Teflon encapsulated o-rings are a combination of silicone rubber or FKM Viton rubber on the inside and thin Teflon FEP or Teflon PFA on the outside which has excellent sealing performance. Based on this forming, they are also called PTFE coated o-rings or Teflon coated silicone / Viton o-rings.
Common rubber o-rings are easier to abrade, have poor chemical resistance and gas permeation resistance (except for FFKM / perfluoroelastomer compound), and pure Teflon encapsulated o-rings have higher hardness and compression resistance, but poor elasticity. Encapsulated Teflon FEP / PFA o-rings have good resistance to solvent swelling and chemical stability (unless attacked by metals, fluorine, and some halides at high temperatures). The friction coefficient of Teflon FEP / Teflon PFA is very small (only 0.1~0.2), and it has excellent resistance to gas permeation. These properties make the encapsulated o-rings really applicable in harsh environments.
The manufacture of the Teflon FEP/PFA encapsulated silicone / Viton o-rings is subject to strict quality control, using a special technique that allows the Teflon FEP / FPA material to completely encase the rubber core and guarantees that the Teflon encapsulated o-rings have the required standard tolerances. The data used shows that Savvy Rubber has a good quality commitment to this o-ring product, which is based on performance testing and strict quality control to guarantee customer satisfaction and safe use of this product.
Teflon encapsulated o-rings have unparalleled tightness and long life in a certain respect to any other rubber o-rings, especially in harsh media. Solid encapsulated o-rings are the first choice and are widely used in static and dynamic seals. The cross-section of the hollow silicone ring is generally larger, and its hardness and compression resistance are lower than the solid rings.
- Material: Core – Silicone or Viton; Outer – Teflon FEP or Teflon PFA
- FEP Encapsulated Temperature Range: -60 °C (-76 °F) to 205 °C (401 °F), can be used for a short time at a high temperature of 260 °C (500 °F)
- PFA Encapsulated Temperature Range: -60 °C (-76 °F) to 260 °C (500 °F), can be used for a short time at a high temperature of 300 °C (572 °F)
- Durometer Hardness Range: Silicone Shore A 85-90, Viton Shore A 90-95, FEP / PFA Shore D 55
- Color: Core – orange / black, outer – transparent
- Outline: Round
- Cross Section Shape: Round, and Teflon encapsulated o-ring with square or rectangular cross-sections are usually used in some specific cases
- Cross Section Width (CS): 1.5 to 25 mm (0.06 to 0.98 inch)
- Inside Diameter (ID): 12.7 to 2965 mm (0.5 to 116.732 inch)
- Standard Size: AS 568, BS 1806, ISO 3601, DIN 3771, JIS B 2401
- Shelf Life: About 20 years
- Price Level: Very high
- Outstanding chemical resistance for almost all chemical media
- Excellent corrosion resistance
- Wide temperature range
- Good compression resistance
- Good swelling resistance
- High pressure
- Excellent seal durability and long service life
The combination of the Teflon FEP / Teflon PFA outer cover with a dense and uniform surface and no joints and the rubber inner core makes the overall sealing of the encapsulated silicone (or Viton) o-rings consistent. The elastic and compressive strains at each point on the o-rings are uniform and can be repeatedly installed and used under continuous pressure. As the pressure of the medium increases, the o-rings are compressed as a whole, and these o-rings are like a high-viscosity liquid, which transmits the pressure acting on it to all directions without reduction.
The presence of Teflon FEP / FPA outer coating makes the coated encapsulated o-rings have good resistance to hardening and brittleness, while the inner core is made of silicone rubber or FFKM / Viton rubber making the sealing ring still maintain good elasticity at a high temperature of 200 ℃.
The test result of three o-rings (Garlast® FFKM rubber, FKM rubber, and FEP/PFA encapsulated ) in compression devices show that the Teflon encapsulated o-rings formed by combining the physical properties of silicone or FKM rubber and the chemical properties of Teflon FEP / PFA not only maintain the rubber properties but also have good compression resistance.
Teflon encapsulated o-rings are widely used for special seals on many industrial products, such as pumps, valves, reaction vessels, mechanical seals, filters, pressure vessels, heat exchangers, boilers, pipeline flanges, and gas compressors.
1) The parts of the Teflon encapsulated o-rings are required to be smooth, free of burrs, grooves and sharp corners, the profile of the inner hole should reach 20 milli-inches, and the profile of the shaft should reach 10 inches.
2) Use clean light oil or grease to lubricate the surface of the Teflon coated o-ring and the relevant parts in contact.
3) If the PTFE Teflon encapsulated o-rings are difficult to install on the shaft, they can be immersed in hot water for a few minutes to expand it so that these softened and expanded o-rings are easier to install. Otherwise, install the FEP/PFA Silicone/Viton o-rings when they are hot, and return to their original size when it cools down.
4) Do not bend the o-rings too violently, otherwise, they will cause the wrinkle of Teflon and affect the use.
The required compression of the FEP/PFA encapsulated o-rings is as follows:
Static sealing state: 15%-20%
Dynamic sealing status: 10%-12%
Pneumatic state of encapsulated o-ring: 7%-8%