O-ring Cord 20 mm NBR - Round Nitrile Rubber Sealing Cord

Technical Specification

The 20 mm dimension refers to the nominal diameter of the cord cross-section, not the inside diameter of a finished O-ring.

The NBR designation identifies the elastomer family but does not establish the specific compound formulation, Shore A hardness, dimensional tolerance, or permissible operating temperature.

What Does O-ring Cord 20 mm NBR Mean?

Unlike a finished O-ring, sealing cord does not have a predetermined closed circumference.

The required length can be selected according to the sealing arrangement. Where a closed ring is necessary, the cord ends must be joined using a method compatible with the rubber compound and operating conditions.

NBR Material Properties

NBR is a synthetic elastomer widely used in industrial sealing technology because of its resistance to many mineral oils, lubricating greases, and selected technical fluids.

General characteristics of NBR include:

• Good resistance to many mineral oils and greases.

• Suitability for selected hydraulic and pneumatic sealing systems.

• Elastic deformation that generates sealing contact pressure.

• Mechanical properties dependent on compound formulation and hardness.

• Limited resistance to ozone and prolonged atmospheric exposure compared with elastomers specifically designed for these conditions.

Not all NBR compounds provide identical chemical resistance or mechanical performance.

Compatibility must be assessed for the actual fluid, operating temperature, exposure duration, and rubber formulation.

Construction and Operating Principle

O-ring Cord 20 mm NBR has a solid circular cross-section with a nominal diameter of 20 mm.

When installed in a correctly designed sealing groove, the elastomer undergoes controlled compression. This generates contact pressure between the sealing profile and the mating surfaces, helping prevent leakage.

Sealing performance depends on:

• Cross-section diameter and dimensional tolerance.

• Groove dimensions and geometry.

• Elastomer compression.

• NBR compound hardness.

• Operating pressure and temperature.

• Surface finish of mating components.

• Chemical compatibility with the sealed medium.

• Joint integrity if the cord is used to form a closed ring.

A 20 mm cross-section requires an appropriately designed groove. Insufficient compression may cause leakage, while excessive compression can accelerate material deterioration.

NBR O-ring Cord vs. a Finished NBR O-ring

A sealing ring manufactured from joined cord is not automatically equivalent to a one-piece moulded O-ring.

The joint may have different tensile strength, elasticity, and sealing characteristics from the rest of the profile.

This distinction is particularly important in applications involving pressure, movement, or repeated mechanical loading.

Selection and Interchangeability

Before selecting O-ring Cord 20 mm NBR, verify:

1. Nominal cross-section diameter of 20 mm and its tolerance.

2. Shore A hardness of the specific NBR compound.

3. Chemical compatibility with the sealed medium.

4. Operating pressure and temperature.

5. Groove geometry and required compression.

6. Required cord length.

7. Joining method if a closed ring is necessary.

8. Static or dynamic sealing conditions.

NBR cords with identical cross-section diameters but different hardness values or compound formulations are not necessarily interchangeable.

Replacing a 20 mm cord with a different cross-section diameter also requires reassessment of groove geometry and compression.

Applications

O-ring Cord 20 mm NBR may be considered for appropriately designed:

• Static seals in industrial housings and covers.

• Mechanical joints requiring elastomer sealing.

• Systems involving compatible mineral oils and greases.

• Selected hydraulic installations, subject to pressure and material verification.

• Sealing rings with non-standard circumferences.

• Industrial maintenance and repair operations.

These are potential applications based on the properties of NBR and the cord geometry, not confirmed OEM applications of a particular manufacturer's product.

Standard NBR compounds are generally unsuitable for prolonged ozone exposure and may be incompatible with ketones, aromatic solvents, and glycol-based brake fluids. Chemical compatibility must be verified for the specific compound and operating conditions.

Calculating Cord Length for a Custom O-ring

For an ideal circular sealing ring, the theoretical cord length measured along the centreline of the cross-section can be calculated as:

Where:

• L = theoretical cord length in mm.

