GMORS

Introduction

The O-Ring is a simple yet indispensable sealing component, widely used in industries such as hydraulics, pneumatics, automotive, aerospace, energy, and electronics. Its primary function is to be installed between two contact surfaces to form a seal and prevent the leakage of liquids or gases. Despite being just a small rubber ring, improper material selection may lead to hydraulic oil leakage, fuel leakage, or even compromise overall equipment safety and operational efficiency.

Different working conditions impose different requirements on O-Ring materials: high temperatures accelerate rubber aging, low temperatures may cause brittleness and cracking, contact with chemicals can lead to swelling or decomposition, while applications in the food and medical industries must comply with strict regulatory standards. Selecting the right material for each environment is the key to ensuring reliable sealing and extending service life. This article will break down the core principles of O-Ring material selection, compare common materials, provide application guidelines, address frequently asked questions, and introduce professional solutions from GMORS.

1. Core Principles of O-Ring Material Selection

Temperature Range

Temperature has a significant impact on O-Rings. High temperatures accelerate molecular chain breakdown, causing rubber to harden and lose elasticity; low temperatures may make rubber brittle and unable to recover its shape, leading to leakage. Different materials have different temperature resistance ranges—for example, NBR is suitable for -40°C to 100°C.

Media Compatibility

When O-Rings come into contact with hydraulic oil, fuel, solvents, gases, or food products, incompatibility may cause the material to absorb fluids, swell, harden, or crack. For instance, EPDM performs excellently in water and steam environments but deteriorates rapidly in oils.

Pressure and Mechanical Load

In static sealing, O-Rings barely move and mainly withstand pressure and chemical exposure, whereas dynamic sealing requires resistance to friction and wear. Under excessive pressure, if the material strength is insufficient, extrusion may occur, leading to seal failure.

Environmental Conditions

Ozone, ultraviolet radiation, and outdoor exposure can also shorten O-Ring service life. For example, NBR tends to crack outdoors, while EPDM and FKM provide effective resistance against these external factors.

Cost and Service Life Balance

Although O-Rings themselves are inexpensive, improper material selection can lead to frequent replacement and equipment downtime, significantly increasing overall maintenance costs. The best strategy is to balance cost and longevity based on application requirements, rather than focusing solely on the lowest price or the highest specification.

2. Comparison of Common O-Ring Materials and Their Properties

NBR (Nitrile Rubber)

Offers good resistance to oil and fuels, with low cost, making it one of the most common materials. Widely used in hydraulic and industrial systems. However, it has limited high-temperature resistance and is unsuitable for long-term exposure to ozone or outdoor environments.

HNBR (Hydrogenated Nitrile Rubber)

HNBR is an upgraded version of NBR. Through hydrogenation, its heat resistance, oil resistance, and ozone resistance are significantly improved. Commonly used in automotive engines and the energy industry, it is suitable for applications requiring higher reliability.

EPDM (Ethylene Propylene Rubber)

EPDM performs excellently in weather resistance, ozone resistance, and steam resistance, making it particularly suitable for potable water and steam environments. However, it is not oil-resistant and therefore unsuitable for oil-related equipment.

FKM (Fluorocarbon Rubber, Viton^®)

FKM can withstand high temperatures and resist most oils and chemicals, thus widely applied in aerospace, petrochemical, and engine systems. However, it tends to lose elasticity under low temperatures.

FFKM (Perfluoroelastomer, PERFREZ^® )

Known as the “premium solution” among O-Ring materials, FFKM can resist almost all chemicals, with special grades able to remain stable at temperatures up to 300°C. Due to its extremely high cost, it is typically used in high-value industries such as semiconductors, chemical processing, and pharmaceuticals.

Silicone (VMQ)

Silicone has excellent low-temperature flexibility, applicable down to -60°C, and can be formulated into food-grade or medical-grade compounds. However, it has poor wear resistance, making it unsuitable for dynamic sealing.

Other Special Materials

Aflas^® is suitable for acidic environments, while TPU (Thermoplastic Polyurethane) offers excellent wear resistance and strength, often used in high-pressure hydraulic cylinders.

 ▍Further Reading: Ultra-Low-Temperature FKM for Better Sealing Life

3. Material Selection Guide for Different Working Conditions

High-Temperature Conditions

For environments above 150°C, FKM, FFKM, or Aflas^® are recommended. For example, in petrochemical pipelines and turbine engines, where seals must endure prolonged exposure to high temperatures and oil/gas environments, high-performance materials are essential to maintain sealing integrity.

