Nitrile Rubber O-rings

Product Description

What are Nitrile Rubber O-rings?

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

Nitrile rubber o-rings can be compounded for enhanced oil and fuel resistance, increased temperature flexibility, high hardness and extrusion resistance, low compression set, and a variety of other attributes. The physical properties of the compound largely depend on the Acrylonitrile content of the formulation. For example, high Acrylonitrile content causes increased oil and fuel resistance while adversely affecting low temperature flexibility and compression set resistance. It is important to consider the offsetting attributes when selecting an NBR formulation.

BUNA-N Nitrile Rubber O-rings Temperature Range

The temperature ranges presented above are approximations for dry air service only and should not be used to determine design specifications or end-use temperature limits. Actual temperature range of a compound in an end-use application is highly dependent on part type, hardware configuration, applied forces, chemical media, pressure and thermal cycling effects, and other factors. The most practical way of determining an end-use temperature range is testing in the actual application conditions. Consult a Marco Engineer for more details.

BUNA-N Nitrile Rubber O-rings Typical Applications

The range of performance characteristics of Buna-N Nitrile rubber o-rings allows it to be utilized in a diverse set of applications. NBR is often used for gaskets and o-rings in pneumatic, hydraulic, and fuel systems. The abrasion and wear resistance of NBR Nitrile rubber o-rings make it useful for dynamic oil seals for rotary and reciprocating shafts. NBR is relatively easy to process which keeps costs down for custom extrusions and complex molds. Hardness ranges from 40 Shore A to 90 Shore A. Hydrogenated versions of NBR (HNBR) have enhanced mechanical properties as well as greater thermal and chemical stability. Specific physical properties and chemical resistances vary by compound formulation.

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.

Cure System: Sulfur-Cured and Peroxide-Cured Nitrile Rubber O-rings

Standard Nitrile rubber o-rings are usually sulfur-cured. Sulfur-cured Nitrile rubber o-rings offer better low-temperature properties but are more prone to hardening with high temperatures. Peroxide-cured nitrile rubber 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 and 90 durometer, and peroxide-cured 90 durometer.

Physical Properties

NBR compound	Hardness shore A	Rubber Color	Temp rang (°C)	Tensile strength (mpa)	Elongation at break (%)
BN005	50	Black	-35 to 120	7.9	480
BN0065	65	Black	-54 to 121	9.5	230
BN007	70	Black	-54 to 120	12.2	180
BN075	75	Black	-54 to 130	12.5	150
BN009	90	Black	-35 to 120	11.8	130
BN009S	90	Black	-54 to 135	12.8	120