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Black NBR O-rings are compression molded with a 3.2mm cord and outer diameters from 9mm to 400mm, offering good oil resistance and waterproof sealing performance.
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Full-size customization is available; cord diameter, outer diameter and hardness can be confirmed to drawing or sample for hydraulic, pneumatic and pipeline sealing applications.
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Factory supply includes sample testing and bulk orders; NBR compound and dimensional tolerance should be confirmed against the actual medium, temperature and compression ratio.
NBR O-Rings
Oil Resistant Waterproof NBR O-Ring 9mm to 400mm Factory
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Our NBR O Rings (Nitrile Rubber O-Rings) are high-quality industrial rubber seals designed for reliable sealing performance in hydraulic, pneumatic, automotive, and industrial applications. Made from durable nitrile butadiene rubber, these oil-resistant O-rings offer excellent resistance to mineral oils, fuels, grease, and water. With good elasticity, compression recovery, and wear resistance, NBR rubber O-rings are suitable for both static and dynamic sealing applications under moderate temperature conditions.
As a professional NBR O-ring manufacturer and supplier, we offer standard NBR O-ring sizes in stock, as well as custom rubber O-rings in various inner diameters, cross-sections, hardness levels, and colors. Our custom NBR O-rings, nitrile rubber seals, waterproof O-rings, and hydraulic sealing rings provide cost-effective sealing solutions for pumps, valves, cylinders, pipelines, automotive systems, and pneumatic equipment. OEM and ODM services are available to meet different industrial sealing requirements.
NBR O- Ring Technical Table
Item Specification Material Name NBR (Nitrile Butadiene Rubber) O Ring Seals Common Hardness Shore A 40 – 90 (Standard: Shore A 70) Operating Temperature Range -40℃ to 120℃ Low Temperature Resistance Excellent flexibility at low temperature High Temperature Resistance Stable performance under continuous 100℃ working condition Oil Resistance Excellent resistance to mineral oil, engine oil, hydraulic oil and grease Water Resistance Good waterproof and anti-leakage performance Abrasion Resistance Good wear resistance for dynamic sealing applications Compression Set Low compression deformation, long sealing stability Weather Aging Resistance Moderate aging resistance, not suitable for long-term outdoor UV exposure Chemical Compatibility Resistant to oil, water, fuel and common lubricants Incompatible Media Strong oxidants, ketones, esters, strong solvents Sealing Type Static sealing & dynamic sealing Standard Sizes Metric sizes / AS568 inch standard sizes Customization Custom hardness, size and color available Environmental Standard RoHS compliant Main Applications Hydraulic systems, pneumatic systems, pumps, valves, compressors, automotive parts, agricultural machinery, construction machinery, general industrial equipment Feature Most cost-effective, widely used, reliable industrial rubber sealing ring How to measure the O-Rings Size ?
1.Do not measure O-rings with a ruler.
2.Use a caliper to accurately get ID, OD and cross-section CS.
3. Rubber O-rings deform easily. Accurate measurement ensures proper fit and prevents leakage.
O-Ring ID size tolerance for GB/T 3452.1-2005 standard
Standard d₁(mm) G-Series Tolerance ±(mm) A-Series Tolerance ±(mm) 1.8~5.0 0.13 0.08 5.3~8.5 0.16~0.17 0.09~0.10 8.7~12.5 0.18~0.20 0.10~0.12 13.2~18.0 0.21~0.25 0.12~0.14 19.0~26.5 0.25~0.30 0.14~0.17 27.3~37.5 0.31~0.34 0.17~0.20 38.7~50.0 0.34~0.40 0.20~0.23 51.5~67.0 0.41~0.48 0.23~0.27 69.0~90.0 0.49~0.60 0.27~0.33 92.5~125 0.61~0.78 0.33~0.42 132~180 0.82~1.02 0.42~0.54 190~250 1.06~1.34 0.54~0.70 258~355 1.37~1.82 0.70~0.95 365~500 1.86~2.48 0.95~1.30 Remark:
- G series: General purpose O-rings, looser tolerance for normal hydraulic & pneumatic applications
- A series: Aerospace grade O-rings, tighter ID tolerance for high-precision, high-reliability sealing
Cross-section tolerance:
1.8:±0.08mm 2.65:±0.09mm 3.55:±0.10mm 5.3:±0.13mm 7.0:±0.15 mm.We have strict size inspection for each order .Tight tolerance control guarantees consistent performance batch after batch.
