Nitrile (Buna-N) O-Rings

Nitrile (Buna-N, NBR) is the most widely used elastomer in the seal industry. It offers excellent resistance to petroleum products, oils, and greases, with strong compression set and abrasion resistance — making it the default specification for hydraulic, pneumatic, and fuel-system O-rings unless temperature or chemical exposure pushes the application toward Viton or Fluorosilicone.

Durometer
40A to 90A
Highlight
Excellent oil/fuel resistance
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Properties of Nitrile / Buna-N o-rings

Cannon Gasket cuts Nitrile / Buna-N o-rings to your drawing in durometer and thickness specifications of 40A to 90A Shore hardness. Excellent resistance to petroleum oils, fuels, greases, hydraulic fluids, and water. Not recommended for ozone, ketones, or chlorinated solvents.

Nitrile / Buna-N tolerances and customization

Standard dimensional tolerances on Nitrile / Buna-N o-rings land around ±0.010" to ±0.015" on OD and ID, depending on material durometer and thickness. Tighter tolerances are available on selected grades. Cannon Gasket cuts Nitrile / Buna-N to custom profiles in-house and matches lead times to your production volume. PSA backing, pad printing, custom packaging, and kitting are all on the menu when you need them.

Manufacturing, finishing & stocking

Standard sizes: Standard AS568 O-ring sizes are available; see the AS568 O-Ring Size Chart for the full size reference. Custom cross-sections and inside diameters are cut to your specification.

Clean room: Cannon Gasket offers clean-environment stamping for medical, FDA, electronic, and scientific applications where a controlled level of particulate is required, with capabilities to meet ISO Class 10,000.

Stocking agreements: Blanket orders, VMI (vendor-managed inventory), JIT (just-in-time), and Kanban replenishment programs.

Pad printing: Pad print your part number, identification marking, or company name in a range of ink colors. Marking per customer specifications or MIL-STD-130.

Packaging: Parts are bagged and tagged in specified quantities and labeled with P/N or any required information. Capability to meet specific packaging and labeling requirements.

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Key Properties
  • Durometer: 40A – 90A
  • Excellent oil/fuel resistance
  • Good compression set
  • Cost-effective
  • AS568 standard sizes
Engineering Tools
Applications
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Frequently Asked Questions

Common Nitrile / Buna-N questions.

Are you ISO 9001 certified?
Yes, ISO 9001:2015 certified. Documented quality management covers incoming material verification, in-process inspection, calibrated measurement, final inspection, non-conformance handling, corrective action, and full lot traceability. AS9100-ready for aerospace, with MIL-spec and FDA 21 CFR 177.2600 / USP Class VI grades available on request.
Do you stock standard AS568 O-ring sizes?
Yes, all AS568 dash numbers in common compounds (Buna-N, Viton, Silicone, EPDM) are available. Our AS568 size-chart tool on /tools/o-ring-size-chart/ has the full dimensional reference. Custom non-standard sizes quoted from drawing.
What is a lathe-cut O-ring?
A lathe-cut seal is turned from tube stock instead of molded. Square cross-section instead of round. Lower tooling cost and often better dimensional stability than molded O-rings at low-to-mid volume. See /lathe-cut-washers/ for details.
What is the difference between dynamic and static O-ring applications?
Static means the O-ring is compressed between non-moving surfaces (flange gasket, cap seal). Dynamic means at least one mating surface moves relative to the O-ring (piston seal, rotary shaft). Dynamic applications need a harder durometer, tighter clearances, and sometimes lubricated surfaces.
Why do O-rings fail?
Three big killers: abrasion from rough mating surfaces, chemical attack that swells or hardens the elastomer, and extrusion from too-large clearance gaps under pressure. Our Common Reasons O-Rings Fail article walks through diagnostic signs.
How fast do you return a quote?
Most RFQs come back within one business day. Simple profile updates to an existing tool quote same-day. Send a drawing, DXF, or competing part number and our engineering team reviews material, tolerance, and volume before pricing.
What is the minimum order quantity?
Minimums depend on the part and material. We cut prototype and first-article quantities for engineering evaluation, then scale up to production volumes from the same tooling. For high-volume programs we run JIT, VMI, and Kanban replenishment out of Fontana, California.
What should I send with an RFQ?
Ideal: a drawing or DXF, material spec (or compound family), estimated annual volume, and any regulatory callouts (FDA, USP Class VI, AS9100, MIL-spec). If you only have a sample or a part number from a competing supplier, send that and we will reverse-engineer the spec before quoting.
What are typical lead times?
Prototype and first-article parts usually ship in 5-10 business days. Production runs from existing tooling are 2-3 weeks depending on volume and material lead time. Rush and expedite options available on a case-by-case basis.
Need custom Nitrile / Buna-N O-rings?
Standard AS568 sizes and custom configurations available.
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ISO 9001 CertifiedAS9100-ReadyMIL-Spec CompatibleFDA / USP Class VIEst. 1971ISO 9001 CertifiedAS9100-ReadyMIL-Spec CompatibleFDA / USP Class VIEst. 1971ISO 9001 CertifiedAS9100-ReadyMIL-Spec CompatibleFDA / USP Class VIEst. 1971ISO 9001 CertifiedAS9100-ReadyMIL-Spec CompatibleFDA / USP Class VIEst. 1971