A Guide to the Different Sizes and Standards of Parker O-Rings

Parker O-Rings are essential components used in various industries to create seals and prevent leaks. They are commonly found in hydraulic and pneumatic systems, automotive applications, and many other machinery and equipment. 

What Are O-Rings?

O-Rings are circular seals made from elastomeric materials. They are designed to fit into a groove and compress when two surfaces are joined. This compression creates a tight seal that prevents fluids or gases from leaking. O-Rings come in various sizes, materials, and standards to suit different applications and environments.

Importance of Size and Standards

Choosing the correct size and standard for an O-Ring is vital for ensuring effective sealing. The wrong size can lead to leaks, equipment failure, and increased maintenance costs. Parker O-Rings are designed to meet specific industry standards, making it easier to find the right fit for your needs.

Common Sizes of Parker O-Rings

Parker offers a wide range of O-Ring sizes to accommodate various applications. The most common sizes include:

• AS568 Standard Sizes

The AS568 standard is a widely recognized sizing system for O-Rings in the United States. It includes a series of sizes designated by a three-digit code (e.g., AS568-001, AS568-002, etc.). The codes indicate the inner diameter and the cross-sectional diameter.

• Cross-Sectional Diameter

This is the thickness of the O-Ring. Common cross-sectional sizes include 0.070 inches, 0.103 inches, and 0.139 inches.

• Inner Diameter

This is the diameter of the hole that the O-Ring fits into. For example, an AS568-001 O-Ring has an inner diameter of 0.139 inches.

• Metric Sizes

In addition to AS568 sizes, Parker also provides metric O-Ring sizes. These are measured in millimeters and are often used in applications outside the United States. Common metric sizes include 2.0 mm, 3.0 mm, and 4.0 mm for cross-sectional diameters, with various inner diameters to match.

• Custom Sizes

If standard sizes do not fit your application, Parker offers custom O-Ring sizes. These can be tailored to meet specific requirements, ensuring a proper fit and seal.

O-Ring Material Standards

Parker O-Rings are made from various materials, each designed to perform in different environments. Some common materials include:

• Nitrile (Buna-N)

This is one of the most common O-Ring materials. It offers good resistance to oils, fuels, and greases. It is suitable for applications in automotive and hydraulic systems.

• Fluoroelastomer (Viton)

Viton O-Rings are known for their high resistance to heat, chemicals, and weathering. They are ideal for applications in harsh environments, such as aerospace and chemical processing.

• Silicone

Silicone O-Rings offer excellent flexibility and temperature resistance. They are commonly used in applications requiring low-temperature performance or exposure to food.

• EPDM

Ethylene Propylene Diene Monomer (EPDM) O-Rings are highly resistant to water, steam, and weathering. They are suitable for outdoor applications and in environments exposed to harsh conditions.

Selecting the Right Parker O-Ring

When selecting the right Parker O-Ring for your application, consider the following factors:

• Size

Choose an O-Ring that matches the inner diameter and cross-sectional diameter required for your application. Refer to the AS568 or ISO 3601 standards for guidance.

• Material

Select a material that suits the fluids or gases the O-Ring will encounter. Consider temperature, pressure, and chemical compatibility.

• Environmental Conditions

Consider the operating environment. Will the O-Ring be exposed to extreme temperatures, chemicals, or outdoor elements? Choose a material that can withstand these conditions.

• Application Type

Think about the specific application. Different industries may have different requirements for sealing performance. Make sure to choose an O-Ring that meets these needs.

Maintenance and Replacement

To ensure optimal performance, regularly check O-Rings for wear and damage. Signs of failure may include cracking, swelling, or reduced elasticity. Replace O-Rings as needed to prevent leaks and maintain system integrity.

Conclusion

Parker O-Rings are crucial components in various applications, providing reliable sealing solutions. Understanding the different sizes, materials, and standards of O-Rings is essential for selecting the right seal for your needs. By considering factors such as size, material, and environmental conditions, you can ensure optimal performance and reliability in your systems.