08 Oct The Benefits of NBR (Buna-N) O-Rings
Synthetic elastomers are human-made rubber-like materials that provide specific properties natural rubber cannot deliver, like improved chemical resistance or temperature stability. Nitrile rubber, commonly known as NBR or Buna-N, is a prime example of one used in seal manufacturing.
NBR O-rings have earned a solid reputation through decades of reliable performance across countless industrial applications. Our sealing experts at I.B. Moore Manufacturing recommend NBR when circumstances warrant its use.
What Makes Buna-N O-rings Special?
NBR O-rings offer an impressive combination of properties that make them suitable for a wide range of environments. The material demonstrates excellent resistance to petroleum-based oils, fuels, and hydraulic fluids; those qualities make it the go-to choice for automotive and industrial machinery. This oil resistance stems from the acrylonitrile (a chemical compound) content, which also contributes to the material’s strength and abrasion resistance.
Temperature tolerance is another key advantage. Buna-N O-rings typically perform well between -40°F and 250°F (-40°C to 121°C), so they’re suitable for most standard operating conditions. The material maintains its flexibility and sealing capability throughout this range, for consistent performance in fluctuating temperatures.
Cost-effectiveness further drives NBR O-ring’s appeal. Compared to specialized elastomers like fluorocarbon or silicone, nitrile rubber has a lower price point without compromising performance in appropriate applications. That advantage makes Buna-N O-rings an ideal solution for budget-conscious projects that demand reliable sealing.
Typical Applications for Buna-N O-rings
NBR O-ring applications range from automotive systems to heavy machinery:
- Automotive Systems: Fuel injection systems, transmission seals, and engine gaskets rely on NBR’s resistance to petroleum. These components endure continuous exposure to gasoline, diesel, and motor oils while maintaining tight seals in the face of vibration and thermal cycling.
- Hydraulic Equipment: Industrial hydraulic systems depend on Buna-N O-rings for cylinder seals, pump components, and valve assemblies. The material’s compatibility with mineral-based hydraulic fluids prevents swelling and degradation, for leak-free operation under high pressures.
- Manufacturing Machinery: Production equipment, pneumatic tools, and conveyor systems use NBR seals in moving parts subject to repetitive motion. The material withstands constant compression cycles without losing its sealing capability or dimensional stability.
- HVAC and Refrigeration: Commercial air conditioning units, refrigeration systems, and climate control equipment incorporate NBR O-rings in compressor assemblies and refrigerant lines. The seals maintain system pressure while resisting the mineral oils used in many refrigeration applications.
- Heavy Equipment: Agricultural tractors, excavators, and construction machinery require seals that tolerate harsh conditions. NBR handles exposure to dirt, mud, and multiple fluid types while delivering the durability these rugged applications demand at a reasonable cost.
The Limitations of NBR O-rings
While NBR O-rings offer the advantages outlined above, other conditions exceed their capabilities. The material exhibits poor resistance to ozone, weathering, and UV exposure; therefore, we don’t recommend it for outdoor applications without protection. Prolonged exposure to sunlight and atmospheric ozone causes NBR surface cracking and deterioration.
Chemical compatibility is another consideration. NBR performs poorly with ketones, esters, chlorinated hydrocarbons, and strong acids. Applications involving these chemicals often require alternative elastomers, such as fluorocarbon or EPDM. Steam and hot water above 212°F (100°C) also rapidly degrade nitrile rubber.
Temperature extremes beyond NBR’s range necessitate the use of different materials. High-temperature applications exceeding 250°F require fluorocarbon or silicone compounds, while extreme cold below -40°F demands specialized low-temperature formulations or alternative elastomers.
We include NBR O-rings in both our standard and custom O-ring kits.
Custom O-Ring Kits From I.B. Moore Manufacturing
Companies that manage diverse equipment applications or multiple production lines benefit significantly from I.B. Moore Manufacturing’s custom O-ring kits. Our well-designed kits place the most commonly needed seals at your fingertips, reducing emergency ordering costs and minimizing downtime. It can also save money compared to buying the parts separately. Our team can create custom O-ring kits tailored to your specific equipment inventory and maintenance history.
Designing a custom O-ring kit is a straightforward process. You can select the materials, or we’ll make recommendations. Once the sizes and types are determined, you can order what you need; we’ll package it to your specifications. We also offer a broad range of standard O-ring kits.
Get Your Sealing Solutions from I.B. Moore Manufacturing
Finding the right O-ring solution doesn’t have to be complicated. I.B. Moore Manufacturing offers high-quality NBR sealing solutions, with a focus on material compatibility. Our technical team will help you choose the most suitable material, size, and hardness for your application, for optimal performance and longevity. Contact our Lexington, KY team for nationwide service.