【国外标准】 Standard Test Method for Screen Analysis of Asbestos Fibers (Withdrawn 2022)

4.1 Test results give some indication of the apparent fiber length distribution in the sample tested.4.2 Sieves are ideally suited to measure particle size and particle size distribution when all three axes of the particle are equidimensional or the particle is of spherical shape. Asbestos fibers differ considerably from these ideal conditions and, therefore, results depart from a true measure of fiber length and length distribution.4.3 Characteristics that influence screening efficiency influence test results. Among these are moisture content, degree of fiberization, harshness, and the tendency for fibers to cling together, and of short fibers and fines to cling to longer fibers.4.4 In spite of its shortcomings, this test method is particularly useful because of its simplicity and speed and satisfactory reproducibility.4.5 The test is suitable for specification acceptance and manufacturing control.1.1 This test method covers a dry screen analysis for asbestos fiber by means of a mechanical sieve shaker.1.2 This test method is limited in its application to Group 4 and shorter chrysotile asbestos fiber samples2 as defined in Test Method D3639. However, some short amphibole asbestos fibers may be suitable for evaluation by this method.1.3 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.1.4 Warning—Breathing of asbestos dust is hazardous. Asbestos and asbestos products present demonstrated health risks for users and for those with whom they come into contact. In addition to other precautions, when working with asbestos-cement products, minimize the dust that results. For information on the safe use of chrysoltile asbestos, refer to “Safe Use of Chrysotile Asbestos: A Manual on Preventive and Control Measures.”31.5 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. For specific safety hazard, see 1.4.1.6 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.