What are Encapsulated or Coated O-Rings?
They are actually two different types of O-Rings. Encapsulated O-Rings are an O-Ring (usually silicone or FKM) covered with a PTFE (a generic compound of Teflon™, a trademark of The Chemours Company) tube. Encapsulated O-Rings are specifically designed to address the problem of sealing the most hostile chemicals and extreme temperature applications. Encapsulated O-Rings consist of a solid or hollow elastomeric core encapsulated in a PTFE FEP or PFA sheath. Solid core encapsulated O-Rings are generally used in static applications. Hollow Silicone core encapsulated O-Rings are commonly used in applications where lower sealing force is required as in semi dynamic applications. The encapsulated O-Ring offers an effective solution for many difficult applications. The PTFE FEP or PFA encapsulation actually affects the seal and the elastomeric core ensures consistent compression on the seal. The result is an overall sealing compression, increasing with medium pressure. The encapsulated O-Ring behaves like a highly viscous fluid, any pressure exerted on the seal is transmitted in all directions. Maximum operating temperature for FEP is 205°C (400°F) and for PFA 260°C (500°F).
Encapsulated O-Ring dimensions comply with International O-Ring dimensional standards. The encapsulation does not increase the cross section compared to a standard elastomer of the same size.
Coated O-Rings are Teflon coated, with the coating adhering to the O-Ring (usually silicone or FKM), versus the encapsulated which are a Teflon tube over the O-Ring.
PTFE coating of O-Rings is an ideal low-friction coating where operational flexibility is a major consideration. PTFE also offers additional benefits such as:
- Positive identification at the assembly line
- Ease of installation
- Lower break-in torques
- Reduces costly “hang-ups” on automatic systems
- Lower initial running friction
- Eliminates sticking of components after long storage
- Reduces twisting of rings during installation
Coatings are often available in standard blue, medium blue, light blue, white, purple, red, yellow, medium green, dark green, grey, clear, black, orange, brown umber, pink and green/gold.
Coated O-Rings are Teflon coated, with the coating adhering to the O-Ring (usually silicone or FKM), versus the encapsulated which are a Teflon tube over the O-Ring.