In dynamic sealing applications there is relative movement between the parts of the gland. Thus, O-rings (metal O-rings and metric O-rings) are subject to a sliding action against the gland. This motion introduces friction, which creates design problems different from those of static seals. For the great majority of dynamic applications, O-rings are squeezed radically and are subjected to reciprocating motion (either intermittent or continuous) or, less frequently, to an intermittent rotary or oscillating motion. Special performance seals such as Oil Seals and Energized Hydraulic Seals are also available to meet specific performance requirements.

Reciprocating Seals
This type application involves a relative reciprocating (back-and-forth) motion along the shaft axis between the inner and outer elements of the gland. O-rings used in reciprocating applications are called piston and rod seals. Reciprocating service in aircraft hydraulic systems has been the basis for most of the developmental work and improvements in O-ring sealing technology. Special performance seals such as Oil Seals and Energized Hydraulic Seals are also available to meet your specific performance requirements.

Oscillating Seals
In this application, the inner or outer member of the gland moves in an arc around the axis of the shaft - first in one direction and then in the opposite direction, generally intermittently with no more than a few turns in each direction. The most common application for oscillating O-ring seals is in faucet valves. However, because O-rings help to simplify design and reduce costs, they are used in valves of all types.

Piston Rings
Piston Rings as used in almost all types of engines to complete the sealing of combustion gases and harness the full power of the combustion stroke. This seal provides the engine with a better vacuum to produce a stronger signal to pull fuel and air in for the next combustion occurrence resulting in greater horsepower and torque. Typically, different Piston Rings originate from standards developed by the major engine and ring manufacturers based on tests and data gathered over a long period time. There are often standard rings available for different operating conditions. Piston ring properties are chosen utilizing a combination between material, coating, geometry and gap.

Other Dynamic Seals
O-rings are extremely versatile and may be used in applications where data for ordinary reciprocating or oscillating seals does not apply. For example, O-rings have proven to be practical seals in many rotary applications where either the inner or outer member of the gland elements continuously turn around the axis of the shaft. However, developmental engineering work may be required in these applications. For special applications a seal other then an O-ring may be required. Seal Dynamics offers Oil Seals and Energized Hydraulic Seals for these more demanding applications.