Oil and lubrication systems
Consider HNBR where compatible oil exposure combines with heat ageing or mechanical demands. Include the lubricant specification and any additives or cleaning exposure.
BY MATERIAL
HNBR O-Rings — Supply & Application Support
We supply HNBR O-rings and support compound and application review. Start with your drawing, dimensions, existing compound specification, part reference or seal replacement requirement.
Request a Technical Review
Initial response within 12 hours.
01 / HNBR REQUIREMENTS
What HNBR Adds to Material Selection
HNBR is hydrogenated nitrile butadiene rubber. Hydrogenation reduces unsaturation in the NBR polymer backbone, improving resistance to heat ageing, oxidation and ozone. HNBR compounds can also provide useful strength, tear resistance and wear resistance.
Consider HNBR when an oil-resistant seal also faces demanding thermal or mechanical conditions. The right choice depends on the complete compound and sealing arrangement, rather than the material name alone.
02 / HNBR REQUIREMENTS
HNBR, NBR or FKM?
| Selection question | NBR | HNBR | FKM |
|---|---|---|---|
| Is the current oil seal working reliably? | Retain a proven, compatible compound unless requirements change. | Consider a change only for an identified service need. | Consider a change only for an identified service need. |
| Is heat ageing, ozone exposure or mechanical damage driving a change? | Check the existing compound and establish the cause of failure. | A candidate when compatible oil service also requires improved ageing or mechanical performance. | A candidate where a different thermal or chemical requirement justifies review. |
| Must the seal recover during cold starts with oil exposure? | Review a suitable low-temperature compound. | Balance cold recovery against fluid-induced volume change. | Include suitable low-temperature grades; do not judge all FKM by a standard grade. |
| Has the fluid or operating cycle changed? | Recheck compatibility and the existing gland. | Recheck compatibility and the existing gland. | Recheck compatibility and the existing gland. |
The same dimensions and nominal hardness do not establish an equivalent replacement. Fluid swelling, recovery and compression behaviour can change the way a seal works in the existing gland.
03 / HNBR REQUIREMENTS
Why HNBR Compounds Differ
Acrylonitrile (ACN) content affects the balance between resistance to non-polar oils and fuels and flexibility in cold conditions. In comparable formulations exposed to non-polar hydrocarbon oils or fuels, a lower-ACN option may improve cold flexibility but can increase volume swell. The outcome depends on the exact fluid and complete compound.
Hydrogenation level, fillers, plasticizers and the cure system also influence the finished material. Cure options must match the selected polymer grade; they are not interchangeable across every HNBR formulation. Nominal hardness alone does not describe the compound's stiffness, recovery or ageing behaviour.
Compare data for the proposed compound using stated test methods, specimens, temperatures and exposure times. Raw-polymer properties and test-piece results do not establish finished O-ring performance in your equipment.
04 / HNBR REQUIREMENTS
Chemical Compatibility: Identify the Actual Fluid
| Exposure | Information that matters |
|---|---|
| Oils, lubricants and greases | Product specification, base fluid, additives, temperature and duration. Mineral-oil experience does not establish compatibility with every synthetic lubricant. |
| Fuels and fuel mixtures | Fuel specification, aromatic or alcohol content, blend composition and service cycle. Include periods when the seal dries out. |
| Hydraulic fluids | Identify mineral-oil, water-containing or synthetic-fluid chemistry. A hydraulic-fluid label alone is not enough, particularly for ester-based fluids. |
| Coolants, cleaning agents, hot water or steam | Review each exposure and any change between fluids. Include concentration, temperature, pressure and cleaning duration. |
HNBR should not be selected by default for exposure to ketones, esters, ethers, chlorinated hydrocarbons or strong acids. These are risk categories for initial screening, rather than final compatibility ratings for every chemical within them. Review the exact chemical, concentration, temperature and exposure with evidence for the proposed compound. Glycol-based brake fluids should not be treated as a standard HNBR application.
Compatibility involves changes in volume, hardness and mechanical properties. Fluid-induced shrinkage can reduce sealing contact; excessive swelling can increase gland fill and friction. Check the combined fluid and temperature exposure rather than relying on a single temperature rating.
05 / HNBR REQUIREMENTS
Low-Temperature HNBR Selection
Cold conditions can slow elastic recovery as the seal and surrounding components contract. Include cold-start pressure, motion and the time spent at low temperature in the review.
A specific HNBR compound (70 Shore A nominal) showed no cracking at −40°C under ASTM D2137-11 Method C.
Test conditions: 3 minutes at −40°C, T-50 specimen and isopropyl alcohol coolant. This is not a universal HNBR sealing limit or a TR10 result.
These third-party published technical references are not FLUID product test results or performance guarantees. Confirm the supplied compound and operating conditions before use.
