NBR is a copolymer of acrylonitrile (ACN) and butadiene, and ACN loading is the single number that swings its fluid resistance and low-temperature flexibility in opposite directions — 28–35% ACN for low-temperature sealing, 33–38% for general petroleum and hydraulic oil, 38–45% for high-ACN fuel-line and aromatic-fluid service, and 45–55% for extreme gasoline/alcohol-blend resistance [S2].
Across 2026 buying traffic, 32 industrial manufacturers list 161 NBR fitting SKUs on DirectIndustry [S1], while Made-in-China carries premium-grade NBR 3345 at USD 1,000–1,200/t MOQ 5 t [S3], Lanhua NBR 3305E at USD 2,170–2,260/t MOQ 1 t [S4], and white NBR sheet from RS PRO at 1.5 m × 1 m × 1.5 mm rated to 100 °C / 7 MPa [S8]. The reference buying lens, including selection criteria, ACN/hardness/temperature/fluid gates, is detailed in the NBR selection-criteria article at NBR Selection Criteria: ACN, Hardness, Temperature and Fluid Gates.
ACN Content Bands and What They Lock In
ACN is the master spec on any NBR datasheet, and SAE AMS3227G-2003 (Hot Oil and Coolant Resistant, Low Swell 55–65) is the most cited aerospace-grade NBR callout, with the standard itself covering sheet, strip, tubing, extrusions, and molded shapes in NBR [S2]. At 28–35% ACN, swelling in aliphatic oils rises, but TR-10 and low-temperature flexibility improve to roughly -40 °C, so the part is suitable for general hydraulic and gear-oil seals at sub-arctic sites. At 33–38% (the workhorse band), oil swell sits in the 0–15% range against ASTM IRM 903 at 100 °C × 70 h, and cold-flex drops to about -30 °C — the band most plant engineers default to for pumps, valves, and gearbox lip seals.
At 38–45% ACN, fuel permeability drops by roughly 30–50% versus 33% ACN grades, making these the default for EFI fuel lines, carburetor diaphragms, and small engine hose, exemplified by 1/4" NBR EFI fuel line hose at USD 14.28 with 128 units sold [S7]. Above 45% ACN, polar-fluid resistance is strong but low-temperature flexibility falls below -20 °C, and the compound is reserved for aromatic gasoline, alcohol-blend fuels, and aggressive chemicals. Hardness typically runs Shore A 50–90 across the bands, with 70 ± 5 being the most common gland-pack target.
Temperature, Pressure and Fluid Compatibility Window
Standard NBR is rated from about -30 °C to +110 °C continuous, with intermittent peaks near 120 °C; hydrogenated NBR (HNBR) extends that to roughly -40 °C / +150 °C, and peroxide-cured NBR tolerates higher hot-oil exposure than sulfur-cured grades [S2]. RS PRO's NBR sheet at 1.5 mm thickness is rated to 100 °C and 7 MPa, illustrating the practical pressure ceiling on thin-gauge NBR sheet goods [S8].
Fluid gates are the second decision: NBR is strong against petroleum oils, diesel, kerosene, glycol, water, and dilute acids/bases, but poor against ketones (acetone, MEK), esters, chlorinated hydrocarbons, brake fluid (DOT 3/4), strong acids, and ozone. Where DOT 3/4 brake fluid or ketones are present, switch to EPDM, FKM, or epdm-rubber; where dry-heat or food contact is required, switch to silicone-rubber despite a lower tensile envelope. For broad oil/heat compromise, see the Silicone vs FKM: Service Window, Chemical Resistance and Selection Logic reference.
Form Factor and Sizing Patterns
Buying NBR happens at four distinct form levels: raw gum (1–25 t MOQ), pre-compounded slab, finished sheet, and finished molded part. NBR 3345 premium cold-polymerisation gum is listed at USD 1,000–1,200/t with 5 t MOQ [S3], and Lanhua NBR 3305E at USD 2,170–2,260/t with 1 t MOQ, suitable for oil-resistant and wear-resistant molded goods [S4]. NBR sheet from Made-in-China sits at USD 0.40–1.58/m² depending on density and width, with MOQs of 25 m to 100 m², and 1.5 mm / 3 mm / 6 mm thicknesses dominate the catalog [S5].
Finished goods span O-rings (2 mm cross-section, OD 8–80 mm at roughly USD 1.45 per piece [S6]), fuel hose (1/4" ID at USD 14.28 per 1 m [S7]), and hydraulic/pneumatic fittings from 32 industrial suppliers [S1]. Cross-section tolerance for commodity O-rings is typically ±0.08 mm on small sizes, tighter to ±0.05 mm on AS568 premium grades. Buyers specifying against hydraulic cylinders should also reference gland geometry from the linear-guide or crossed-roller-guide side, since wipers and rod seals run in the same envelope as the bearing stack.
2026 Price Bands, MOQs and Sourcing Map
Raw NBR is a price-tiered market: USD 1,000–1,200/t for general-purpose 3345-class [S3], USD 2,170–2,260/t for specialty 3305E [S4], and NBR latex for dipping typically USD 1,400–1,900/t on long-term contracts. Sheet runs USD 0.40–1.58/m² [S5], and finished industrial O-rings in metric/AS568 sizes fall into a USD 0.05–2.00 per piece band depending on compound and lot size. Sourcing geography in 2026 still skews to China (Lanhua, Nanjing Hairui, Anhui Huales, Tai'an Xinrui), with Europe (RS PRO) and North America covering spec-critical aerospace and food-grade lots.
For a like-for-like read across elastomer families, the Silicone Rubber Price & Cost Guide 2026 breaks down grade/hardness/MOQ levers on the silicone side, and the broader industrial-rubber reference gives material-by-material comparison context. Lead times in 2026 cluster at 7–15 days for stocked sheet, 25–35 days for custom-compounded pre-forms, and 45–75 days for first-article molded NBR parts.
Verification, Standards and Failure-Mode Watch-List
Three specs to lock before issuing a PO: ACN percentage (tied to fluid service), Shore A hardness (gland-pack fit), and compression set after 70 h at the rated temperature. SAE AMS3227G is the canonical aerospace callout for hot-oil and coolant-resistant NBR with low swell (55–65 Shore A) [S2]. For automotive fuel systems, buyers typically pair SAE J30 with an R-class fuel-resistance rating; for food and dairy, FDA 21 CFR 177.2600 or BfR XXI categories are the gating compliance marks. The general-purpose nitrile-rubber entry covers grade-by-grade compound design.
Common failure modes are well mapped: extrusion gaps over 0.15 mm on rod seals, compression set above 25% after hot-oil aging, and explosive decompression in high-pressure gas NBR parts (a known weakness vs FKM). Mitigations are hardness bump to 85–90 Shore A, back-up rings in PTFE or PE, and HNBR upgrade when continuous dry-heat exposure exceeds 110 °C. The internal encyclopedia pages on linear-guide and crossed-roller-guide show how seal geometry is sized to bearing envelope in real machine-tool and robotics builds. Next, watch Q3 2026 RS PRO and Lanhua price-list revisions for any post-tariff adjustments on NBR 3305E and 3345 grades, and the next DirectIndustry supplier-count refresh for NBR fitting category depth.