by Sara McCaslin, PhD Sara McCaslin, PhD No Comments

As long as your application involves static pressures, no extremes in either temperature or pressure, and no corrosive chemicals, an elastomeric o-ring will probably suffice. But things become more challenging outside of those conditions and you will need a better sealing solution: a spring energized seal.

O-Ring Seals

O-rings are a common type of seal that’s used in a wide variety of applications. Elastomeric o-rings are made from materials such as silicone, Neoprene, Nitrile, Buna N, and EPDM Rubber and consist of a toroid with a circular cross-section. In fact, the official definition of an elastomer component is that it does not break when stretched 100% (i.e., stretches to twice its original length). 

O-rings can effectively provide a barrier to prevent fluids from leaking and work well for static applications and some dynamic applications as long as there are no extremes in pressure or temperature. However, there are times when a spring-energized seal provides a better sealing solution than an o-ring. 

O-rings often fail due to issues with clearance as high pressures, large temperature changes, or cyclical changes in either pressure or temperature, all of which can cause dimensional changes that force the o-ring into the seal extrusion gap and cause excessive wear that leads to premature failure. In addition, environmental conditions and temperature changes can lead to the elastomeric material becoming brittle, thus losing its ability to stretch and compromising its ability to provide an effective seal.

Spring-Energized Seals

The spring energizer seal is the engineer’s choice when O-Rings cannot provide adequate seal performance.The energized seal applies a consistent force that enables the lip to adapt to the contact surface as it rotates. Because of this, spring-energized seals are often used to effectively maintain a seal even when there are challenges such as vacuum pressures, eccentric contact surfaces, runout, and hardware gaps. In short, where other static and dynamic sealing options fail, spring-energized seals rise to the task.

Operating Conditions Where Spring-Energized Seals Excel

Despite the additional cost, spring-energized seals are preferred over elastomeric o-rings when there are …

  • Extreme pressures (including vacuum pressures)
  • Extreme temperatures (including cryogenic environments)
  • Dynamic (as opposed to static) pressures
  • Corrosive media (when materials such as PEEK and PTFE are used)
  • Cyclic pressures or temperatures

In such conditions, even the best elastomeric O-rings will start losing their ability to seal. They can become brittle in extreme temperatures, and exposure to corrosive media will accelerate their natural wear. Using O-rings in such operating environments can seriously compromise the reliability of equipment and the safety of personnel, not to mention potential environmental impacts.

Additional Benefits

Also keep in mind that spring-energized seals are available with FDA approved jacket materials such as PTFE and PEEK that make them safe for use in applications such as food processing, pharmaceutical, biochemical, and medical. Their extreme durability makes them ideal for harsh environment industries such as petrochemical, oil and gas, and aerospace. 

Conclusion

When all other sealing solutions fail, a spring-energized seal is likely the answer. They consistently provide reliable sealing in operating environments that destroy o-rings, and in turn enhance the dependability, safety, and performance of the equipment that depends on them for proper operation. 

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