O-Rings

O-Rings

Additional Information
There are several different standards to choose from when it comes to O-ring dimensions.  The most popular in the United States is the AS568 standard for O-ring sizes and tolerances.  Maintained by the Society of Automotive Engineers, this standard allows the user to choose from five different cross-sections with inside diameters ranging from 1/32" to 26". Tube fitting boss seals are included in AS568 as 900 series O-ring sizes, and are intended for use in MS33649 (now superseded by SAE-AS5202) straight thread tube fitings. 

RT/Dygert also offers a wide array of metric sizes, in both standard and non-standard dimensions.  As a subset of the metric sizes offered, we also stock many Japanese Industrial Standard (JIS B2401) sizes. If an O-ring with special size or fluid resistance is required, RT/Dygert can provide custom O-rings, specially made to your demanding requirements.
SIZES
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Fit Groove Size
O.D.
AS568A
Dash No.
C/S
I.D.
Metric
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AS568A012
Dash No.
US Nominal
I.D. .364" ± .005" 3/8
O.D. .000" 1/2
C/S .070" ± .003" 1/16
Volume .005in3

MATERIALS
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Polyurethane

Non-Stock Material

Other Designations

AR; EU; Adiprene® Vibrathane® (Uniroyal)

Composition

Polyurethane diisocyanate

Temperature Range

-40 to 180 °F

Description

Polyurethane rubber is notable for its combination of hardness with elasticity, outstanding abrasion resistance and tear strength. Elastomeric urethane rubber, not to be confused with thermoplastic polyurethane, may be either ether (EU) or ester (AU) base, with the latter being the far more common of the two. It is often referred to as the "millable gum" urethane. The ester based polymer is superior in resistance to abrasion and heat, while the ether based polymer has better flexibility at low temperatures. Polyurethane is a moderately expensive material whose use is usually limited to applications that require its outstanding physical properties. Common end use applications are industrial seals, industrial rolls, O-Rings, caster wheels, gaskets, shoe soles and conveyor belts. Peroxide is the most commonly employed cure system, but sulfur curing is also possible in the extremely complex vulcanization chemistry involved in polyurethanes.
Information above applies to the generic material. Specific compounds may exhibit different properties.

Physical Properties*

  Excellent Good Fair Poor
Abrasion resistance •      
Compression Set     •  
Elongation   •    
Flame resistance       •
Gas permeability   •    
Low temperature flexibility •      
Tear resistance •      
Tensile strength •      

Chemical Resistance*

  Excellent Good Fair Poor
Air   •    
Alcohols   •    
Aldehydes       •
Concentrated acids       •
Concentrated Bases       •
Ethers     •  
Ketones       •
LP Gas     •  
Mineral oil   •    
Oxidation •      
Ozone •      
Silicone Fluids •      
Steam       •
Sunlight   •    
Weather •      
*Excellent, good, fair and poor are intended to serve as general guidelines only. Actual testing in the application environment is always recommended.
Information above applies to the generic material. Specific compounds may exhibit different properties.