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ASTM Specifications

ASTM Specifications


Most quality manufacturers of Orings specify the physical properties of their product through ASTM (American Society of Testing and Materials) and/or SAE (Society of Automotive Engineers) designations. The purpose of doing so is to provide a standardized method of calling-out the required physical properties of a rubber product, based primarily on its Type (Heat Resistance) and Class (Oil Resistance). An example of an ASTM Specification for a general purpose, sulfur-cured, 70 Duro Nitrile may be:

ASTM D2000-99 M2BG714 B14 EA14 EF11 EF21 EO34 Z1


 

ASTM Line Call-outs

An ASTM D2000 line call-out, which is considered a specification, shall contain the following information:



Revision Year
In this case, the document date is 1999.

M
If the M is present, the unit of measure is expressed in Metric units. If the letter M is not present however, the unit of measure is in English units (as in psi for the tensile strength). Prior to 1980, all ASTM specifications were in English units. Beginning in 1980, the Metric unit call-outs became the standard.

Grade Number
The Grade Number designates instances where more extensive tests are required. Any grade other than 1 mandates additional requirements that are spelled out in Table 6 of the D2000 document.

Type
Indicates the Heat Resistance properties of the elastomer.

Class
Indicates the Oil Resistance properties of the elastomer.

Hardness
The Shore A Durometer hardness requirement of the elastomer. In this case the 7 calls out 70 +/- 5 Durometer.

Tensile Strength
This indicates the minimum tensile strength of the elastomer. If the designation has an M after the Revision Year, then this call-out is stated in Metric units, megapascals (MPa). If no M is present, then the call-out is specifying the English unit, pounds-per-square inch (psi). In this example, the 14 is calling-out 14 MPa. The conversion to psi is: MPa x 145 = psi. Therefore, the psi Tensile Strength requirement of this designation is 14 x 145 = 2030psi.

Suffix Requirements
These indicate the additional testing requirements needed to satisfy this specification call-out. Each requirement is comprised of a suffix letter, calling out the property being tested, and the suffix numbers, which call out the the test method and test temperature. Z suffix tests denote a customer added or specific test that is not necessarily covered by the D2000 document.