FEP encapsulated O-rings, also known as encapsulated o-rings, are the ideal solution for demanding environments where chemical resistance must not compromise the elasticity of the seal. Made from an elastomer core (FKM or VMQ) encapsulated in a sealed FEP sheath (or PFA for dynamic applications), these O-rings combine flexibility and chemical robustness, while offering exceptional temperature resistance.

1. What is a FEP Encapsulated O-Ring?

A FEP encapsulated O-ring consists of:

• A flexible elastomer core, providing shape recovery and elasticity,

• A FEP outer sheath (fluorinated ethylene propylene), known for its excellent chemical and solvent resistance.

This type of O-ring is often referred to as an “elastic PTFE”, due to its comparable chemical resistance combined with superior flexibility.

2. Extended Thermal and Mechanical Performance

Depending on the elastomer used, the FEP O-ring covers a wide temperature range:

• FEP/FPM (fluoroelastomer): -20°C to +200°C

• FEP/VMQ (silicone): -60°C to +200°C

• Up to +250°C with PFA sheath for specific applications

• Cryogenic version available with stainless steel spring: effective down to -200°C, ideal for liquid oxygen or hydrogen

These encapsulated O-rings can withstand pressures up to 250 bar, and up to 500 bar with anti-extrusion rings.

3. Key Advantages of FEP Encapsulated O-Rings

• ✅ Excellent chemical and solvent resistance

• ✅ Elastic recovery, unlike solid PTFE O-rings

• ✅ High and low temperature resistance

• ✅ Compliant with FDA and USP standards for food and pharmaceutical applications

• ✅ Cost-effective alternative to FFKM O-rings

4. Technical Data and Installation Guidelines

Available colors and hardness:

• FEP/FPM (black): 90/95 Shore A

• FEP/VMQ (red): 85/90 Shore A

• (optional: 75/80 Shore A on request)

Recommended compression rates:

• 15–20% for static applications

• 10% for dynamic applications (e.g., mechanical seals)

• 5–8% for pneumatic use

Technical limitations:

• Possible ovalization for small inner diameters

• Not suitable for closed groove installations

• Torus diameter limited by sheath size

• Best suited for static assemblies (prefer FFKM Ultima for dynamic constraints)

ULTIMA’s Added Value: Fast, Flexible and Scalable

With ULTIMA, you benefit from a responsive and tailored offer:

• 📦 Large stock = 24h delivery for standard sizes

• 🛠️ No tooling costs

• 🔄 From prototype to medium series production (up to 1,000 pieces)

• 🔧 External diameters up to 3 meters

• ⏱️ Custom manufacturing delivered within 4 weeks

Conclusion

FEP encapsulated O-rings are the perfect compromise between chemical resistance, thermal performance, and mechanical flexibility. Their innovative structure and DMP’s responsive logistics make them a strategic choice for complex industrial environments such as pharmaceutical, food-grade, chemical, and cryogenic sectors.

🔍 Need a quote or technical advice? Contact our team today and benefit from our speed, precision, and industrial expertise!