O-Rings

O-Rings are circular elastomeric seals with a round cross-section, widely used to prevent fluid or gas leakage between mating components. Their simple design, compact size and broad range of material options make them one of the most commonly used sealing components in industrial equipment.

O-Rings are used in pumps, valves, hydraulic and pneumatic systems, piping connections, compressors and various types of industrial machinery. They can provide reliable sealing in static applications and selected dynamic applications when the material, groove dimensions and operating conditions are properly matched.

O-Ring Material Options

NBR (Nitrile Rubber)

NBR is commonly used for sealing applications involving petroleum-based oils, hydraulic fluids and lubricants. It offers a practical balance of oil resistance, mechanical properties and cost for many industrial applications.

EPDM (Ethylene Propylene Diene Rubber)

EPDM is frequently used in water systems, selected aqueous chemicals and applications exposed to weathering or ozone. It is generally unsuitable for petroleum oils and hydrocarbon fuels.

FKM (Fluoroelastomer)

FKM is used in applications involving many oils, fuels and chemicals, including selected elevated-temperature environments. Compatibility depends on the specific compound and operating medium.

Silicone Rubber (VMQ)

Silicone O-Rings are valued for their flexibility over a broad temperature range. They are commonly selected for static sealing applications, although their abrasion and tear resistance may limit use in demanding dynamic conditions.

HNBR (Hydrogenated Nitrile Rubber)

HNBR provides improved heat, ozone and aging resistance compared with conventional NBR in many formulations. It is used in selected hydraulic, automotive and industrial sealing applications.

Standard Sizes & Dimensions

O-Rings are generally specified by two dimensions: inside diameter (ID) and cross-section diameter (CS).

Common size systems include:

• Metric Sizes: Specified in millimeters for a wide range of industrial equipment.

• AS568 Sizes: Standardized inch-based O-Ring sizes widely used in North American equipment.

• JIS Sizes: Japanese Industrial Standard size series used in various hydraulic, pneumatic and industrial applications.

Correct sizing is essential for sealing performance. The O-Ring dimensions must be compatible with the installation groove, compression requirements and operating conditions.

Static & Dynamic Sealing Applications

Static Sealing

O-Rings are widely used between stationary mating surfaces, including flange connections, equipment covers, valve bodies and fittings.

Reciprocating Sealing

In suitable hydraulic and pneumatic applications, O-Rings can be used to seal components moving back and forth. Material selection, lubrication, surface finish and groove design are important for controlling friction and wear.

Rotary Sealing

O-Rings can also be used in certain low-speed rotary applications. However, they are not automatically suitable for continuous or high-speed shaft rotation, where specialized rotary seals may be required.

Industrial Applications

Common applications include:

• Hydraulic and pneumatic equipment

• Pumps, valves and fittings

• Industrial piping connections

• Compressors and machinery

• Water treatment equipment

• Automotive and industrial components

• Equipment maintenance and replacement parts

Standard & Custom O-Rings

CORA SEALS supplies O-Ring options for industrial distributors, equipment manufacturers, maintenance contractors and spare parts buyers.

Standard metric, AS568 and JIS sizes can be sourced in different elastomer materials. Custom dimensions, hardness requirements and compound specifications can also be reviewed according to drawings, samples or technical requirements.

Request a Quote

Please provide the required inside diameter, cross-section diameter, material, hardness and quantity.

For replacement applications, existing part numbers, drawings or samples can help confirm the correct specification. If the material is not known, include the operating medium, temperature, pressure and sealing application so the requirements can be reviewed before quotation.