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FAQ: Teflon® Encapsulated O-Rings

WHAT IS ENCAP-O-SEAL™?

ENCAP-O-SEAL® is the trade name of M-COR, Inc.’s Teflon® encapsulated o-ring. This product represents our commitment to providing high-quality, chemically resistant seals. Furthermore, the unique properties of ENCAP-O-SEAL® make it suitable for a wide range of industrial applications.

WHAT IS A TEFLON® ENCAPSULATED O-RING?

A Teflon® encapsulated o-ring is a universal chemical-resistant seal used in industry to prevent the passage of corrosive fluids or gases. It consists of two components: (1) a Teflon® encapsulation (i.e., jacket or covering) and (2) an elastomer (i.e., rubber) core material, which completely encloses the core. Therefore, this combination provides excellent chemical resistance and durability for various industrial applications.

WHAT IS AN ELASTOMER?

An elastomer is a general term for elastic, rubber-like substances.

Shelf Life:

Encapsulation Materials:
FEP – Unlimited shelf life
PFA – Unlimited shelf life
Elastomers:
Viton – 20 years
Silicone – 20 years
EPDM – 5 to 10 years

WHAT IS THE REASON FOR ENCAPSULATING A RUBBER CORE MATERIAL WITH TEFLON®?

The Teflon® encapsulation, which is virtually chemically inert, allows the o-ring to resist nearly all chemicals, thereby extending seal life and preventing contamination. Additionally, the elastomer core material imparts its mechanical properties to the o-ring. Unlike solid TFE o-rings, Teflon® encapsulated o-rings resist cold flow. Consequently, this synergy gives Teflon® encapsulated o-rings their unique properties: chemical resistance, anti-stick qualities, resilience, and resistance to cold flow.

WHAT TYPES OF TEFLON® ARE USED TO ENCAPSULATE THE RUBBER CORE MATERIAL?

M-COR, INC. uses only the highest quality certified virgin Teflon® resins: FEP and PFA. Consequently, our products exhibit superior chemical resistance and durability. Additionally, by selecting these premium resins, we ensure that our Teflon® encapsulated o-rings meet the stringent requirements of various industrial applications. Furthermore, the use of certified virgin resins guarantees consistent performance and reliability.

WHAT IS TEFLON® FEP?

Teflon® FEP fluorocarbon resin is a melt-processible copolymer of Tetrafluoroethylene and Hexafluoropropylene. It is practically chemically inert, has an operating temperature of 205°C (400°F), and possesses the highest molecular weight of the FEP family of resins. It withstands chemical attack at elevated temperatures. DuPont invented Teflon® FEP resins, which became commercially available in 1960. Engineers specify Teflon® FEP encapsulation for corrosive-resistant seals with operating temperatures up to 205°C (400°F).

WHAT IS TEFLON® PFA?

Teflon® PFA fluorocarbon resin is a melt-processible copolymer of Tetrafluoroethylene and Perfluorinated vinyl ether from the Perfluoroalkoxy group. It is practically chemically inert, has an operating temperature of 260°C (500°F), and has one of the highest molecular weights of the PFA family of resins. Consequently, Teflon® PFA withstands chemical attack at elevated temperatures. DuPont invented Teflon® PFA resins, which became commercially available in the 1970s. Engineers specify Teflon® PFA encapsulation for corrosive-resistant seals with operating temperatures up to 260°C (500°F). Therefore, it is an ideal material for a wide range of industrial applications.

WHAT TYPES OF ELASTOMER (RUBBER) CORE MATERIAL ARE USED IN M-COR’S TEFLON® ENCAPSULATED O-RING?

We use specially formulated, high-temperature FDA-compliant, and USP Class VI Compliant elastomers. These include solid core and hollow core Dow Corning® silicone, as well as Chemours solid core or hollow core Viton®. Additionally, EPDM is available upon request. Furthermore, Viton FDA Compliant material is also offered upon request. Consequently, we ensure that our elastomers meet diverse application needs and stringent regulatory standards.

WHAT ARE THE ADVANTAGES OF USING A VITON® ENCAPSULATED O-RING RATHER THAN A SILICONE ENCAPSULATED O-RING?

If the application involves a wide temperature range in diverse chemical service, a Viton® core is likely the better choice. Chemical permeation can compromise the core material in some cases. Additionally, Viton® has a greater range of chemical compatibility than silicone core and may extend seal life. *See Gas Permeability.

WHAT IS A HOLLOW CORE O-RING AND WHY IS IT USED?

ENCAP-O-SEAL® hollow core o-rings consist of two components: (1) a Teflon® encapsulation (i.e., jacket or covering) and (2) an elastomer (rubber) hollow core material, which is completely enclosed within the Teflon® encapsulation. Consequently, M-COR, INC. encapsulates hollow-core o-rings to create a softer durometer seal, thereby reducing the amount of clamping force needed. As a result, the durometer of our standard hollow core ENCAP-O-SEAL® o-ring decreases by approximately 10%. Moreover, M-COR, INC. can design special core configurations to meet specific durometer requirements. Therefore, engineers specify ENCAP-O-SEAL® hollow core o-rings in applications where clamping force is minimized due to other mechanical design considerations. For instance, example applications include ID/OD static or dynamic cylinder o-ring glands, hand-tightened lids, caps, and more.

Is the ENCAP-O-SEAL Teflon Encapsulated O-Ring FDA and USP VI compliant.

The materials of manufacture are compliant with the above regulations.

WHAT IS DUROMETER?

Durometer is a numerical scale for measuring the hardness of rubber.

What is the Durometer of the Teflon® Encapsulation?
55 Shore D.

WHAT ARE THE DUROMETERS OF ENCAP-O-SEAL® O-RINGS?