Low-Temperature Conditions

For conditions below -50°C, such as in refrigeration equipment and aerospace industries, VMQ, FMVQ, low-temperature grade FKM, and HNBR are the best options to ensure materials do not fail due to embrittlement.

High-Pressure Hydraulic Systems

In construction machinery and hydraulic cylinders, NBR and HNBR are commonly selected, as they can withstand thousands of psi of pressure while offering good wear resistance.

Chemical Environments

In chemical plants or semiconductor processes, O-Rings must resist acids, alkalis, or organic solvents. FFKM and FKM are the most common choices, while EPDM is suitable for aqueous media or certain chemical agents in automotive cooling systems.

Food and Medical Applications

Silicone (VMQ) and EPDM that comply with FDA and USP regulations ensure no harmful substances are released in food and medical equipment, meeting stringent regulatory standards.

Outdoor and Weather-Resistant Environments

Solar equipment and construction structures require long-term resistance to ozone and UV exposure. EPDM and FKM, with their excellent weather resistance, are ideal options.

4. O-Ring Material Performance Comparison Table

 ▍Further Reading: GMORS UL approved compound are used in automotive, electronics and refrigerant related fields
 ▍Further Reading: Country-specific certifications of drinking water products by GMORS

5. Frequently Asked Questions

Why can't NBR be used in steam sealing?

Because high-temperature steam causes NBR to harden and crack rapidly, leading to seal failure.

Why does FKM fail in low temperatures?

At low temperatures, the molecular chain movement of FKM becomes restricted, leading to reduced elasticity of the material and loss of its sealing performance, resulting in leakage. It is recommended to use low-temperature resistant compounds under such conditions.

Why can the wrong material cause large-scale shutdowns?

Incompatible materials age prematurely, leading to O-Ring failure and forcing emergency equipment shutdowns. The resulting losses are often far greater than the cost of the O-Ring itself.

Is it necessary to use expensive materials to ensure safety?

Not always. High-cost materials such as FFKM are not universal solutions. The correct approach is to select materials according to application requirements to avoid over specification and unnecessary cost.

How to choose materials in environments with both high temperature and chemical exposure?

It is necessary to analyze the primary influencing factor and select materials that provide both heat and chemical resistance, such as FFKM.

What is the difference between OEM and substitutes?

Products from reputable manufacturers come with complete testing and long-term quality assurance, while low-cost substitutes may lack validation and introduce hidden risks.

GMORS Advantages in O-Ring Material Development

Comprehensive Compound Database

GMORS has a broad Compound Database covering materials such as NBR, HNBR, EPDM, FKM, and FFKM, along with international certifications including UL, NSF, WRAS and USP. This ensures the ability to meet diverse industry requirements.

Independent Laboratory and Compound R&D Capabilities

The GMORS laboratory is ISO 17025 accredited, ensuring high credibility in testing processes and results. The lab can independently conduct material analysis, compound design, and performance testing - covering the complete process from raw material selection to final validation. With this capability, GMORS can quickly respond to the needs of various industries, develop custom compounds for specific operating conditions, and ensure product consistency and reliability.

Value of the GMORS Compound Offering Guide

The GMORS Compound Offering Guide systematically organizes the properties, chemical resistance, and application scenarios of different materials such as NBR, HNBR, EPDM, VMQ, FVMQ, and FKM. This manual helps engineers quickly compare material differences and select the most suitable solutions based on working conditions. It not only shortens design and validation time but also improves efficiency and accuracy in R&D and material selection.

Customized Services and Technical Support

The GMORS engineering team can adjust compounds and perform testing based on customer operating conditions, helping to solve problems and significantly reduce maintenance costs.

Conclusion

Material selection determines the service life and sealing performance of O-Rings. Different operating conditions require comprehensive consideration of temperature, media, pressure, and environmental factors, rather than relying solely on cost or a single property as the deciding standard.

With its extensive compound library, international certifications, and professional technical support, GMORS helps customers maintain reliable sealing performance even under the most demanding conditions. To quickly find the right material, we recommend downloading the GMORS Compound Offering Guide or directly contacting the GMORS technical team for expert material selection advice and customized solutions.

 ▍Further Reading: GMORS Material Certification