- 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
- 40 to 90 Shore A across the nitrile compounds Parker's handbook catalogues (Table 8-5); 70 A is its stock grade (N0674-70 kit, page 3-6); for boss seals Parker kits a 90 A tube-fitting set (N1490-90, page 3-6), and its AMS-P-5510 boss-gasket compound is N0507-90, 85 to 95 A (page 8-5)
- Standards
- ASTM D1418 NBR; 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, 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 and fuel resistance, at some cost to elasticity and compression set resistance | Parker ORD 5700 section 2.2.1, read 2026-09-25 |
| Material designation | NBR under ASTM D1418 | ASTM naming |
| Hydraulic specifications | MIL-PRF-25732, inactive; its MS28775 part standard is cancelled and superseded by SAE AS28775; AMS-P-83461 (M83461/1); AMS-P-5510 (MS28778 boss gaskets, 90 A) | DLA ASSIST record, read 2026-09-24 |
| Fuel specifications | AMS-P-5315 (current revision C), successor to the cancelled MIL-P-5315 (MS29512, MS29513) | DLA ASSIST and SAE Mobilus records, read 2026-09-24 |
Sizes and forms we supply
Every AS568 size, the general-purpose dash sizes and the boss-seal sizes alike, 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 rates better in dilute acids and alkalis |
| 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: AMS-P-5315; AMS-P-5510; AMS-P-83461; AS28775; AS568; ASTM D1418; ISO 3601; MIL-P-5315; MIL-PRF-25732; MS28775; MS28778; MS29512; MS29513; ORD 5700; Parker O-Ring Handbook; SAE Mobilus current-revision records (AMS-P-5315C), read 2026-09-27; Parker O-Ring Handbook ORD 5700, hardness guidance (page 2-10), stock O-ring kits (page 3-6) and Table 8-5 compound hardness, read 2026-09-25; Table 8-4 (page 8-5), read 2026-09-24; DLA ASSIST records for MIL-PRF-25732 (read 2026-09-24) and MS28775 (read 2026-09-25); Parker O-Ring Handbook ORD 5700, section VII fluid ratings, read 2026-09-25.
Parker is a trademark of Parker Hannifin Corporation. Viton is a trademark of The Chemours Company. No affiliation with or endorsement by either trademark owner is implied.
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. DLA ASSIST lists MS28775 as cancelled in 2000 and superseded by SAE AS28775, and MIL-PRF-25732 itself as inactive. See the mil-spec chart.
Which durometer?
70 A for general service, 90 A for boss gaskets and high pressure. See the durometer guide.
Orders are handled under Conquest Seal's AS9100D quality management system, whose certificate scope includes distribution.
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. Quotes answered within one business day. A person answers (714) 632-9830, Pacific business hours.
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