ASTM D2591Standard Test Method for Linear Density of Elastomeric Yarns (Short Length Specimens)
Significance and Use
This test method is considered satisfactory for acceptance testing of commercial shipments because current estimates of between-laboratory precision are acceptable and the method is used extensively in the trade for acceptance testing.
5.1.1 If there are differences of practical significance between reported test results for two laboratories (or more), comparative tests should be performed to determine if there is a statistical bias between them, using competent statistical assistance. As a minimum, use samples for such comparative tests that are as homogeneous as possible, drawn from the same lot of material as the samples that resulted in disparate results during initial testing, and randomly assigned in equal numbers to each laboratory. The test results from the laboratories involved should be compared using a statistical test for unpaired data, at a probability level chosen prior to the testing series. If bias is found, either its cause must be found and corrected, or future test results for that material must be adjusted in consideration of the known bias.
Linear density of elastomeric yarns is used in some calculations for tensile and elastic properties.
The test method is based on elastomeric yarns in lthe “as-produced” condition, but may be used for treated elastomeric yarns provided the treatment is specified. The method does not cover the removal of finish for the determination of linear density of “finish-free” elastomeric yarns.
Before conducting ASTM D2591, it is important to read the entire specification. Standards can be obtained from appropriate standard authorities.