The Differences Between Static and Dynamic O Rings
O rings provide seals between two surfaces and have a wide variety of uses in plumbing and engineering. There are two main types of o ring — static or dynamic. Here are some of the differences between the two.
Static
Static o rings are designed to provide a seal between two surfaces that are not expected to move in relation to each other. As there will not be much friction acting upon the ring, it does not need to be made of such a strong material as a dynamic o ring.
Static rings will generally be set into the seating where they will be compressed by the join. They will therefore need to be highly flexible so that they can tolerate the compression force that will act upon them. The force will tend to flatten the rings, so they need to be able to resist this force to keep the seal intact.
As this is the only force that acts upon the seal, they do not generally suffer wear from being rubbed or abraded. However, you should check them for damage occasionally as variations in temperature or pressure can cause movement in the ring, which could lead to damage on its surface.
Dynamic
Dynamic o rings by contrast are designed to provide a seal between two moving parts. They need to be made of stronger materials than static rings in order to withstand the forces that act upon them.
These forces can easily lead to friction on the rings. In order to avoid this, it is important that the two moving parts are properly finished with no rough edges or jagged surfaces which could catch on the ring or wear it away. Friction can also be reduced by lubricating the o ring. Although all such rings should be lubricated, dynamic rings will need much more than static ones in order to provide a good seal. You will also need to check the rings for damage much more frequently than those in static systems.
You can also reduce wear by using the right ring for the type of motion it will experience. Oscillation or rotary motion, for example, will produce different forces and so will need different types of o ring to withstand them.
In conclusion, make sure you use the right type of o ring according to whether it will be in a static or dynamic system. Your supplier will be able to provide further advice.
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