O-Rings & Custom Shapes

O-Rings: An O-ring is a doughnut shaped object made from an elastomer, plastic or metal material. They are used primarily for sealing but have other uses such as drive belts, bumpers, spacers, etc.

O-Ring Seal: A means of closing off a passageway preventing an unwanted escape or loss of fluid or gas. The seal consists of an O-ring installed in a gland.

O-Ring Sizes: O-ring sizes are described by I.D. (inside diameter) and 
W (Cross-section). There are 369 standard size O-rings ranging in size 
from .029" ID by .040" W to 25.940" ID by .275" W.

There are 119 standard size ID's available in the 5 popular cross-section diameters (.070, .103, .139, .210 or .275 inches).

O-ring sizes are generally described by "dash number" equivalent to Aerospace Standard (AS) 568A or "2 dash" series designations used within the industry.

Additional Sizes: AS568-901 through -932 O-ring sizes are intended to be used for sealing straight thread tube fittings in a boss. In addition, 
hundreds of O-rings of nonstandard dimensions are available from existing tooling.

Elastomeric Compounds: We supply O-rings and Custom Shapes in dozens of different materials, the following are some of the more popular.

Nitrile (Buna-N) - The most versatile elastomer, nitrile has excellent resistance to most petroleum products and fuels and can be compounded over a temperature range of -65 to +300 F.

Nitrile compounds have excellent resistance to compression set or cold flow, tear and abrasion. They do not possess good resistance to ozone, sunlight or weathering.

Fluorocarbon (Viton or Fluorel) - Many designers are switching from 
Nitrile to Fluorocarbons due to the superior combination of compression set resistance, high temperature properties and broad chemical 
resistance. These compounds can be used from -20 to +400 F with brief 
intermittent exposure to +600 F.

Silicone - Silicones possess excellent resistance to temperature 
extremes. Special silicone compounds are capable of either -175 F 
flexibility or heat resistance to +600 F.

Generally used in static seals due to their poor tear and abrasion resistance, silicone compounds are often used for sealing medical products, electrical apparatus or for continuous service in dry air up to 400 F. 20

Fluorosilicone - Combines the good high and low temperature properties 
of silicone, but with much better resistance to a variety of fluids. Fluorosilicones are commonly used in aircraft fuel systems. Temperature range -80 to +350 F.

Ethylene Propylene (EPR, EPDM) - Excellent general purpose temperature 
range (-65 to +300 F) elastomer with superior resistance to water, 
steam, alcohols, engine coolants, sunlight and weathering. It has 
excellent resistance to Skydrol and other types of hydraulic fluids. 
Not recommended for use with petroleum oils or fuels.

Neoprene (Chloroprene) - Has the unique combination of resistance to 
weathering as well as resistance to petroleum lubricants over a 
temperature range from -65 to +300 F. Neoprene also has good resistance to flexing and tear. Commonly used for refrigerant seals.

While the compounds listed here will meet most sealing needs, many other compounds are available. We welcome your questions regarding special needs and applications.

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O-Rings and custom molded parts for your industry