Nitrile is the most widely used elastomer in the seal and o-ring industry. Its popularity results from the ability to sustain performance across a wide temperature range (-22F to 212F), and its excellent resistance to petroleum-based products. Additionally, nitrile material exhibits superior compression set, tear and abrasion resistance. Limiting properties of nitrile include poor ozone and weather resistance, with only a moderate resistance to high heat. However, in many applications these are not restricting factors. Nitrile is often referred to as Buna (Buna-N) and NBR.
The nitrile AS908-70N o-ring can be reference in one of four ways:
The final consideration for an o-ring after size and material type is the durometer. Durometer is an industry standard measurement for a material’s hardness. Most often for rubber seals, durometer is measured and listed in accordance with the “Shore A” scale. Typical durometers for standard rubber seals are 70, 75 and 90, depending on the material. A higher number indicates a harder material. Durometer is also generally stated and accepted with a “+/- 5” tolerance. For nitrile o-rings, standard nominal durometers are 70 and 90.
O-Rings, rubber seals and custom molded rubber components for:
|-22`F / -30`C||212`F / 100`C|
|Oils & Grease|
AS568-908 (Durometer 70) cross reference sizes