Description   O-rings are solid-rubber seals that are shaped like a doughnut. When pressed between two mating surfaces, O-rings block the passage of liquids or gases.   Types of Seals   O-rings can form a static or dynamic seals. A static seal is where the O-ring does not move and is used simply for containing pressure or maintaining a vacuum. Dynamic seals can be reciprocating (like a piston and cylinder), or rotating (shaft rotating in a housing). Straight threads used...
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Q & A on O-rings

We asked our users for their input on O-rings. Here are the results of 505 users familiar with O-rings.

Who Took Our Poll? | Design Trends | Applications and Use | Features | Buying Advice

Design TrendsTop

Q:
What new technologies are influencing o-ring design?
67 answers
Answers:
O-rings are, for the most part, a pretty mature product. New technologies have focused more on materials (such as FFKMs) to improve chemical compatibility or increase the temperature window for the material. There has been some limited product focus on reducing friction in dynamic applications (e.g. Greene Tweed LF10 coatings).
~Michael H, Engineer, Houston, TX
In my industry, high pressure air dryers can significantly impact o-ring design. Dryers have many switching and purge valves that require o-rings to seal properly even in the event of high pressure (over 200 psi) and high heat (300+ degrees). They have to survive those conditions, plus typically be exposed to air with oil mist.
~Quality Control/Assurance, Jeffersonville, IN

Molding process to eliminate flash in the center of the cross-section coincident to the the outside and inside diameters. Evolution of compounds less prone to explosive decompression, higher pressure applications, and tolerance to wider range of media.

~Neil design engineer/inventor/entrepreneur, Canada
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Q:
From your perspective, which companies are creating the most innovative o-rings?
64 answers
Answers:
From an FFKM perspective, both DuPont (Kalrez) and Greene Tweed (Chemraz) products continue to push the envelope of where elastomeric gaskets can be applied.
~Michael H, Engineer, Houston, TX
We use Parker, and a few others, but I consider nobody to be extremely innovative as the technology is really quite mundane, and not usually proprietary in any way.
~Chad P, Design Engineer, MN
Seals Eastern, Inc., TRP Polymer Solutions Ltd, Parker, Sigma Freudenberg NOK Pvt. Ltd, Dupont.
~Satyawan B, Research & Development, Mumbai, India
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Applications and UseTop

Q:
What are some of the applications you have used an o-ring for?
126 answers
Answers:

Pneumatic pistons, static seals/glands-high pressure gas applications, hydraulic cylinders, valve seats, pneumatic & hydraulic actuators, pilot valves, reciprocating actuators, bumpers/shock absorbers and motion transmission (like a belt and pulley system).

~Neil design engineer/inventor/entrepreneur, Canada
Code 61/62 connections SAE J1453 & ISO 6149 & SAE J1926 port connections - mobile hydraulic systems. HNBR o-rings for A/C systems on off-HWY machines. DIN 7603 Form A copper seals time to time on European engines - oil & fuel systems.
~Chad P, Design Engineer, MN

Water, Hydraulic Fluids, Gas & Oil, Food and life sciences, Chemical Industry, Agricultural, Pulp and Paper, Mining, Power Generation,Valves,Flanges, Dispensing Equipment, Hydraulic Cylinders, Transportation Industry.

~Justin C, Regional Manager, Montreal, Canada
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Q:
Please share with us any “non-standard” applications that an o-ring has been used for.
44 answers
Answers:

Typically, as o-ring I.D. increases, the cross-sectional diameter increases. We have many applications requiring large I.D. o-rings with smaller C-S diameters than available, forcing us to make our own sizes. We'd rather not do this as some applications are to seal between mating parts operating at up to 10,000 psi. atomizing applications.

~Joel F, Project Manager, Cinnaminson, NJ
Gaskets are sometimes used on equipment not for sealing but for centering components on or within a cylindrical assembly. In some cases, the O-ring friction is also used as a drive (prevent rotation) for a component. O-rings have also been used as a cushioning device to prevent hard contact between surfaces.
~Michael H, Engineer, Houston, TX

In jack assembly of floor crane, O rings were used as jack seals inserted in a Teflon ring machined locally. Ready made O-rings were fitted on the PTFE ring machines with the grooves for outside and inside sealing. Assembly worked successfully for the emergency maintenance job.

