Buna Nitrile O-Rings

Buna Nitrile O-Ring Material Description

Nitrile rubber (NBR) o-rings, also known as Buna-N, are one of the most commonly used sealing elastomers due to their resistance to petroleum-based fuels and lubricants and their relatively low price. Nitrile elastomers are copolymers of acrylonitrile and butadiene. (Learn why NBR is a popular choice). There are a number of common variations of nitrile compounds. Nitrile o-rings may also come in a metal-detectable variation while retaining the same qualities as the general Nitrile o-ring compound.

For applications requiring o-rings with high visibility, High-Visibility Nitrile o-rings are recommended. High-Visibility o-rings maintain properties identical to its original compound, with the addition of a distinguishable neon green hue.

Acrylonitrile Content

The acrylonitrile (ACN) content of the polymer chains can vary from 18% to 50%. Lower ACN content gives better low-temperature properties but inferior resistance to fuels and polar lubricants. Higher ACN content gives lesser quality low-temperature properties but improves fuels and polar lubricants resistance. Standard NBRs typically have 34% ACN content.

Cure System: Sulfur-Cured & Peroxide Cured

Standard Nitrile o-rings are usually sulfur-cured. Sulfur-cured compounds offer better low-temperature properties but are more prone to hardening with high temperatures. Peroxide-cured nitrile o-rings have better heat resistance and lower compression sets but are more expensive and more difficult to process. Standard materials in stock include sulfur-cured 70 & 90 durometers (N70, N90) and peroxide-cured 90 durometer (N90PC).

Buna Nitrile Compounds

Compounds	Durometer	Color	Temp Range (F)	Data Sheet	Description
N50	50	Black	-40 to +212		General purpose
N70101	70	Black	-31 to +248		General purpose
N70118	70	Black	-40 to +212		NSF 61, FDA
N70126	70	Black	-40 to +212		UL 157 Approved
N70130	70	Black	-67 to +212		General purpose, low temp resistance
N70312	70	Blue	-40 to +212		Metal/X-ray detectable, FDA-Grade
N70710	70	White	-40 to +212		General purpose, FDA-Grade
N75GR12	75	Green	-40 to +212		Metal/X-ray detectable, FDA-Grade
N90101	90	Black	-4 to +248		General purpose
N90130	90	Black	-65 to +300		Low Temperature
N90HG	90	Green	-4 to +248		High visibility
N90PC	90	Black	-20 to +257		Peroxide-Cured