Our NBR O-Rings Advantages
Our NBR nitrile rubber O-rings offer good rebound resilience, recovering quickly after repeated compression and under dynamic sealing conditions to help maintain stable sealing performance.
Made from premium NBR nitrile rubber, offering oil resistance, wear resistance, good rebound resilience and reliable sealing performance for hydraulic, pneumatic and pipeline sealing applications.
Smooth surface finish with no burrs, helping reduce friction and leakage risk.
Application Areas of NBR O-Rings
NBR O-rings are mainly valued for oil resistance, wear resistance, good rebound resilience and reliable sealing. Typical applications include:
- Hydraulic systems: static and dynamic sealing at hydraulic cylinders, valves, pumps and pipe joints.
- Pneumatic systems: sealing for cylinders, pneumatic valves, air line fittings and pneumatic actuators.
- Automotive industry: oil-resistant sealing points in engines, gearboxes, fuel systems, lubrication circuits, brake systems and air-conditioning lines.
- Industrial pumps and valves: sealing for water pumps, oil pumps, chemical pumps (non-highly corrosive media), valves, flanges and pipe connections.
- Mechanical equipment: bearing end covers, reducers, gearboxes, compressors and rotating/reciprocating parts.
- Oil and fuel systems: sealing for mineral oil, lubricating oil, diesel, hydraulic oil and similar media; not recommended for aromatic hydrocarbons, ketones, esters or strongly oxidizing media.
- Plumbing and general industry: medium- and low-pressure sealing for water, air and neutral media; for outdoor applications requiring high weather and ozone resistance, use with caution or switch to EPDM or other suitable materials.
Selection Note: NBR typically serves from about -40°C to +100°C (short-term up to around 120°C). It has good oil resistance but limited resistance to ozone, weathering and polar solvents. For strong acids, strong alkalis, ketones, esters, aromatic hydrocarbons or long-term outdoor exposure, FKM, EPDM or other materials should be evaluated.
Common rubber O-rings (NBR ,EPDM,VMQ,FKM)
Brief Introduction:
This guide compares four common O-ring materials: FKM, VMQ, NBR and EPDM. FKM offers excellent heat and chemical resistance, making it suitable for fuels, oils and aggressive media. VMQ (silicone) provides a wide temperature range and good flexibility but limited oil resistance. NBR is the standard choice for oil and fuel sealing with good mechanical properties, while EPDM excels in water, steam and weather resistance but is not oil-resistant. Selecting the right material depends on the operating temperature, medium and sealing application.
Our factory Production equipment
We are equipped with complete production facilities including mixing machines, CNC machines, injection molding machines, cryogenic deflashing machines and post-curing ovens. In-house mold making and automated workflows boost efficiency to support fast order delivery.
Packing /Payment/Shipping service
- Package:We provide standard cartons, pallets and wooden cases. Custom packaging is available upon request to protect goods well for different shipments.
- Payment Methods:Multi-currency settlement (CNY, USD, EUR, etc.). Multiple payment options including T/T, PayPal. Local bank transfer is available for some countries for faster transactions.
- Delivery Method:We offer international express, air freight, sea freight and railway transport. You can also appoint your own forwarder for flexible delivery arrangements.
