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D4464-15 – Standard Test Method Technical Guide
📐 Scope and Principle of the Test Method
This test method, D4464-15 (Reapproved 2020), specifies the determination of particle size distribution for catalytic materials, including catalysts, carriers, and raw materials. It employs laser light scattering to measure particles from 1 to 300 µm equivalent spherical diameter, though the technique can accommodate larger or smaller particles. The angular intensity of scattered light is measured to compute a volume distribution based on Fraunhofer Diffraction or Mie Scattering theories.
The method assumes spherical particle geometry, resulting in equivalent spherical diameter data. It is the user’s responsibility to address safety concerns as per applicable regulations.
Safety: This standard does not address all safety concerns. Users must establish appropriate safety, health, and environmental practices before testing.
⚙️ Test Procedure and Data Analysis
A sample is dispersed in water or a compatible organic liquid and circulated through a laser beam. Scattered light is collected by photodetector arrays and converted to electrical signals for analysis. Data are processed using Fraunhofer Diffraction or Mie Scattering, with the latter requiring the real and imaginary indices of refraction. Control of particle concentration minimizes multiple scattering, and background scattering from contaminants is accounted for.
Results are reported as particle size distributions following practices like E1617. Precision is evaluated through interlaboratory studies per E691.
Maintain sample concentration below 1% obscuration to avoid multiple scattering and ensure accurate light scattering analysis.
📊 Referenced Standards and Key Terminology
The standard references ASTM practices for terminology and statistical validity. Key terms are defined in Terminology D3766 and include background, Fraunhofer Diffraction, Mie Scattering, and multiple scattering.
| 🟦 Designation | 📏 Title | 📐 Purpose |
|---|---|---|
| D3766 | Terminology Relating to Catalysts and Catalysis | Standard definitions for catalyst terms |
| E105 | Practice for Probability Sampling of Materials | Sampling methods for materials |
| E177 | Practice for Use of the Terms Precision and Bias in ASTM Test Methods | Precision and bias terminology |
| E456 | Terminology Relating to Quality and Statistics | Statistical terms for quality |
| E691 | Practice for Conducting an Interlaboratory Study to Determine the Precision of a Test Method | Interlaboratory study procedures |
| E1617 | Practice for Reporting Particle Size Characterization Data | Standardized data reporting |
Key terminology specific to this standard:
| 📌 Term | 🔍 Definition |
|---|---|
| Background | Extraneous scattering by contaminants in dispersion fluid |
| Fraunhofer Diffraction | Low-angle scattering theory for particles larger than light wavelength |
| Mie Scattering | Electromagnetic theory for particles with diameters near light wavelength, requiring refractive indices |
| Multiple Scattering | Re-scattering of light by particles at high concentrations |
❓ Frequently Asked Questions
🔍 What particle size range does this test method cover? The investigated range is from 1 to 300 µm equivalent spherical diameter, with the technique capable of measuring above and below this range.
💡 Which optical theories are used for analysis? Fraunhofer Diffraction for larger particles and Mie Scattering for particles close to the laser wavelength, or both, are applied.
⚡ How should the sample be prepared? The sample is dispersed in water or a compatible organic liquid and circulated through the laser beam.
📌 What is multiple scattering and how is it avoided? Multiple scattering is re-scattering of light at high particle concentrations; it is avoided by controlling sample concentration, typically below 1% obscuration.