ENCAP-O-SEAL® solid silicone core: 85-90 Shore A.
ENCAP-O-SEAL® solid Viton® core: 90-95 Shore A.
ENCAP-O-SEAL® hollow core silicone: 70-80 Shore A.

WHAT IS HARDNESS SHORE A?

Hardness Shore A is the durometer reading in degrees of the hardness of rubber. Specifically, Shore A hardness of 35 is considered soft, whereas 90 is considered hard. Therefore, understanding these readings is essential for selecting the appropriate rubber material for specific applications.

DO TEFLON® ENCAPSULATED O-RINGS MEET AS568 STANDARDS?

All Teflon® encapsulated o-rings are manufactured to meet AS 568 standards as closely as possible. However, Teflon® encapsulated o-rings have greater cross-sectional and inside diameter tolerance ranges than AS 568 standards. Teflon® encapsulated o-rings are not necessarily molded products; thus, all inside diameter tolerances conform to those for straight-length, unspliced extrusions. Therefore, M-COR, INC. adheres to the highest precision standards published in the RMA HANDBOOK (Rubber Manufacturers Association).

WHAT QUALITY CONTROL STANDARDS OR INSPECTION CRITERIA DO YOU USE?

Due to the critical sealing applications of ENCAP-O-SEAL® Teflon® encapsulated o-rings, strict quality control standards must be met. Therefore, cross-sectional and inside diameter dimensions must first meet the criteria set forth in the Tolerance Chart section of our Quality Manual. Additionally, by using the RMA handbook, an o-ring inspection guide for surface imperfections control, M-COR, INC. has published a quality control manual. This manual establishes quantitative levels of acceptance for ENCAP-O-SEAL® Teflon® encapsulated o-rings relative to imperfection type, size, and quantity (*See Quality Assurance Blog). Consequently, this ensures that our products meet the highest standards of quality and reliability.

WHAT IS THE RMA HANDBOOK?

The RMA Handbook, researched and published by the Technical Committee of the Rubber Manufacturers Association, describes visual quality acceptance criteria for o-rings. Additionally, the Rubber Manufacturers Association is a cooperative manufacturing trade association. Consequently, the handbook provides essential guidelines for ensuring the quality and reliability of o-rings in various applications.

WHAT IS COLD FLOW?

Cold flow denotes continued deformation under stress. Consequently, it is an important factor to consider in the design and application of seals. Furthermore, understanding cold flow helps engineers select the appropriate materials that can withstand prolonged stress without significant deformation.

WHAT IS COMPRESSION SET?

Compression set is the decrease in thickness of a rubber specimen, which has been deformed under specific conditions of load, time, and temperature. Consequently, understanding compression set is crucial for ensuring the durability and effectiveness of rubber seals in various applications. For more information, see the Compression Set Blog.

WHAT IS A COPOLYMER?

A copolymer is a polymer consisting of two different monomers chemically combined. Consequently, this chemical combination results in unique properties that can be tailored for specific applications. Furthermore, understanding the structure of copolymers is essential for selecting the right materials in various industrial processes.

WHAT IS A CROSS-SECTION?

A cross-section is an o-ring as viewed if cut at right angles to the axis. Consequently, this view allows for a detailed examination of the o-ring’s internal structure. Furthermore, analyzing the cross-section is crucial for assessing the quality and consistency of the o-ring’s material and construction.

WHAT IS A CURING DATE?

The cure date denotes when the manufacturing process is complete and the o-ring is ready for shipment.

WHAT IS A STATIC APPLICATION?

A static application is a stationary application.

WHAT IS A STATIC SEAL?

A static seal works between parts having no relative motion.

WHAT IS A DYNAMIC APPLICATION?

A dynamic application is one in which the o-ring is subject to movement or moving parts.

WHAT IS A DYNAMIC SEAL?

A dynamic seal prevents leakage past parts that are in relative motion.

WHAT IS EXTRUSION?

Extrusion denotes distortion under pressure that forces the seal into the clearance between mating metal parts.

WHAT IS A GLAND?

A gland is a seal assembly groove, including the o-ring, the groove, and the mating/sealing surfaces.

WHAT IS HOMOGENEOUS?

A homogeneous material has uniform composition throughout.

WHAT IS PERMANENT SET?

Permanent set is the deformation remaining after a specimen has been stressed in tension for a prescribed amount of time and then released for a definite period.

WHAT IS PERMEABILITY?

Permeability is the property of rubber, plastic, or other materials that permits the passage of gas through the molecular structure of the material.

WHAT IS A POLYMER?

A polymer forms by joining together many (poly) individual units (mer) of a monomer.

WHAT IS RESILIENCE?

Resilience refers to the ability to return to an original size and shape after deformation.

WHAT IS RMS?

RMS stands for Root Mean Square: the measure of surface roughness, obtained as the square root of the sum of the squares of micro-inch deviations from true flatness.

WHAT IS THE ACTUAL SIZE?

The actual size is the precise dimensions of the o-ring, including tolerance limits.

WHAT IS THE NOMINAL SIZE?

The nominal size is the approximate size of the o-ring in fractional dimensions.

WHAT IS SPECIFIC GRAVITY?

Specific gravity is the ratio of the weight of a given substance to the weight of an equal volume of water at a specified temperature.

WHAT IS SQUEEZE?

Squeeze is the cross-section diameter compression of an o-ring between the bottom surface of the groove and the surface of other mating metal parts in the gland assembly.

WHAT IS STRESS?

Stress is the force per unit of the original cross-sectional area required to stretch a specimen to a stated elongation.

WHAT IS O-RING SWELL?

Swell is the increased volume of an o-ring caused by immersion in fluids.

WHAT IS TENSILE STRENGTH?

Tensile strength is the force in pounds per square inch required to rupture a specimen of rubber material.

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