O-rings are robust sealing solutions for nearly endless applications in every industry. They will only work well, though, if you choose the right o-ring from the start. If you use the wrong material, profile, or size, your o-ring’s integrity will inevitably suffer and, ultimately, fail.
With competitive price and timely delivery, NFJ sincerely hope to be your supplier and partner.
The good news is that you have the resources to make the right choice for your team right here. There are essentially five steps to choose the correct o-ring for your application. Barring unique application challenges, you should have the information to make the right decision for your seal after reading through these resources.
If you have any questions or unique considerations, our team is happy to help you find a solution quickly.
To determine if that step is necessary, let’s walk through the five steps to choosing the right o-ring for your application.
Before you can do anything else, you need to identify exactly what challenges your o-ring will face. We consider the following:
You should also be aware of any regulatory requirements of your application, such as USDA 3A, USP CL VI, or FDA CFR 21.
Once you have the list of challenges your application will face and relevant regulations, you can get into the meat of choosing your o-ring.
One of the most important parts of choosing an o-ring is identifying the right material. A few popular options include FFKM, PTFE, EPDM, and NBR.
FFKM overcomes:
FFKM is best suited for high- or low-operating temperature applications and applications with aggressive solvents, chemicals, or media that would cause other materials to fail. It is used in almost every industry, particularly oil and gas, medical and pharmaceutical applications, and semiconductors.
PTFE overcomes:
PTFE is best suited for applications that do not need a high compression set but also excellent chemical and temperature resistance. These include medical devices, coatings, and pest control. It also works well in ultra-low temperatures, like aerospace and automotive manufacturing.
EPDM overcomes:
EPDM is best suited for weatherproofing because it can withstand extreme elements. It is frequently found in roofing, windows, doors, cell towers, and other outdoor applications. It also works well with applications that use steam, automotive brake fluid, vibration dampeners, and isolators.
NBR overcomes:
NBR is universally used in basic sealing applications because it is low-cost and offers comprehensive benefits and physical properties. We see it often in automotive, water treatment and filtration, and pool and spa applications.
NBR can be formulated to excel in harsh environments, including aerospace and other low-temperature applications.
Use our comprehensive chemical compatibility guide to ensure the material that best meets your needs will also be compatible with the chemicals you use. The guide also includes a cost gauge to help you choose an option in your budget early on.
There are a few common profiles for an o-ring, but there are numerous solutions for a variety of challenges your seal might face. This knowledge is important, but we always have experts ready to help you choose the right material, profile, and size for your seal to ensure success.
With that being said, let’s lay out some profile basics!
First and foremost, there is the tried and true o-ring. O-rings are incredibly versatile and offer a wide range of solutions for almost any application and industry. These sealing solutions can also be paired with complementary fittings that help them function better in your application.
While o-rings are often a solution, they might not be the best solution for your application.
X-rings (or quad-rings®) are similar to o-rings, but their cross-section forms an X with four contact points. These are an alternative to o-rings and are recommended for low-speed reciprocating or oscillatory motions that are twisting, rolling, or bunching.
U-cup lip seals are in the same general shape as an o-ring, but the cross-section is a U. U-cups can function independently, but they also have the unique option of being “loaded.” A loaded u-cup has an o-ring or spring energizer nestled into its internal groove.
U-cups are designed for dynamic reciprocating applications up to PSI, but loaded u-cups can handle up to 5,000 PSI.
Glyd Rings® combine the power of a Turcon-based slipper seal with an energizing o-ring to extend the life of an o-ring in dynamic, reciprocating applications. They use an interference fit that couples with the extra tightness of the o-ring to ensure a quality seal at lower pressure.
The company is the world’s best Custom friction and sealing material solutions supplier. We are your one-stop shop for all needs. Our staff are highly-specialized and will help you find the product you need.
Sizing is by far the trickiest but most important part of choosing an o-ring. When we diagnose failed seals, an improperly sized o-ring is often the culprit.
To start, review gland design basics. Then, you will need to determine the way pressure works in your gland. Your operation will be one of the following:
Now, to determine your sizing, you will want to know the following gland measurements:
For Internal pressure:
For Internal Vacuum:
For Dynamic Rod and Piston:
For Static Rod and Piston:
Now that you have your important measurements, you can use a comprehensive sizing chart to select the correct sized o-ring. The following links will take you to the corresponding sizing chart for your appropriate region:
USA O-Ring Sizing Chart
Common Metric O-Ring Sizing Chart
Japanese JIS O-Rings Sizing Chart
British BS O-Ring Sizing Chart
Last but certainly not least, you will need to choose your supplier. Your supplier should be your collaborative partner in consolidating and streamlining your sealing needs. To help you identify the exact questions you should be asking suppliers, we’ve included a comprehensive list in our Complete Guide To Choosing An O-Ring.
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Custom seals offer some fantastic advantages but for many general applications standard rubber seals, gaskets and mouldings are fine. There may also be times when the up-front cost of a standard rubber part make it seem like the sensible option.
However if you’re unsure which route to take here are nine reasons for choosing custom seals as a better alternative.
A standard product just won’t do. For example, when the moulding is a major part of the end product, such as the rubber boot for the sub-sea cable connector pictured above.
Custom seals can be designed with multiple point contact offering greater seal protection.
Design custom rubber parts with less ‘squeeze’ to maintain a more effective seal and resulting in reduced friction. This can also be combined with fluorination techniques to reduce flash.
Customised materials and design can result in seals lasting longer.
This resulting longer seal life can lead to lower maintenance and operational costs.
Tooling is designed to ensure finish and the ability to hold tolerances as required, including flash removal techniques.
Criteria like temperature, pressure, liquids, contaminants, exposure to processes, light, out-gassing and just plain old water may necessitate a custom solution.
Occasionally, the introduction of new regulations will extend the role of the seal. For example, a seal originally designed to prevent ingress of dirt and fluids into a ruggedised electronics unit can be enhanced to shield against EMI.
Sometimes the requirement for a seal, gasket or moulding is only recognised late in the process or perhaps you know you need a seal or moulding but aren’t exactly sure how it could work.
Whatever your situation reach out and get in touch. We can help.
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