• ID = intended inside diameter of the finished ring in mm.

• d = cord cross-section diameter, 20 mm.

For example, for a ring with an intended inside diameter of 200 mm:

This is a theoretical geometric calculation. Actual cutting length may require adjustment depending on the joining method, elastomer deformation, and installation requirements.

Alternative Designations and Search References

Natural descriptive variations include:

• O-ring Cord 20 mm NBR

• NBR O-ring Cord 20 mm

• Round NBR Sealing Cord 20 mm

• Nitrile Rubber Cord 20 mm

• Round NBR Rubber Cord 20 mm

• NBR Sealing Profile 20 mm

These are alternative descriptive designations, not verified manufacturer part numbers or OEM references.

No confirmed manufacturer-specific cross-references have been established.

Installation and Storage

Before installation, clean the sealing groove and mating surfaces. Inspect the cord for cuts, flattening, deformation, or other damage.

The cord should be cut using a suitable tool that produces the required end geometry. If a closed sealing ring is needed, the joining method must be compatible with the specific NBR compound and the application's mechanical requirements.

During installation:

• Avoid twisting the sealing profile.

• Prevent excessive stretching.

• Protect the cord from sharp edges.

• Position the material evenly inside the groove.

• Use installation aids compatible with NBR.

• Verify the joint before placing the seal into service.

Store the cord in clean, dry conditions, away from excessive heat, direct sunlight, ultraviolet radiation, and ozone sources.

FAQ - Frequently Asked Questions

What is the diameter of O-ring Cord 20 mm NBR?

The nominal diameter of its circular cross-section is 20 mm. This does not indicate the inside diameter of a finished O-ring.

What does NBR mean?

NBR stands for nitrile butadiene rubber, a synthetic elastomer commonly used in industrial seals because of its resistance to many mineral oils and greases.

Is O-ring Cord 20 mm NBR oil-resistant?

NBR generally provides good resistance to many mineral oils and lubricating greases. Compatibility with a specific oil depends on the compound formulation, temperature, and operating conditions.

What is the Shore A hardness of O-ring Cord 20 mm NBR?

The hardness has not been specified. The NBR designation alone does not establish a Shore A hardness of 70, 80, or 90.

Can O-ring Cord 20 mm NBR be used to manufacture a closed O-ring?

Yes, provided a suitable joining method is used and the resulting sealing ring meets the mechanical and sealing requirements of the application.

Can NBR O-ring cord be used in hydraulic systems?

It may be suitable for selected static hydraulic seals involving compatible fluids. Operating pressure, temperature, groove geometry, and joint strength must be verified.

Is O-ring Cord 20 mm NBR weather-resistant?

Standard NBR compounds have limited resistance to ozone and prolonged atmospheric ageing. Suitability for outdoor exposure should be assessed using the specific material specification.

Can NBR O-ring cord be replaced with EPDM or FKM cord?

Not automatically. These elastomers differ in chemical resistance, temperature performance, and mechanical properties. Identical cross-section dimensions do not guarantee interchangeability.

O-ring Cord 20 mm NBR - Key Technical Information

O-ring Cord 20 mm NBR is a solid, round sealing profile made from nitrile butadiene rubber, with a nominal cross-section diameter of 20 mm. It is primarily used to prepare static seals of customized lengths. NBR offers resistance to many mineral oils and greases. Correct selection requires verification of hardness, dimensional tolerance, chemical compatibility, and operating conditions.

NBR O-ring Cords at simmering.pl

simmering.pl is a specialist B2B industrial trading platform supplying NBR O-ring cords, O-rings, oil seals, bearings, and technical sealing components to manufacturers, maintenance departments, engineers, and industrial procurement professionals.

Based in Lublin, Poland, simmering.pl supports worldwide shipping from stock in Poland, subject to product availability and destination-specific shipping arrangements.