O-rings are circular molded elastomers used to create a tight seal between two mechanical components. These simple mechanical gaskets present a cost-effective solution for preventing fluid or gas leakage.
Although all O-rings take the same general form, they can be further broken down into three main categories based on the shape of their cross-section.
- Round O-rings are the traditional O-ring shape with a round cross-section. Standard O-rings seal against loss in any direction under very little compressive force, making them highly versatile.
- Square O-rings have a square cross-section which allows them to form a tighter seal even over surface imperfections.
- Quad O-rings are also known as X-rings because of their X-shaped cross-section. The four-lobed design of a quad O-ring provides twice the sealing surface of a round O-ring while still requiring very little compressive pressure.
Materials Available at Arizona Sealing Devices, Inc.
Aside from shape, the material used is one of the most important considerations when selecting an O-ring. Arizona Sealing Devices works with a broad array of materials, each of which is suited to different industrial applications.
Our list of O-ring materials includes:
- Buna/nitrile: One of the most common O-ring materials, Buna/Nitrile has high tensile strength and is resistant to corrosion or abrasion.
- Aflas: Aflas offers a combination of temperature and chemical resistance that is appealing for many oil, aerospace, and general industrial uses.
- Butyl: Butyl seals have an exceptionally low permeability to gas leakage, making them valuable for vacuum-sealing.
- Ethylene propylene: Ethylene propylene has largely replaced butyl because it offers similar properties, but with enhanced ozone and chemical resistance.
- Fluorocarbon (Viton®):Used in engines, fuel-handling systems, and other high-temperature, high-exposure situations, fluorocarbon is one of the best all-around O-ring materials.
- Fluorosilicone: Fluorosilicone is ideal for aerospace fueling thanks to its excellent fuel resistance and temperature stability. It is also gaining broader popularity for static sealing.
- Hydrogenated nitrile: Hydrogenated nitrile is stronger than standard nitrile while retaining a high level of oil and corrosion-resistance.
- Silicone rubber: Silicone rubber provides excellent temperature resistance and is available in medical grades. It is most useful for static sealing in extreme temperatures.
- Neoprene: Neoprene offers high strength and resistance to various chemicals and temperatures. While a good all-around material, its most widespread use is in refrigerator sealing.
- Polyurethane (cast): Cast polyurethane stands out for its abrasion resistance, making it ideal for high-wear situations.
- Polyurethane (millable): Millable polyurethane features similar characteristics to cast polyurethane, but possesses a slightly lower tensile strength.
- Kalrez: Kalrez is common for oil and gas, chemical processing, and paint applications due to its extreme resistance to volatile chemicals.
- Polytetrafluoroethylene (PTFE): PTFE is another material with broad chemical and temperature resistance, but it requires extra care in the installation process due to its lack of elastic memory at room temperature.
O-ring Specifications and Design
An O-ring’s size is defined by its internal diameter (ID), outside diameter (OD), and cross-sectional width (CS), where 2(CS) + ID = OD. Smaller cross-sections result in more compact, cost-effective gaskets that are resistant to decompression. By contrast, larger cross-sections can reduce the risk of leakage.
Other key design considerations include:
- Gland type and fill: Depending on the application, an O-ring might fit into very different opening configurations (gland type) and fill different portions of the opening (gland fill, noted as a percentage).
- D. stretch and O.D. interference: The inner diameter’s range of stretch and the outer diameter’s proportions must often align with certain guidelines, depending on the application.
- Compression squeeze: Different applications and levels of compressive pressure will result in different levels of deformation, known as compression squeeze.
- Extrusion gap: Radial seal O-rings may unintentionally squeeze into a gap under pressure if the design doesn’t properly account for this risk.
O-ring Offerings from Arizona Sealing Devices, Inc.
Arizona Sealing Devices offers a full range of O-rings to suit both general and specialized industrial applications. We currently serve customers in a diverse range of industries, such as:
- Oil and gas
- Food and beverage
- Water systems
- Chemical processing and energy
- Fluid power
We offer standard O-rings for all general applications, as well as O-rings that conform to specific standards such as:
- Military (Mil-Spec)
- FDA (food-grade)
For a complete list of O-rings we offer, take a look at our product catalog. We fulfill orders of any size. For more information about our extensive product line of O-rings, contact us or request a quote.