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D6393 – Standard Test Method Technical Guide
The ASTM D6393/D6393M-21 standard provides a comprehensive method for characterizing bulk solids through Carr Indices, essential for evaluating material flowability and handling. This test method is suitable for free flowing and moderately cohesive powders and granular materials up to 2.0 mm [1/16 in.] in size, provided they can pour through a 6.0 to 8.0 mm [1/4 to 5/16 in.] diameter funnel outlet when aerated. The standard includes eight measurements and two calculations to derive the Carr Indices.
📐 Overview and Scope of D6393
This standard, issued in 2021 under the fixed designation D6393/D6393M, is integral to geotechnical and industrial testing. It specifies procedures for measuring Carr Indices, which include Angle of Repose, Angle of Fall, Angle of Difference, Loose Bulk Density, Packed Bulk Density, Compressibility, Cohesion, Uniformity, Angle of Spatula, and Dispersibility. The method is designed for materials that flow through a defined funnel outlet and is critical for powder technology applications.
⚙️ Key Measurement Procedures
The measurement procedures involve specific apparatus for each index, such as funnels for angle measurements and density cups for bulk density. The following table lists all Carr Indices per the standard.
| 🟦 Carr Index | 📏 Type |
|---|---|
| Angle of Repose | Measurement (Section 1.3.1) |
| Angle of Fall | Measurement (Section 1.3.2) |
| Angle of Difference | Calculation (Section 1.3.3) |
| Loose Bulk Density | Measurement (Section 1.3.4) |
| Packed Bulk Density | Measurement (Section 1.3.5) |
| Compressibility | Calculation (Section 1.3.6) |
| Cohesion | Measurement (Section 1.3.7) |
| Uniformity | Measurement (Section 1.3.8) |
| Angle of Spatula | Measurement (Section 1.3.9) |
| Dispersibility | Measurement (Section 1.3.10) |
📊 Data Interpretation and Calculations
All observed and calculated values must conform to the significant digits and rounding guidelines of Practice D6026. The standard emphasizes using SI or inch-pound units independently without mixing. The calculated indices, Angle of Difference and Compressibility, are derived from other measurements, providing deeper insights into material behavior.
💡 Technical Tip: For accurate Carr Indices, ensure the material is aerated to achieve flow through the 6.0 to 8.0 mm funnel outlet, as per Section 1.2.
⚠️ Safety Note: As per Section 1.6, this standard does not address all safety concerns. Users are responsible for establishing appropriate safety and health practices.
❓ Frequently Asked Questions
🔍 What is the maximum particle size for testing?
The standard applies to materials up to 2.0 mm [1/16 in.] in size, as stated in Section 1.2.