What is an O-ring, and what purposes do various O-rings serve? While an O-ring’s basic function is relatively simple, there are several important considerations to make when choosing the right one for your application to ensure your O-ring can withstand high pressures, temperatures, and other operating conditions. Read on to learn more about O-rings, what various industries use them, and how to select the right O-ring for your needs.

What Are O-Rings?

O-rings, also known as rubber rings or toric joints, are ring-shaped seals possessing a circular cross-section to resemble their namesake letter O. They’re primarily made of a rubber elastomeric material and provide an affordable and reliable means of sealing hydraulic, pneumatic, and related machinery components. It should also be understood that in addition to elastomeric materials such as the standards as Nitrile, Neoprene, EPDM, Silicone, and others, that O-rings are also made from metals, thermoplastics, fluoroelastomers (FKMs) like Viton™, all application-specific materials for optimal performance. Popular for their easy manufacturability and fit, they secure to mating surfaces and prevent pressurized liquids or gases from escaping hoses, piping, and other such system passageways.

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What Are O-Rings Used For

What Are O-Rings Used For?

O-rings have applications across diverse industries to fulfill varied sealing needs.


O-rings are essential to the transportation sector, supporting modes of transport ranging from cars and trucks to railroads, marine boats, and aircraft. The best elastomer for a given transportation application depends on its intended exposure to vibration, temperature extremes, chemicals, and harsh environmental conditions. These O-rings will also have to comply with emission and biofuel regulations, which is why manufacturers continue to innovate to create custom O-rings that meet Tier 1 and OEM standards.

Oil, Gas, & Industrial

Oil and gas refineries use countless valves, fittings, pumps, storage tanks, and other components that require durable seals. O-rings for industrial use must stand up to high pressures and temperatures, as well as corrosive chemicals. Such applications benefit from O-rings composed of peroxide and triazine-cured perfluoroelastomers and other such specialized compounds.


O-ring uses in the electronics industry include protecting sensitive electronic components from contaminants like dust. To fulfill this sector’s need for particulate-free O-rings for applications like semiconductor processing, manufacturers can produce them in clean environments from an array of material options.


The medical sector depends on O-rings for connectors, filtration systems, pumps, and syringes. To ensure product safety for patients and healthcare workers, manufacturers of O-rings for medical equipment must construct them from specialized, medical-grade materials and in sterile clean room conditions.

Food & Beverage

Equipment for food and beverage processing and dispensing, as well as water filtration applications, all require effective, FDA-compliant sealing solutions. Specialized O-rings constructed in accordance with food safety and sanitation standards are available to meet NSF-61 and 3A sanitary requirements.

Considerations for Choosing an O-Ring

While there are numerous types of O-rings available, the right option is the one that precisely matches the intended application. When comparing different O-ring materials, you can make the proper selection by evaluating multiple factors.


Choosing the right material is critical to ensuring an O-ring can handle your application’s:

  • Pressure limits
  • Ambient and operating temperatures
  • Exposure to chemicals, acids and bases, and other sources of corrosion
  • Likelihood of experiencing vibration
  • Industry standards (e.g., sanitation, food safety, etc.)

Pressure Rating

O-rings provide leak protection within pressurized systems, and each comes with its own pressure rating. It’s important to have a thorough understanding of the maximum pressure utilized in your system and select an O-ring with a PSI rating that exceeds that maximum by a safe margin.


In designing for O-ring use, whether standard AS 568A sizes will be used or a custom size, it is critical that not only compatibility to the media being sealed is considered along with temperature and pressure, but also stretch and squeeze of the O-ring for the application, whether it is to be used as a static seal or to be used as a dynamic seal, in which case friction must also be considered.

Durometer Hardness

O-rings must also be the right hardness for their intended application so as not to experience deformation. Manufacturers can verify an elastomer material’s hardness using a Shore durometer. Typical O-rings usually have durometer ratings that normally fall between 40 and 90, meaning that their material is on the softer or harder side, respectively.

O-Ring Solutions From MPRC

Choosing the right seal for your application depends entirely on the use conditions involved. At Master Packing and Rubber Company (MPRC), we specialize in rubber elastomer and related seal technologies to withstand varied environmental exposures and operating conditions. Our cut gaskets and seals support peak performance in your systems, designed for optimal leak protection. O-rings from MPRC are available in a range of material and design options so that we can provide the product versatility that clients in diverse industries require to find ideal sealing solutions. While we produce a variety of customer specific designs, we also provide standard AS 568A sizes and stock in several elastomeric materials.

Contact us to learn more about the various O-rings we offer, or request a quote today.

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