Encapsulated O-rings

Totally Seals Encapsulated O-rings Silicone Viton Hollow Kamlock


We stock a large range of FEP or PFA encapsulated o-rings with Silicone or Viton inner core, and in circular, square or hollow cross sections. We can provide both metric and imperial as well as Kamlock sizes.

We are proud to distribute high quality and UK supplied products with same day dispatch (before 2pm), next day delivery (UK) and Global Shipping Options.

  • UK Supplier with guaranteed customer service
  • Order before 2pm to qualify for next day delivery
  • Custom sizes can be produced on request


Totally Seals® 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

FEP / PFA Encapsulation 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 via advanced heat moulding process.


  • 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


Silicone (VMQ) vs Viton (FKM) Inner Core Material

SIlicone (VMQ)

Viton (FKM)

Recommended for extreme Temperatures (High or Low) Recommended for chemical resistance
Softer shore hardness - better suited to static applications Generally better suited to dynamic applications
Resistant to Ozone Resistant to Ozone
Compression set Resistant Compression set Resistant


Inner Core Types

Silicone Solid 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 Core

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

Hollow 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.

Square Section 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.

Rectangular 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.