compression set Resistant

Encapsulated O-Ring Inner Core Types

Silicone Solid Inner Core

Commercially Silicone is the best material option combined with lower Shore Hardness and greater elasticity than Viton®, providing an excellent material choice for the majority of applications.

Viton Solid Inner Core

As opposed to Silicone, Inner Viton® has greater chemical resistance than Silicone. If encapsulation is damaged, Viton® provides greater resilience to chemical attack.

Silicone Hollow Inner Core

Hollow core flexibility means less firmness to further increase its sealing abilities. Recommend for delicate applications using sensitive materials such as glass or light plastic. Available in Silicone or Viton Materials.

IMPORTANT NOTE! Not to be applied within vacuum applications. Negative air pressure within the hollow core can cause a rupture.

Silicone/Viton Square Section Inner Core

Specifically designed to be a gasket seal, square shaped encapsulated seals are more suited to specific requirements and are available in Silicone or Viton materials.

Silicone/Viton Rectangular Inner Core (Kamlock)

The rectangular shape cross-section is designed to be a universal fit  and precludes the need to specify different elastomers for different applications. This in turn also helps prevent coupling leakage due to a chemical attack or cold extrusion of a solid PTFE gasket seal. These are also available in Kamlock™ sizes.

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