What Are NBR Rings And How Can They Be Used?

Posted by Linda Hudson on July 30th, 2018

When you talk about O-rings, they are doughnut-shaped rings or a loop of elastomer that has a round cross-section.  Their main purpose is to create a seal at the interface and they are designed in a way that can be seated in a groove and be compressed during assembly between the two parts.

Can be used in Static & Dynamic applications

An O-ring may be used in static applications, where there is no movement between the interfaces. They can also be used for dynamic applications where there is a relative motion between the parts and the O-ring. For instance, you may find these NBR O-rings being used in rotating pump shafts and also hydraulic cylinder pistons.

These rings can be manufactured easily and they are inexpensive, reliable and can be mounted easily and that is why most common seals are used in the design of the machines.

NBR (Nitrile rubber) is the general term given to Acrylonitrile Butadiene Copolymer. These are the most economical form of economical elastomer. These rings gave the great quality of resisting to petroleum-based oils and fuels. Whether they are silicone greases, or hydraulic fluids or water and alcohols they can be used with it.

It offers many desirable properties which include a low compression set, has the high tensile strength and also offer a high level of abrasion resistance.

Design of O-ring requires mechanical mounting that applies a predictable deformation to the ring.   It means that there is a calculated stress at the surface of the O-ring. The ring doesn’t leak till the time the pressure of the fluid that is contained is not exceeding the contacting stress.

The seal is designed to have a contact point between the O-ring and the various sealing faces. It means there is high local stress which is able to tackle high pressure without passing the yield stress of the O-ring body. As the rings are flexible as well so they can handle the imperfections in the mounting parts.

Sizes

These rings are available in various sizes. The SAE is the body that provides the specifications for the inside diameters, cross-sections, tolerances and the size identification codes. The dimensions are measured in

• Internal Dimension (ID)
• Outer Dimension(OD)
• Thickness and Cross-Section (CS)

Finally,

NBR O-rings are known for their good mechanical properties and their resistance to lubricants, greases, and lower costs.