- Family
- HNBR (hydrogenated nitrile)
- Standard range
- -32 C to 149 C (Parker® O-Ring Handbook ORD 5700)
- Durometers
- By compound; the compound datasheet states the hardness
- Standards
- ASTM D1418 HNBR
- Product
- O-rings in AS568 and ISO 3601 sizes, quoted in the compound the print names
Service temperatures here are the family figures published in Parker O-Ring Handbook ORD 5700A/US §2.2; the compound datasheet and your application govern the final choice.
Larger and non-standard sizes: an O-ring beyond the molded size lists can be supplied as a spliced and vulcanized O-ring, which the maker joins from cord of the same compound. That page lists, family by family, which makers offer the compound as cord, and what to send for a quote.
HNBR O-rings (hydrogenated nitrile) keep nitrile's oil and fuel resistance and add ozone resistance, heat resistance and strength: the Parker O-Ring Handbook (ORD 5700) rates the family from -32 C (-26 F) to 149 C (300 F), against nitrile's 100 C ceiling. It is the automotive air-conditioning, coolant and oilfield seal material. Conquest supplies HNBR O-rings in AS568 and metric sizes.
HNBR O-ring specifications
| Property | Value | Source |
|---|---|---|
| Continuous service temperature | -32 C to 149 C (-26 F to 300 F) | Parker ORD 5700 |
| Material designation | HNBR under ASTM D1418 | ASTM naming |
| Strong against | Petroleum oils and fuels, ozone, water and steam to about 149 C, abrasion | Parker ORD 5700 |
| Weak against | Chlorinated hydrocarbons, ketones, strong acids | Parker ORD 5700 |
Sizes and forms we supply
All 369 AS568 sizes (349 general-purpose dash sizes plus the 20 boss-seal sizes) and the ISO 3601 metric series, in the durometers listed above; O-ring cord for rings spliced and vulcanized by the maker in odd diameters (static service only); and X-rings and backup rings in the same families. The AS568 chart and the metric chart carry the dimensions, and the dash number guide explains the numbering.
HNBR against nitrile and Viton®
| Factor | Nitrile (NBR) | HNBR | Viton (FKM) |
|---|---|---|---|
| Continuous range (Parker ORD 5700) | -34 C to 100 C | -32 C to 149 C | -26 C to 204 C |
| Petroleum oils and fuels | Excellent | Excellent | Excellent |
| Ozone and weathering | Poor | Good | Excellent |
| Hot water and steam to 149 C | Not recommended | Good | Poor in standard grades |
| Chlorinated solvents, aromatics | Not recommended | Not recommended | Excellent |
| Strength and abrasion | Good | Better | Good |
| Cost | Lowest | Middle | Higher |
Typical applications
Automotive air-conditioning seals on R134a and similar refrigerants, engine coolant and oil seals that see under-hood heat, power-steering and transmission hardware, oilfield completion and wellhead equipment where sour gas and heat meet nitrile's media, and outdoor hydraulic equipment where plain nitrile would crack in sunlight.
Ranges are the Parker ORD 5700 figures. Where the only problem with nitrile is ozone or a ceiling a few tens of degrees too low, HNBR is the usual fit before Viton; the Buna-N vs Viton comparison places it, and the temperature range guide lists all three.
Sources: AS568; ASTM D1418; ISO 3601; ORD 5700; Parker O-Ring Handbook.
Parker is a trademark of Parker Hannifin Corporation. Viton is a trademark of The Chemours Company; no affiliation or endorsement is implied.
Reviewed by Grant Midstokke, Conquest Seal Corporation. Last updated September 2026. Material ranges are the published references named beside them; the compound datasheet and your application govern the final choice.
Frequently asked
Where is HNBR used?
Automotive air-conditioning (R134a), engine coolant and oil seals, oilfield equipment, and any nitrile job that also sees ozone or heat.
Is HNBR food grade?
Specific compounds are offered compliant; the compound sheet is the evidence.
HNBR or Viton for a hot oil seal?
HNBR to 149 C; Viton above, or where aromatic fuels and solvents are present.
Does HNBR need a different groove from nitrile?
No. Same AS568 sizes and gland dimensions; see the groove design guide. Its higher strength lets it resist extrusion a little better at the same hardness.
Send the part number and the quantity for HNBR
The AS568 dash number or the inside diameter and cross-section, the durometer, the quantity, the medium and temperature, and any specification the print names. A Conquest representative replies.
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