The Basics of Using O Rings

O rings are staples in the sealing world. They are increasingly common fluid power seals that are made by billions of manufacturers worldwide. They prevent leaks in pumps, valves, connectors, and cylinders, among other things. And, they are rubber sealing products that can handle static and dynamic operations, both in hydraulic and pneumatic applications.

Standard O rings are donut-shaped with a circular cross-section and are usually made from elastomers. They come in different sizes and can be used in a variety of settings. Here are the basics you need to know about these rubber sealing products.

How Do O Rings Seal?

Rubber O ring seals work using mechanical deformation, creating barriers to any potential fluid leak paths between closely aligned surfaces. They are installed in grooves that are either molded in one of the surfaces that will be sealed or machined. With the properties they contain, they compensate for any dimensional differences between the two surfaces. As those surfaces make contact, the O rings are compressed, deforming the round cross-section. This ensures that the seal is squeezed diametrically, ensuring surface contact between inner and outer gland walls.

The natural resiliency within the material provides the seal, keeping fluid from passing through. At higher pressures, standard O rings deform into a D shape. The contact area between the elastomer and the gland surfaces could double from initial, pressure-free conditions. When the pressure is released, the O ring returns to its original shape and is now ready for the next application of pressure.

Be aware that in extreme-pressure applications, elastomer material is forced up into the small clearance between mating surfaces and beyond the groove. The material in rubber O ring seals flows into the extrusion gap, causing the seal to fail.

Always Consider The Design

Even though standard O rings are easy to use, design considerations have to be made so that they can best fit certain materials. They come in several materials and several compounds. When the material meets the application, that is when you’ll achieve fluid compatibility while using the rings. This allows them to best withstand extreme temperatures and contrasting environments.

Consider conditions, such as rotary or axial, as well as the operating pressure and whether the system will see pressure spikes. As a result, design parameters such as proper gland dimensions, gland surface finishes, material hardness, initial compression, seal cross-section diameter, and many others can be properly specified. As long as the seals are properly designed, they’re an easy fit for countless applications.

Standard O rings are straightforward and versatile enough that you can use them across many applications. These products keep things sealed for as long as possible, and as effectively as possible.