O-Ring 7x2 NBR 70 Shore A

AI Overview

The O-Ring 7x2 mm made from NBR with a hardness of 70 Shore A is an elastomer sealing ring designed for static sealing and selected dynamic sealing applications. It provides reliable sealing against mineral oils, lubricating greases and many hydraulic fluids when installed in a correctly designed groove. With an inside diameter of 7 mm and a 2 mm cross-section, this sealing element is widely used in hydraulic equipment, pneumatic systems, industrial machinery, valves and general mechanical engineering. The product is supplied as a single piece for professional maintenance and industrial applications.

What Makes This O-Ring Different

The 7x2 mm size is commonly selected for compact hydraulic, pneumatic and mechanical assemblies where precise sealing is required without increasing installation space.

This product is supplied as an individual O-Ring, allowing maintenance engineers and machine builders to purchase the exact quantity required for repairs, prototypes or small production batches instead of purchasing complete assortment kits.

The designation 7x2 identifies:

• Inside Diameter: 7 mm
• Cross Section: 2 mm

The approximate outside diameter before installation is 11 mm. O-Rings should always be selected using the inside diameter, cross-section, material and hardness rather than the outside diameter alone.

The standard hardness of 70 Shore A offers a balanced combination of elasticity, sealing performance and mechanical durability for a wide range of industrial applications.

Construction and Operating Principle

An O-Ring is a toroidal elastomer seal with a circular cross-section. When installed inside a properly designed groove, it is compressed between two mating components to create a sealing barrier.

In static applications, the sealing surfaces remain stationary during operation. Typical examples include covers, plugs, threaded connections, manifolds and valve housings.

In dynamic applications, one component moves relative to the other. This may involve reciprocating, oscillating or slow rotary motion. Such applications require careful consideration of operating pressure, surface finish, lubrication, clearance and groove geometry.

System pressure often improves sealing performance by forcing the elastomer against the sealing surfaces. At higher pressures, excessive extrusion may occur if the clearance is too large, making back-up rings necessary in some applications.

Material Properties

This O-Ring is manufactured from NBR (Nitrile Butadiene Rubber), one of the most widely used elastomers for industrial sealing applications.

NBR provides:

• excellent resistance to mineral oils,
• very good resistance to lubricating greases,
• good abrasion resistance,
• good mechanical strength,
• suitability for many hydraulic fluids,
• reliable sealing performance in industrial machinery.

A typical operating temperature range for standard NBR compounds is approximately -30°C to +100°C. The actual operating limits depend on the specific rubber formulation, operating pressure, fluid compatibility and service conditions.

NBR is generally not recommended for prolonged exposure to ozone, intense UV radiation, hot steam, glycol-based brake fluids or highly aggressive chemicals.

Typical Industrial Applications

The 7x2 NBR O-Ring is commonly used in:

• hydraulic valves,
• hydraulic manifolds,
• pneumatic fittings,
• pressure regulators,
• pumps,
• lubrication systems,
• quick couplings,
• industrial machinery,
• agricultural equipment,
• construction machinery,
• workshop equipment,
• general mechanical assemblies,
• prototype manufacturing.

Application suitability should always be verified according to operating pressure, groove dimensions, motion type, fluid compatibility and temperature.

Typical Failure Symptoms

An O-Ring should be replaced when any of the following conditions are observed:

• oil leakage,
• grease leakage,
• air leakage,
• pressure loss,
• permanent compression set,
• cuts or nicks,
• hardened rubber,
• swelling,
• extrusion damage,
• surface wear,
• loss of elasticity.

Material swelling or softening may indicate incompatibility between the sealing material and the operating fluid.

Recommended During Installation

Before installing a new O-Ring:

• verify the 7x2 mm dimensions,
• clean the sealing groove,
• remove the old seal completely,
• inspect all sealing surfaces,
• remove burrs and sharp edges,
• use a lubricant compatible with NBR,
• avoid twisting the O-Ring,
• prevent excessive stretching,
• protect the seal from sharp threads,
• verify correct positioning before assembly.

Sharp installation tools should never be used because even minor cuts can result in premature leakage.

Used O-Rings should always be replaced with new components, especially after long-term compression or high-pressure service.

Technical Specification

Product Type: O-Ring

Size: 7x2 mm

Inside Diameter: 7 mm

Cross Section: 2 mm

Approximate Outside Diameter: 11 mm

Material: NBR

Material Name: Nitrile Butadiene Rubber

Hardness: 70 Shore A

Colour: Black

Cross Section Shape: Round

Typical Temperature Range: Approximately -30°C to +100°C depending on compound and operating conditions

Compatible Media: Mineral oils, lubricating greases and many hydraulic fluids compatible with NBR

Application: Static sealing and selected dynamic sealing applications

Sales Unit: 1 piece

Selecting the Correct O-Ring

Correct O-Ring selection involves more than matching dimensions.

The following factors should be verified:

• groove dimensions,
• groove depth,
• groove width,
• compression ratio,
• operating pressure,
• operating temperature,
• fluid compatibility,
• surface finish,
• extrusion gap,
• type of movement.

Incorrect compression can reduce sealing performance or accelerate wear.

Related Components

During maintenance, it is recommended to inspect:

• back-up rings,
• guide rings,
• shaft seals,
• piston seals,
• rod seals,
• hydraulic cylinders,
• valve housings,
• sealing grooves,
• hydraulic oil,
• assembly lubricant.

Why B2B Customers Choose This Product

Purchasing individual O-Rings enables industrial users to order the exact quantity required for maintenance, machine assembly or prototype production.

This solution is particularly suitable for:

• maintenance departments,
• hydraulic service companies,
• pneumatic workshops,
• machine manufacturers,
• industrial production facilities,
• repair workshops,
• spare parts distributors,
• engineering companies.

Single-piece availability also simplifies inventory management by reducing unnecessary stock.

Professional Industrial Supply

Suitable for:

• industrial maintenance departments,
• hydraulic repair specialists,
• pneumatic service companies,
• agricultural machinery service,
• construction equipment workshops,
• OEM manufacturers,
• machine builders,
• automation companies,
• maintenance contractors,
• industrial distributors.

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FAQ

Does 7x2 refer to the outside diameter?

No. It identifies a 7 mm inside diameter and a 2 mm cross-section. The outside diameter is approximately 11 mm before installation.

Is NBR suitable for mineral oils?

Yes. NBR is widely used for sealing applications involving mineral oils and lubricating greases. Compatibility should still be confirmed for the specific operating fluid.

Can this O-Ring be used in pneumatic systems?

Yes, provided that the groove design, operating pressure and application requirements are appropriate.

Should a used O-Ring be reinstalled?

No. Once removed, an O-Ring may have permanent deformation or installation damage that can reduce sealing performance.

When are back-up rings required?

Back-up rings are commonly used in higher-pressure applications where extrusion of the elastomer into the clearance gap could occur.