O-rings, also known as packing or toric joints, are hoop shaped gaskets designed for machinery. The difference between O-rings and more commonly referred to gaskets is that O-rings are almost exclusively used for very high-pressure applications such as hydraulics where a regular cork, paper or rubber gasket would fail. O-rings are usually compressed between two or more larger parts during assembly, creating a seal. They are used to keep fluid or air in or out of a defined space.
Although they are traditionally round in shape and come in standard sizes, you may be able to buy custom O-rings in variable sizes and shapes.
They are extremely common in machine design due to their affordability, reliability, and simple mounting requirements.
For more on industrial O-rings and mechanical component goods, contact Real Seal today for export performance solutions.
But what are Encapsulated O-Rings?
Traditional O-rings are made from elastomer. Elastomer is a synthetic rubber-like material which, at room temperature, can be easily bent or stretched and, when released, quickly returns to its approximate original dimensions and shape. Under normal conditions this is very useful. But sometimes, high temperatures or corrosive conditions make the use of the use of elastomer unacceptable. In these cases, we turn to O-rings made from other materials that can withstand harsher conditions.
What are Encapsulated O-Rings made of?
Encapsulated O-rings have two parts: an inner core made of flexible rubber, and an outer jacket made of Teflon. The rubber gives the O-ring elasticity, and the Teflon gives it protection against corrosion and resistance to high temperatures.
Core Types
Solid Core: Solid core O-rings are filled with either solid Viton® / FKM or silicone. The Viton offers high level compression and elastic qualities. The Silicon is very similar, but because it is softer, it works better under a wider range of temperatures.
Hollow Core: Hollow core Encapsulated O-rings are used in situations where extreme elasticity is needed for maximum flexibility.
Jacket Types
The Teflon jacket of Encapsulated O-rings can be made of either FEP (fluorinated ethylene propylene) or PFA (perfluoroalkoxy-copolymer).
FEP: FEP jacketed O-rings offer resistance to a variety of destructive chemicals. They can be operated under a very wide range of temperatures.
PFA: PFA jackets have many of the same benefits as the FEP jackets. In addition, they are mechanically stronger and resist stress and cracking more efficiently. PFA jacketed O-rings are usually used in situations where extreme durability and thermal stability are required. They also offer a longer service life.
How Are Encapsulated O-Rings Used?
Because their jacket may be damaged by quick-moving parts, encapsulated O-rings are best suited for static machines. However, they may also be used in machines that make slow, short movements such as in valve stem sealing. Powders and slurries can also damage the jackets. Sometimes, these issues can be addressed by adding graphite to the FEP or PFA, making the jackets more durable.
What are the Advantages of Using Encapsulated O-rings?
There are plenty of advantages to using Encapsulated O-rings beyond those already mentioned. They exhibit excellent resistance to nearly all media, with exceptions being alkali metals and some fluorine compounds. They are very well suited for use in the food, chemical, and pharmaceutical industries because they are FDA compliant, and also due to their low contamination and low permeation, among other reasons. Finally, their major lack of friction is preventative of the “stick-slip” effect.
When Should Encapsulated O-rings Not be Used?
As previously mentioned, encapsulated O-rings should not be used in dynamic applications because the outer jacket could be damaged. For the same reason, they should not be used with abrasive media. They cannot be used under high pressure or when highly elongated.
Where are Encapsulated O-rings made?
The two top producing countries of encapsulated O-rings are India and China.
Industrial O-Rings
Real Seal was established in 1970 as a distributor of industrial O-rings, and has since grown into a full-service supplier of sealing and mechanical components. We possess the ability to assist with design challenges, and can custom make materials to meet your specifications. Real Seal offers real solutions at a terrific value.
