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D2947 – Standard Test Method Technical Guide
ASTM D2947/D2947M, reapproved in 2019, specifies a standard test method for the screen analysis of asbestos fibers. This method uses a mechanical sieve shaker to perform a dry screen analysis, providing insights into fiber length distribution. It is primarily applicable to Group 4 and shorter chrysotile asbestos fibers, as defined in Test Method D3639, and may be suitable for some short amphibole fibers.
📐 Scope and Referenced Documents
This test method covers a dry screen analysis for asbestos fiber by means of a mechanical sieve shaker. It is limited in its application to Group 4 and shorter chrysotile asbestos fiber samples as defined in Test Method D3639. Some short amphibole asbestos fibers may be suitable for evaluation. The values stated in either SI units or inch-pound units are to be regarded separately as standard.
The standard references several ASTM documents for additional context, including sampling methods and sieve specifications.
| 🟦 Standard | 📐 Title |
|---|---|
| D2590 | Test Method for Sampling Chrysotile Asbestos |
| D2946 | Terminology for Asbestos and Asbestos–Cement Products |
| D3639 | Test Method for Classification of Asbestos by Quebec Standard Test |
| D3879 | Test Method for Sampling Amphibole Asbestos (Withdrawn 2009) |
| E11 | Specification for Woven Wire Test Sieve Cloth and Test Sieves |
| E177 | Practice for Use of the Terms Precision and Bias in ASTM Test Methods |
⚙️ Test Procedure and Apparatus
The procedure consists of screening a test specimen through a specified nest of sieves by means of a mechanical sieve shaker. This shaker reproduces the circular and tapping motion of hand-sieving but with uniform, mechanical action, ensuring more accurate and dependable tests. The sieves are ideally suited for measuring particle size when particles are equidimensional, but asbestos fibers differ considerably, so results depart from a true measure of fiber length.
📊 Key Measured Properties and Factors
Test results give an indication of the apparent fiber length distribution in the sample tested. However, 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. These factors must be considered when interpreting results.
⚠️ Health Hazard: Breathing of asbestos dust is hazardous. Always minimize dust exposure and follow safety guidelines as outlined in the standard, including reference to “Safe Use of Chrysotile Asbestos: A Manual on Preventive and Control Measures.”
💡 Technical Note: Sieve analysis is not a direct measure of fiber length due to the non-spherical shape of asbestos fibers. Results should be considered as an apparent distribution influenced by fiber characteristics.
❓ Frequently Asked Questions
🔍 What is the scope of ASTM D2947? It covers dry screen analysis for asbestos fibers using a mechanical sieve shaker, limited to Group 4 and shorter chrysotile asbestos fibers and some short amphibole fibers.
💡 Why is a mechanical sieve shaker used? It provides uniform, mechanical action that reproduces hand-sieving motions, ensuring more accurate and dependable tests compared to manual methods.
⚡ What factors influence screen analysis results? Moisture content, degree of fiberization, harshness, and the tendency for fibers to cling together or to longer fibers all affect screening efficiency and results.
📌 What safety precautions are necessary? Users must minimize asbestos dust exposure, follow health guidelines, and comply with regulatory limitations. Refer to the standard’s warning and manual for safe use.