O-RINGS ARE CRITICAL COMPONENTS FOUND IN COUNTLESS INDUSTRIES.

These small, donut-shaped seals are designed to prevent liquids or gases from escaping tubing or piping. In most cases, o-rings are made from elastomeric materials—polymers that can stretch and return to their initial shape.

When selecting the best polymer o-ring for your application, consider several key variables, such as durability, chemical resistance, temperature range, and cost requirements.

On this page, you’ll learn more about the six primary elastomer materials APM Hexseal uses to manufacture elastomeric rings:

  • Silicone

    Silicone

    This synthetic polymer is made of oxygen, hydrogen, carbon, and silicon. Similar to silicon dioxide or silica, silicone has added organic groups via C-Si bonds.

    For commercial and industrial applications, silicone provides excellent flexibility and resistance to steam, water, and most chemicals. The material can tolerate extreme temperatures ranging from -100 °F to 500 °F (-73 °C to 260 °C). Silicone is also great for outdoor applications because they resist wear caused by ozone and UV light exposure. Its high strength and low compression set make it ideal for o-ring applications, especially those in the medical and automotive industries.

    Silicone o-ring elastomers are a cost-effective option that can be customized by color, size, and other specifications. Features include:

    Compound Letter & Code:
    S 2701
    Relevant Specifications:
    A-A-59588, Class 2, GR60 or GR70
    Service Temperature:
    -80 °F to +425 °F (-62 °C to +219 °C)
    Tensile PSI:
    500-1800
    Elongation %:
    100-800
    Abrasion Resistance:
    Recommended
    Compression Set:
    Recommended
  • Fluorosilicone

    Fluorosilicone

    Fluorosilicone is a polymer with the properties of fluorocarbon polymers and silicone. When compared to silicone, fluorosilicone offers superior temperature tolerance and chemical resistance. O-rings made from this material can withstand temperatures from -80 °F to 400 °F (-62 °C to 204 °C). Fluorosilicone has excellent resistance to oils, fuels, and many other hydrocarbons.

    Like silicone, fluorosilicone has excellent resistance to ozone and UV radiation. The material’s ability to withstand environmental exposure and hydrocarbons makes it an excellent solution for the aerospace, automotive, and oil and gas industries. Features include:

    Compound Letter & Code:
    L 2615
    Relevant Specifications:
    MIL-DTL-25988C, Type 1, Class 1, GR60 or GR70
    Service Temperature:
    -85 °F to +392 °F (-65 °C to +200 °C)
    Tensile PSI:
    600-1400
    Elongation %:
    100-700
    Abrasion Resistance:
    Fair
    Compression Set:
    Recommended
  • Viton® A

    Viton® A Performance Elastomers

    Viton® A is a fluoroelastomer designed and patented by the DuPont company. In addition to having excellent mechanical properties, Viton® A offers resistance to temperatures from -20 °F to 400 °F (-29 °C to 204 °C). The material can also withstand exposure to chemicals like oils, fuels, bases, and acids.

    This high-temperature o-ring material performs well outdoors, as it can tolerate UV radiation and ozone exposure. Viton® A can be found in nearly every industry that works with high temperatures, specifically chemical processing and automotive applications.

    Compound Letter & Code:
    V 5701
    Relevant Specifications:
    ASTM D2000 75 Durometer
    Service Temperature:
    -13 °F to +482 °F (-25 °C to +250 °C)
    Tensile PSI:
    2000-2200
    Elongation %:
    300-400
    Abrasion Resistance:
    Sufficient
    Compression Set:
    Fair
  • Buna N (Nitrile)

    Buna N (Nitrile)

    Also known as nitrile rubber or acrylonitrile butadiene rubber (NBR), Buna N is a synthetic polymer derived from butadiene and acrylonitrile. The material has good resistance to oils and fuels, in addition to possessing excellent mechanical properties.

    The nitrile rubber o-rings can tolerate temperatures spanning -40 °F to 250 °F (-40 °C to 121 °C). It can also tolerate outdoor environments thanks to its resistance to ozone and UV radiation exposure. Buna N O-rings can be found in most industries where oils and fuels are used, particularly in the industrial machinery and automotive industries.

