FEP O-Rings
Hydraulic Seals (FEP O-Rings)
FEP-encapsulated O-rings have a core of elastomer that is completely covered with a seamless sheath of FEP fluoropolymer. The elastomeric core is normally either fluorocarbon (FKM) or silicone (VMQ).
FEP (Fluorinated Ethylene Propylene) O-rings are a type of elastomeric sealing component made from FEP material, which is a fluoropolymer. FEP O-rings are known for their excellent chemical resistance, wide temperature range, and low friction properties. They are commonly used in applications where resistance to aggressive chemicals and high temperatures is required. While FEP O-rings generally refer to O-rings made from FEP material, it’s worth noting that there are variations based on different design aspects.
Here are a few types of FEP O-rings based on their characteristics:
FEP-encapsulated Silicone O-rings: These O-rings have a silicone core material that is fully encapsulated with a layer of FEP material. This design offers the chemical resistance of FEP with the elasticity and low compression set characteristics of silicone. FEP-encapsulated silicone O-rings are suitable for applications where excellent chemical resistance and high-temperature capabilities are needed.
FEP-encapsulated Viton® O-rings: Similar to FEP-encapsulated silicone O-rings, these O-rings have a Viton® core material that is fully encapsulated with FEP material. The combination of FEP and Viton® provides enhanced chemical resistance and high-temperature capabilities. These O-rings are commonly used in applications where resistance to aggressive chemicals and high temperatures is critical.
Advantages
- Outstanding chemical and corrosion resistance
- Reliable, cost-effective and high-performance sealing for many critical applications
- Broad temperature ranges from -60°C (-76°F) to 205°C (401°F), depending on core material choice
- Perfect suited for use in the food, chemical and pharmaceutical industries Physiologically safe (can be sterilized)
- Low permeation rate
- Low friction coefficient prevents adhesion or stick-slip effects (self-lubricating, smooth surface)
- Excellent for high purity processes due to low leach-out
- Good resistance to pressure, deformation and compression
- Square and rectangular cross section are available on demand
Characteristics of various types of FEP O-Ring :
| Type | Characteristics | Temp. range | Hardness |
| FEP encap w/ FKM core | Standard solution. Low comp set, | -20 C to +205 C | 90 to 65 shore A |
| FEP encap w/ silicone core | Better low temp behavior than FKM | -60 C to +205 C | 85 to 90 shore A |
| FEP encap w/ silicone hollow core | Low contact pressure. Used in sensitive equip. Such as glass | -60 C to +205 C | 75 to 85 shore A |
Properties of FEP materials (units based on ASTM standards):
Mechanical Properties
| Property | ASTM unit | Value |
| Specific gravity | D792 | 2.15 |
| Elongation % | D638 | 250~330 |
| Tensile Strength (psi) | D638 | 2800~5000 |
| Flexural strength (psi) | D790 | No break |
| Compressive strength | D695 | 2200 |
| Young’s modulus (psi) | D638 | 50000 |
| Coefficient of friction | On steel | 0.05 |
| Abrasive resistance | Taber | 14~20 |
Thermal Properties
| Property | ASTM unit | Value |
| Melting pt | C | 260 |
| Max. service temp. | C | 200 |
| Linear coefficient of thermal expansion | D696 | 8.3~10.5 |
| Heat of fusion | BTU/LB | 11 |
| Heat of combustion | BTU/LB | 2200 |
| Low temp embrittlement | C | -268 |
