- Family
- NBR (nitrile)
- Standard range
- -34 C to 100 C (Parker® O-Ring Handbook ORD 5700)
- Special grades
- to -57 C, to 121 C
- Durometers
- By compound; the compound datasheet states the hardness
- Standards
- ASTM D1418 NBR; ASTM D2000 BF/BG/BK; MIL-PRF-25732, AMS-P-83461, AMS-P-5510, AMS-P-5315
- 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.
Nitrile O-rings (NBR, also sold as Buna-N) are the industrial default for petroleum oils, greases, hydraulic fluids and water at everyday temperatures, rated by the Parker O-Ring Handbook (ORD 5700) from -34 C (-29 F) to 100 C (212 F), with low-temperature compounds to -57 C and short-term service to 121 C. Conquest supplies nitrile O-rings in every AS568 and metric size across the full hardness range, including compounds made to the hydraulic and fuel-system specifications by listed manufacturers.
Nitrile O-ring specifications
| Property | Value | Source |
|---|---|---|
| Continuous service temperature | -34 C to 100 C (-29 F to 212 F); low-temperature compounds to -57 C; short term to 121 C | Parker ORD 5700 |
| Acrylonitrile content | Low, medium and high grades: more acrylonitrile means more oil resistance and less cold flexibility | General practice |
| Material designation | NBR under ASTM D1418; ASTM D2000 type-class BF, BG and BK line callouts | ASTM D2000 |
| Hydraulic specifications | MIL-PRF-25732 (MS28775, now AS28775; DLA qualified products list); AMS-P-83461 (M83461/1); AMS-P-5510 (MS28778 boss gaskets, 90 A) | DLA ASSIST record, read 2026-09-24 |
| Fuel specifications | MIL-P-5315 and AMS-P-5315 (MS29512, MS29513) | DLA ASSIST and SAE Mobilus records, read 2026-09-24 |
| Compliance available | FDA 21 CFR 177.2600 compliant nitrile on specific compounds for oil-contact food machinery | Compound datasheets |
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.
Where nitrile O-rings work, and where they fail
| Medium or condition | Verdict | Note (Parker O-Ring Handbook ORD 5700) |
|---|---|---|
| Hydraulic oil, engine oil, grease | Excellent | The core application; the standard rod and piston seal |
| Gasoline and diesel | Good | High-acrylonitrile grades; aromatics swell it more |
| Water, glycol-water coolant | Good | Moderate temperature |
| Dilute acids and alkalis | Acceptable | EPDM for hot or stronger solutions |
| Ozone, sunlight, outdoor service | Not recommended | Plain nitrile cracks; HNBR, EPDM or FKM |
| Ketones, chlorinated solvents, aromatics | Not recommended | EPDM for ketones; FKM for solvents |
| Steam, glycol brake fluid | Not recommended | EPDM |
Where nitrile fits
Nitrile fits oil and fuel service at everyday temperatures, indoors, where cost matters. We stock every AS568 size. The usual next families are HNBR for ozone or heat to 149 C, Viton® above that or for aromatic fuels, and EPDM for water, steam and brake fluid. The Buna-N O-ring guide covers the material in depth.
Sources: 21 CFR 177.2600; AMS-P-5315; AMS-P-5510; AMS-P-83461; AS28775; AS568; ASTM D1418; ASTM D2000; ISO 3601; MIL-P-5315; MIL-PRF-25732; MS28775; MS28778; MS29512; MS29513; 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
Is nitrile the same as Buna-N?
Yes. NBR is the ASTM designation, nitrile the common name, Buna-N the old trade name; the Buna-N page covers the same material under that name.
What is MS28775?
The nitrile hydraulic O-ring part number under MIL-PRF-25732, still ordered daily; parts are made by manufacturers on the DLA qualified products list. See the mil-spec chart.
Which durometer?
70 A for general service, 90 A for boss gaskets and high pressure. See the durometer guide.
Send the part number and the quantity for Nitrile
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.
Request a quote