HNBR 70 Durometer
HNBR 70 is a 70 durometer Shore A hydrogenated nitrile butadiene elastomer classified ASTM D2000 BH. The compound delivers 2321 psi tensile strength and 250% ultimate elongation across an operating range of -58°F to +275°F. HNBR is evaluated as a cost-effective alternative to FKM (Viton®) in select high-performance applications requiring resistance to heat, oil, and chemicals.
Key Properties
- Hardness: 70 Shore A (± 5)
- Tensile Strength: 2321 psi
- Ultimate Elongation: 250%
- Compression Set: 10 to 50% (general HNBR)
- Temperature Range: -58°F to +275°F
- ASTM D2000 Classification: BH
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- Specifications
- Applications
- General Info
- FAQs
Physical Properties
| Property | Value | Test Method |
| ASTM D2000 Classification | BH | ASTM D2000 |
| Hardness | 70 Shore A (± 5) | — |
Mechanical Properties
| Property | Value | Test Method |
| Tensile Strength | 2321 psi | — |
| Ultimate Elongation | 250% | — |
| Compression Set (general HNBR range) | 10 to 50% | — |
Thermal Properties
| Property | Value | Test Method |
| Temperature Range | -58°F to +275°F | — |
Aging Performance — Heat Aging (70 hours at 302°F, general HNBR)
| Property | Value | Test Method |
| Change in Tensile | 10 to 30% | — |
| Change in Elongation | 30 to 50% | — |
| Change in Hardness | 10 to 15 points | — |
Aging Performance — Fluid Immersion (70 hours at 302°F, general HNBR)
| Property | Value | Test Method |
| IRM 901 Oil Immersion | 0 to 5% | — |
| IRM 903 Oil Immersion | 0 to 30% | — |
Performance Profile
| Property | Value | Test Method |
| Abrasion Resistance | Excellent | — |
| Impact Resistance | Excellent | — |
| Weather Resistance | Excellent | — |
| Ozone Resistance | Excellent | — |
| Oxidation Resistance | Excellent | — |
| Heat Resistance | Good | — |
| Tear Resistance | Good | — |
| Chemical Resistance | Good | — |
| Gas Permeability | Fair | — |
| Radiation Resistance | Fair | — |
| Ability to be Colored | Fair | — |
| Flame Resistance | Poor | — |
Chemical Compatibility
| Property | Value | Test Method |
| Petroleum-Based Fluids | Generally chemically resistant | — |
| Oxidizing Agents | Generally chemically resistant | — |
| High Temperature Steam | Generally chemically resistant | — |
| Polar Organic Solvents | Generally chemically attacked | — |
| Oxidizing Acids | Generally chemically attacked | — |
| Chlorinated & Aromatic Hydrocarbons | Generally chemically attacked | — |
Compliance
- ASTM D2000 — Compliant (Classification BH)
- Made in the USA
- Automotive timing belts, hoses, and seals
- Oil and gas industry sealing
- Aerospace components
- O-rings, gaskets, and seals
- Splices, large O-rings, and oilfield seals
Common industries: automotive, aerospace, and oil and gas.
HNBR 70 is a 70 Shore A hydrogenated nitrile butadiene elastomer within the HNBR product family. The hydrogenation process removes unsaturation in the polymer backbone, enhancing stability and durability while retaining the strong oil and petroleum resistance characteristic of nitrile rubber. The 70 Shore A grade is the most common general-purpose hardness for sealing applications, offering a balance of conformability and resilience in automotive timing belts, hoses, seals, and oilfield components.
Mechanical performance for this grade is characterized by 2321 psi tensile strength and 250% ultimate elongation across a service temperature range of -58°F to +275°F. HNBR exhibits excellent abrasion, impact, weather, ozone, and oxidation resistance, with good heat, tear, and chemical resistance, and is generally chemically resistant to petroleum-based fluids, oxidizing agents, and high temperature steam.
The material has fair gas permeability, radiation resistance, and ability to be colored, and is poor in flame resistance. HNBR is generally chemically attacked by polar organic solvents, oxidizing acids, and chlorinated and aromatic hydrocarbons.
For the general HNBR product family, heat aging at 70 hours at 302°F produces tensile change of 10 to 30%, elongation change of 30 to 50%, and hardness change of 10 to 15 points; IRM 901 oil immersion at the same condition produces 0 to 5% change and IRM 903 oil immersion produces 0 to 30% change. Made in the USA.
Compliant with ASTM D2000 Classification BH.
What differentiates HNBR 70 from softer or harder HNBR grades?
At 70 Shore A, this grade is the most common general-purpose hardness for HNBR sealing, sitting between the softer 60 Shore A (more conformable) and the firmer 75 and 80 Shore A grades (greater extrusion resistance). It pairs that balanced durometer with 2321 psi tensile strength and 250% ultimate elongation, making it the default selection for automotive timing belts, hoses, and oilfield seals.
Why is heat and oil resistance critical for this material?
The defining function of HNBR is sustained sealing and structural performance in elevated-temperature service in contact with petroleum-based fluids. Standard elastomers can soften, swell, or degrade under continuous oil exposure at high temperatures, leading to seal failure in automotive, aerospace, and oilfield equipment. HNBR is formulated to resist that degradation, with documented performance after 70 hours at 302°F in IRM 901 (0 to 5% change) and IRM 903 (0 to 30% change) oils.
What is the temperature range for HNBR 70?
The operating temperature range for the 70 Shore A grade is -58°F to +275°F.
Is HNBR 70 suitable for oilfield, automotive, and aerospace environments?
Yes. HNBR is classified ASTM D2000 BH and is generally chemically resistant to petroleum-based fluids, oxidizing agents, and high temperature steam, making it suitable for oilfield seals, automotive timing belts and hoses, and aerospace components. Note that HNBR has poor flame resistance and is generally attacked by polar organic solvents, oxidizing acids, and chlorinated and aromatic hydrocarbons — these conditions should be evaluated for any specific application.
How should HNBR 70 be specified?
Specify grade (HNBR, 70 Shore A), thickness or part geometry, ASTM D2000 line callout if required, compliance requirements, dimensional tolerances, and finished format (sheet, O-ring, gasket, molded component, splice, etc.).
