| ASTM D2494-13(2020) - 1.2.2020 | ||||||||||||||||||||||
| Significance and Use | ||||||||||||||||||||||
5.1 This test method is considered satisfactory as a referee method for acceptance testing of commercial shipments of yarn or manufactured staple fibers. 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 the samples for such a comparative test 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, a probability level chosen prior to the testing series. If a bias is found, either its casuse must be found and corrected, or future test results for that material must be adjusted in consideration of the known bias. 5.2 Option I is in common use in other countries, particularly in Europe.4 5.3 Option II is used to calculate the commercial mass of as-produced manufactured filament yarns (except some producer-textured yarns), manufactured staple fibers, and tows. This option is intended to reflect the mass of fiber remaining after fiber lubricants and processing aids are removed. 5.4 Option III is used to calculate the commercial mass of spun yarns, textured yarns, tops, and slivers. When materials are sold on a CMRU basis, the purchaser pays for the fiber lubricant or other removable processing aids. 5.5 Option IV is in common use with impregnated aramids. 5.6 When it can be shown that solvent extraction or another method of testing gives the same results, or results that have a constant ratio to those obtained by the scour procedure, that method may be used for routine testing of known production but should not be substituted for a scour on new or unknown material. For the determination of extractable matter, refer to Test Method D2257. 5.6.1 When the finish is not removable by a water scour, a solvent extraction may be substituted on agreement between the purchaser and the supplier. 5.7 Under certain circumstances, samples taken from yarns and manufactured staple fibers and tows can change moisture content rapidly. For this reason, very careful planning and handling of samples are required to prevent major biases in commercial mass results. | ||||||||||||||||||||||
| 1. Scope | ||||||||||||||||||||||
1.1 This test method provides a measurement of the commercial mass of a shipment of yarn or manufactured staple fiber or tow. This test method applies to (1) yarn of all fiber types except silk, glass, asbestos, and bast; (2) tops and slivers of all fiber types except wool, silk, glass, asbestos, and bast; and (3) manufactured fibers or tow, except glass and other fibers used for special purposes such as flock (Note 1). Note 1: For other test methods for measuring mass of fibrous materials, refer to Practice D2720. 1.1.1 Sampling in this test method is primarily for use in acceptance testing rather than production control. manufactured fiber producers usually sample for the commercial “mass” of product on an on-going basis rather than each shipment to a customer. 1.2 Commercial mass has been traditionally based on one of three options depending on the state of the material: (1) dried, unscoured yarn, staple fiber, tow, and so forth, using commercial moisture regain in the calculations; (2) dried, scoured yarn, staple fiber, tow, and so forth, using commercial moisture regain values in the calculations; and (3) dried, scoured yarn, staple fiber, tow, and so forth, using a defined allowance in the calculations. 1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. 1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee. | ||||||||||||||||||||||
| 2. Referenced Documents | ||||||||||||||||||||||
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