    Compound Letter & Code:
    N 4601
    Relevant Specifications:
    ASTM D2000 70 Durometer
    Service Temperature:
    -167 °F to +248 °F (-55 °C to +120 °C)
    Tensile PSI:
    1500-3000
    Elongation %:
    400-600
    Abrasion Resistance:
    Recommended
    Compression Set:
    Fair
  • Neoprene

    Neoprene

    Neoprene is a synthetic polymer derived from chloroprene. The polymer provides good mechanical properties and chemical resistance, tolerating exposure to oils, fuels, acids, and bases.

    Neoprene performs well with extreme temperatures ranging from -40 °F to 250 °F (-40 °C to 121 °C). Neoprene is well-suited for outdoor use, as it is resistant to ozone and UV radiation exposure. These properties make it common in the sporting goods and construction industries.

    Compound Letter & Code:
    E 3601
    Relevant Specifications:
    ASTM D2000 70 Durometer
    Service Temperature:
    -61 °F to +257 °F (-52 °C to +125 °C)
    Tensile PSI:
    1500-4000
    Elongation %:
    100-700
    Abrasion Resistance:
    Fair
    Compression Set:
    Sufficient
  • EPDM

    EPDM (Ethylene Propylene)

    The synthetic polymer EPDM—short for ethylene propylene diene monomer—is derived from ethylene, propylene, and diene monomer. In addition to temperature and chemical resistance, EPDM provides good electrical insulation.

    O-rings made from EPDM can tolerate temperatures ranging from -60 °F to 300 °F (-51 °C to 149 °C). The material is also resistant to wear from acids, bases, water, ozone, and UV radiation. The polymer is widely used in applications where chemical resistance and electrical insulation are priorities. EPDM is a popular o-ring material type for the water treatment and automotive industries.

    Compound Letter & Code:
    F 7601
    Relevant Specifications:
    ASTM D2000 70 Durometer
    Service Temperature:
    -76 °F to +302 °F (-60 °C to +150 °C)
    Tensile PSI:
    1400-1600
    Elongation %:
    500-600
    Abrasion Resistance:
    Fair
    Compression Set:
    Recommended

ADDITIONAL CONSIDERATIONS

In addition to chemical resistance, temperature range, and environmental exposure, engineers often consider these variables when selecting the ideal elastomer o-ring for an application:

Durability

Durability

Different polymers will have different life spans, especially depending on the environmental factors they encounter, such as extreme temperature and chemical exposure. For example, silicone and EPDM are both used in the automotive industry, but EPDM’s superior resistance to chemicals makes it particularly well-suited for brake fluid sealing applications.

Cost

Cost

Cost should also be considered when selecting the preferred polymer. Viton® tends to be more expensive than other polymers, but its superior durability and longevity can help you save money in the long run.

Customization

Customization

Certain polymers offer better customization options. This includes the ability to add colorants and other additives. For instance, silicone, fluorosilicone, and Buna N can be manufactured with various color options.

Compatibility

Compatibility

Compatibility should be considered for any design. Some polymers are not suitable for certain temperature ranges and chemical exposures. Oil and gas applications where Buna N o-rings are used might degrade silicone o-rings quickly.

Environmental considerations

Environmental considerations

As businesses adapt to offer greener solutions, environmental standards—like carbon footprint and biodegradability—may be worth considering when selecting the best o-ring.

Special considerations

Special considerations

Regulatory compliance or industrial standards may dictate which polymers can be used in certain applications. For example, medical devices require seals made of biocompatible silicone o-rings to prevent adverse patient reactions.

ELASTOMER O-RINGS, SEALS, AND GASKETS FROM APM HEXSEAL

With so many material options available in o-ring manufacturing, it can be difficult to select the right one for your application.

Since 1947, APM Hexseal has been a trusted provider of sealing solutions, such as o-rings and gaskets. Our team can help you choose the best solution based on your unique requirements. We’ll assist you in evaluating temperature ranges, chemical resistance, service life, durability, cost, and all other applicable variables.

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