Our Supplied Rubber Seals
We manufacture a full range of sealing products: O-rings and X-rings in NBR, EPDM, FKM, FFKM, VMQ, HNBR; oil seals of various styles including TC, TG, VC, TB, TA, VB, SB, SA, VA, DC, HTC. We also supply ED seals, bonded seals, wiper seals, gaskets, washers, rubber balls, and custom special-shaped sealing profiles. Custom non-standard rubber seals are available to match your unique working conditions.
OEM and ODM Service
We support both OEM and ODM cooperation. Under OEM, customers provide drawings, samples, material and dimensional requirements, and we manufacture to specification with customer-branded packaging, suitable for orders with a clearly defined design. Under ODM, we can participate in material selection, compound adjustment, mold development, size and hardness design based on the customer's operating conditions, and provide private-label production, suitable for customers needing one-stop support from product development to mass production. Both models are available for custom rubber balls, O-rings and other rubber sealing parts, with lead time, tooling cost and MOQ confirmed per project.
FAQs-
What is the normal service temperature of NBR O-rings? Can they be used at 120°C for short periods?
NBR typically serves from about -40°C to +100°C, with short-term peaks up to around 120°C, but service life will be noticeably reduced. For long-term use above 100°C or in hot oil, consider a higher-temperature material such as FKM, and validate heat aging performance against the actual temperature, medium and compression ratio.
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What is the maximum size of molded parts you can produce?
Our 350-ton molding press supports large-size molding, with a maximum part dimension of 102” × 72” for oversized rubber and polyurethane components.
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What media are NBR O-rings resistant to, and which media are not recommended?
NBR has good resistance to mineral oils, lubricating oils, hydraulic oils, diesel, gasoline and many greases. It is not recommended for ketones (acetone, MEK), esters, aromatic hydrocarbons (benzene, toluene), strong acids, strong alkalis, strongly oxidizing media, or long-term ozone/outdoor exposure. For such media, consider FKM, EPDM, PTFE or other suitable materials.
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What is the common hardness of NBR O-rings, and how should hardness be selected?
70 Shore A is the most common hardness, with 50–90 Shore A generally available. Lower hardness can improve contact in low-pressure static sealing; higher hardness is preferred for high-pressure, dynamic sealing or extrusion-resistant applications, together with backup rings or adjusted groove clearance. Hardness tolerance is usually controlled at ±5 Shore A.
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What is the typical compression set of NBR O-rings?
Compression set depends on compound, hardness and test conditions. For a general-purpose 70 Shore A NBR, typical values under ASTM D395 at 70 h/100°C are about 20%–35%, and low-compression-set grades can be lower. Sealing applications should be validated against the actual compression ratio, temperature and time rather than judged by material grade alone.
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What standards apply to NBR O-ring dimensional tolerances, and how are non-standard sizes handled?
Common standards include GB/T 3452.1, ISO 3601-1 and AS568. Standard parts should be checked against the cord diameter and inside diameter tolerances in the applicable standard; for non-standard sizes, cord diameter, inside diameter tolerance and roundness requirements should be separately agreed in drawings or technical agreements. For incoming inspection, cord diameter tolerance should be controlled first because it directly affects compression and sealing performance.
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What should be noted during installation and storage of NBR O-rings?
Before installation, clean the groove and sealing surface, apply a lubricant compatible with NBR if needed, and avoid twisting, scratching or excessive stretching. Groove design should provide a static sealing compression ratio of about 15%–25% and a dynamic sealing compression ratio of about 10%–15%. Store in a dark, cool place away from ozone, motors and direct sunlight; keep original packaging unopened at room temperature and follow first-in, first-out.
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What are the common O-ring failure modes and how to identify them?
- Compression set: flattened cross-section and flat contact surfaces, from heat or excessive squeeze; - Extrusion (nibbling): ragged, tattered edges on the low-pressure side, from excessive clearance or pressure; - Spiral failure: 45° spiral cuts on the surface, common in long-stroke pistons when parts slide and roll simultaneously; - Abrasion: scratched/worn surfaces from rough mating surfaces or poor lubrication; - Chemical attack: swelling, cracking, or softening from incompatible media.
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