06 / HNBR REQUIREMENTS
Seal Design and Leakage Review
Initial squeeze establishes contact. Gland dimensions and tolerances must also leave room for thermal expansion and fluid swelling. Compression-set data describe recovery under defined conditions; they do not directly measure retained sealing force or predict service life.
Dynamic seals additionally depend on motion, speed, surface finish, lubrication and contamination control. A wear-resistant HNBR compound cannot compensate for every design problem. Rotating applications require a dedicated seal-design review.
Pressure peaks, component deflection and clearance can allow extrusion, particularly as the material softens with heat. Higher hardness may help in some arrangements, but clearance control or back-up rings may also be needed. Back-up rings support the seal against extrusion; pressure direction and available groove space must be considered.
| What you observe | What to include in the review |
|---|---|
| Leakage immediately after installation | Dimensions, lead-in edges, threads, lubrication and signs of cuts or pinching. |
| Leakage after hot service or during cold starts | Temperature cycle, fluid exposure, recovery, shrinkage and gland squeeze. |
| Wear marks or spiral cuts | Motion, alignment, surface finish, lubrication and installation history. |
| Nibbled edges or missing material | Pressure peaks, effective clearance, temperature, compound condition and back-up arrangement. |
These observations guide investigation; a damage photograph alone does not establish the cause. Gas service and rapid decompression require separate compound and application evidence.
07 / HNBR REQUIREMENTS
Industrial Applications to Discuss
Hydraulic pumps and valves
Review the fluid chemistry together with pressure cycling, clearances, motion and contamination. A material change alone may not resolve extrusion or installation damage.
Automotive and mobile equipment
Selected oil, fuel and coolant requirements may justify an HNBR review. Confirm the exact fluid and thermal cycle; these are separate from brake-fluid suitability or customer qualification requirements.
Cold-start industrial equipment
Balance oil resistance with cold recovery after exposure and ageing. Include minimum temperature, cold-soak duration and the pressure and motion at startup.
08 / HNBR REQUIREMENTS
Custom and Replacement HNBR O-Rings
FLUID supplies HNBR O-rings and supports review of custom-size and replacement requirements. Share a drawing, dimensions, sample information or an existing part reference so the supply requirement and sealing conditions can be reviewed. For replacement work, include the current compound and the reason for changing it, where known.
Material selection and sealing-arrangement questions can be discussed as part of the technical review. Feasibility, dimensions and tolerances, hardness, quantity and required documentation are confirmed for the specific project before a supply option is agreed.
09 / REVIEW
Share What You Already Have
You do not need a complete specification to begin.
- 01
Drawing, dimensions, tolerances, sample information or part reference.
- 02
Existing compound, hardness, quantity and required documents.
- 03
Exact fluids, concentrations, mixtures, additives and cleaning exposure.
- 04
Minimum and cold-start temperatures, cold-soak duration, continuous conditions and short peaks.
- 05
Working and peak pressures, pressure direction, cycling and any gas exposure.
- 06
Static or dynamic operation, motion, speed, lubrication, gland details and service or damage history.
10 / RELATED PATHS
Continue the technical discussion
11 / TECHNICAL REVIEW FAQ
HNBR O-Ring FAQ
Can HNBR directly replace NBR or FKM?
Not on the material name alone. Compare the proposed compounds against the fluid, temperature cycle, gland and reason for replacement. A suitable material in one application may not be equivalent in another.
Does higher hardness solve wear or high-pressure leakage?
Not necessarily. Review the effective clearance, pressure peaks, temperature, surfaces and lubrication. A harder compound changes compression behaviour and does not remove the need for an appropriate gland or back-up arrangement.
Does the −40°C reference guarantee sealing at −40°C?
No. The reference is a specific brittleness-test result. It does not establish TR10, retained sealing force or leakage performance in a finished gland. The supplied compound and complete operating cycle need review.
Can HNBR be used with fuels, steam or glycol-based brake fluids?
Assess these exposures separately. For fuels, identify the specification, blend composition and additives; compatibility with one fuel does not establish compatibility with every blend. Steam requires evidence for the proposed compound at the actual temperature, pressure and exposure duration. Glycol-based brake fluids should not be treated as a standard HNBR application, and suitability must not be inferred from experience with engine coolant or water-glycol hydraulic fluids.
What if the fluid or compound is unknown?
Send the available product specification, existing part information and operating history. Identify missing information before confirming a material. Where necessary, agree suitable material and application verification for the actual exposure and sealing arrangement.
NEXT STEP
Discuss Your HNBR O-Ring Requirement
Send the information available. We will review the compound, supply requirement and application, and clarify the next information needed.
Request a Technical Review
Initial response within 12 hours.