| Property | Value |
|---|---|
| Temperature range | -40 °C to +120 °C |
| Hardness | 40–90 Shore A |
| ACN content | 18–50 percent, and it decides everything below |
| Contains fluorine | No |
ACN content is the spec that matters
Nitrile is a copolymer of butadiene and acrylonitrile, and the acrylonitrile fraction, the ACN content, is the number that sets how the compound behaves. ACN is not a quality grade. It is a trade-off you pick, and picking it wrong is the most common reason a nitrile part disappoints.
| ACN content | What you gain | What you give up |
|---|---|---|
| Low, around 18–28 percent | Cold flexibility, a seal that still works well below -40 °C | Oil resistance, more swell in fuel and aromatic oils |
| Medium, around 33 percent | The general-purpose balance most nitrile parts use | Nothing in particular, and nothing exceptional either |
| High, around 40–50 percent | Maximum resistance to fuel and aromatic oils, minimum swell | Low-temperature performance, brittleness in the cold |
You cannot have both ends. A high-ACN compound that shrugs off gasoline will stiffen and leak on a cold morning, and a low-ACN compound that stays flexible at -45 °C will swell in the same fuel. When we quote a nitrile part, the service temperature floor and the media together pick the ACN. That is why we ask about both.
Where nitrile fails
Ozone cracking is the usual one. Nitrile has unsaturated double bonds in its backbone, and atmospheric ozone attacks them, so a part under tension outdoors develops fine surface cracks perpendicular to the strain and then splits. This is not heat and it is not the fluid. It is the air. Antiozonants in the compound delay it, they do not remove it, so a nitrile part that will live outdoors under stress is the wrong specification rather than a compounding problem.
The other limit is heat. Nitrile is comfortable to about 100 °C continuous and can be pushed to 120 °C, above which it hardens, loses elongation, and takes permanent set. If your part is running at 130 °C in oil, nitrile is not the answer and HNBR usually is, at a fraction of the cost of going to FKM.
Typical uses
- O-rings, rod seals, and shaft seals in hydraulic and pneumatic systems
- Fuel-system components, hoses, and gaskets
- Flat and profiled gaskets in oil-wetted joints
- Dynamic seals where abrasion and tear resistance matter, an area where nitrile beats FKM
What we do with it here
Nitrile is one of the families we mix ourselves, so ACN content, filler loading, and cure system are formulation choices we make against your application rather than a catalog number we order in. Compounds are verified in our ISO/IEC 17025:2017 accredited lab before they are molded, and finished parts are tested in the same building.