Encapsulated O-rings

encapsulated o rings

FEP Encapsulated O-Rings / PFA Encapsulated O-Rings

FEP encapsulated O-rings comprise of an elastomer core which has been seamlessly encapsulated in a jacket of Teflon® fluoropolymer. The core is either Viton ®, Silicone or EPDM. The jacket is FEP or PFA.

FEP encapsulated O-rings are recommended when a standard O-ring has inadequate chemical resistance for an application. They are also recommended when a solid PTFE O-ring does not have the elasticity for reliable, long term fluid sealing. They are often used where chemical resistance and or hygiene is required.

Typical industries include:

UK Seals Ltd can provide practically any size of encapsulated rings. We hold many sizes in stock. We offer solid and hollow core styles as well as cam and groove gaskets.

FEP profile options

Inner Core / Profile Options

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

Viton® inner core
Greater chemical resistance than Silicone. If the encapsulation is damaged, Viton® provides greater resilience to chemical attack.

Silicone hollow inner core
Greater compressibility than a solid Silicone core, with a hardness similar to a standard elastomeric O-ring. The hollow core flexibility means less clamping force is required to enable its sealing abilities. Hollow cores are ideal for fragile applications using sensitive materials, such as glass or light plastics. They are also useful when the sealing area may require room for movement during operation.

Silicone/Viton® square/rectangular core – Kamlock® seals
Designed to be a gasket seal, as opposed to an O-ring. The rectangular cross section is designed to be a universal fit, non-contaminating Kamlock® hose coupling seal. It eliminates the need to specify different elastomers for different applications and stops coupling leakage due to chemical attack or creep of a solid Teflon® gasket seal.

Custom core profile
We also supply special custom profile and ring shapes to your application needs – please contact us for more information.

Encapsulated O-rings are available in cross sections from 1.78mm to 25.4mm. The only size limits are with the smaller ID’s. Please check our size limitation chart as the diameter of the cord dictates the smallest possible ID.

FEP encapsulated O-rings offer excellent resistance to a wide range of chemicals. They offer typical temperature ranges of:
-60°C to +200°C with Silicone core.
-20°C to +200°C with Viton ® core.

They offer low friction and a low ‘stick-slip’ effect.

PFA encapsulated O-rings offer extra abrasion resistance. When combined with a Silicone core, they offer a temperature range of -60°C to +260°C.

We also supply PFA encapsulated O-rings with a Viton ® core. These seals offer a temperature range of -20°C to +200°C. Viton ® core PFA encapsulated O-rings also provide extra abrasion resistance.


FDA & NSF 61

The clear Teflon FEP / PFA encapsulation complies with Part 177 of Title 21 of the Food and Drug Administration regulations for safe use as articles or components of articles for producing, manufacturing, processing, preparing, treating, packing, transporting or holding food in accordance with FDA regulation 21.CFR.177.1550.

The clear Teflon FEP / PFA encapsulation of our encapsulated O-rings is compliant to NSF 61 requirements.

We confirm that we do not use any part of the Jatropha plant in the manufacture of our FEP/PFA Encapsulated ‘O’-Rings.


Teflon ® FEP / PFA fluoropolymers have been tested in accordance with USP Protocol. They meet the requirements of a USP Class VI plastic. Only the FEP / PFA encapsulation comes into contact with the product. Our FEP / PFA encapsulated O-rings are considered to be USP Class VI compliant. For information on our core materials, please read our material data sheets.

EU VO 1935/2004 and 10/2011

UK Seals & Polymers Ltd has researched and evaluated BFR documentation. We have paid particular attention to “Recommendations of the Federal Institute for Risk Assessment on Plastics intended to come in to contact with Food”. Any material or article intended to come into contact, directly or indirectly with food, must be sufficiently inert to prevent substances from being transferred to food in quantities large enough to endanger human health, or to bring about an unacceptable change in the composition of the food or a deterioration in its organoleptic properties.

The outer encapsulate is an FEP or PFA melt process-able polymer of PTFE. PTFE is also known as the brand Teflon ®. PTFE polymers are highly inert. They are often used in industrial food processing, and domestic food cooking equipment.

Our FEP / PFA encapsulated O-rings manufacture is compliant with all relevant sections (1 to 21) of the E.C Regulation Number 1935/2004 and the subsequent Articles.

We are pleased to advise that our FEP / PFA encapsulated O-rings are compliant to EU VO 1935/2004 and 10/2011 certification.

To find out more information on our FEP encapsulated O-rings, please visit our Downloads section.