~Mukesh G, Engineer, Kota (Rajasthan), India
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Q:
Do you know of any disastrous mistakes that occurred due to the incorrect usage of an o-ring?
41 answers
Answers:
Know your port machining standards!!! I heard of a case where someone put an ISO 6149 fitting into a tapped port. The threads fit OK, but the undercut on the port didn't work with the undercut on the fitting, then the O-ring failed. Not good as the fluid was used for steering... could've been worse... say... BRAKES!!
~Chad P, Design Engineer, MN
Incorrect material selection (such as silicone) when used around high power laser optics. Outgassing will cause destruction of all of the optical surfaces due to contamination by outgassed uncured silicone.
~Bob M, V P of Technology, Orlando, FL
Severe extrusion due to combined high pressure and temperature on too soft a compound resulting in flooded equipment. Compression set due to incorrect compound for high temperature resulting in leakage.
~Richard E, Design Engineer, Loughborough, UK
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FeaturesTop

Q:
What would your design or feature "wish list" be for this product?
58 answers
Answers:

Unification of material grades into a common standard to enable the purchase of similar 'o'-rings from different manufacturers. It's a challenge at the moment to identify, for instance, the grade of 'chemraz' that is an equivalent to the 'kalrez' you have specified.

~Matthew P, Design Engineer, Cambridge, UK
All suppliers should simplify their callouts to known standards - I.E. AS568 REV C, ISO 3601, or SAE J515. Coatings can be a bit of "black magic" but on some applications have merit - I could use some training on O-ring coatings maybe.
~Chad P, Design Engineer, MN
I am looking for an O-ring which can perform for years without failure in saturated steam application at 300 deg C temperature (static application). It should not corrode the SS components.
~Satyawan B, Research & Development, Mumbai, India
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Q:
Is there any advice you want to share with users to help them avoid common errors in selection or usage of an o-ring?
53 answers
Answers:

O-ring should be replaced after any maintenance even if deterioration is less. Thickest size O-ring is preferable for a particular size of shaft / housing. Exposure to ozone, air, sunlight should be avoided to enhance O-ring life. Entry of O-ring should be smooth to avoid cuts. Light lubrication (suitable one) should be applied to O-ring during installation.

~Satyawan B, Research & Development, Mumbai, India

Do not remove tag from the O-Ring bunch or envelop till you are ready to use. Do not apply " Any" lubricant on O rings after fitting in the grooves. If it is required to be applied it should be specific for the O-Ring Material and the process service. O-Ring materials, which are not compatible with mineral oils, shall not be coated with Oil based grease etc.

~Mukesh G, Engineer, Kota (Rajasthan), India

In high pressure applications, even static sealing rings are moving and changing shape when pressurized and de-pressurized. Surface finish and the use of support rings can improve service life. A lubricant can also help reduce the wear of the base mat'l. and o-ring skin.

~Technical Support
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Buying AdviceTop

Q:
Do you have any advice for people relative to buying or using o-rings?
52 answers
Answers:

Do not leave the specification of a seal or o-ring until the end of the design process. Work with your seal supplier to determine the correct seal choice as early as possible during your design process. You can then incorporate design features that allow correct installation and choice of 'standard' products to avoid tooling costs etc.

~J S, Director, UK

Stick to standards whenever possible. Use the standards on your internal drawings or in your business system master descriptions. Bear in mind that some materials [liquids] "age" and their pH changes... So the O ring of choice must be compatible with "on-spec" fluid, and aged fluid as well.

~Chad P, Design Engineer, MN

O-ring should be of a reputed company. Material selection has to be based on your application. Exposure to ozone, air, sunlight should be avoided to enhance life. For dynamic application, squeeze should be less i.e. between 10 to 20%.

~Satyawan B, Research & Development, Mumbai, India
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