Overview
ISO 13317-3:2001 - "Determination of particle size distribution by gravitational liquid sedimentation methods - Part 3: X‑ray gravitational technique" specifies a laboratory method for measuring particle size distribution of powders dispersed in a liquid using an X‑ray gravitational sedimentation approach. The method is applicable to powders or slurries with particles of similar chemical composition and sufficient X‑ray opacity. Typical measurable particle sizes are about 0.5 µm to 100 µm. The standard complements Parts 1 and 2 in the ISO 13317 series and includes procedural and reporting requirements.
Key topics and technical requirements
- Measurement principle: continuous monitoring of X‑ray beam attenuation as solids settle; attenuation is proportional to mass concentration and is converted to a Stokes equivalent diameter using the Stokes equation.
- Apparatus: temperature‑controlled analysis compartment, sedimentation cell, collimated X‑ray source/detector, mixing chamber, circulation plumbing; ancillary equipment such as ultrasonic bath or mechanical stirrers is referenced.
- Sample preparation and sampling: follow ISO 8213 for sampling and ISO 14887 for dispersion procedures; recommended sample volume ≈ 50 ml and minimal concentration producing 10–30% beam attenuation.
- Procedure controls:
- baseline (0% solids) and 100% concentration determinations,
- temperature equilibration and minimization of thermal convection,
- bubble elimination in the measurement cell,
- option to reposition cell or X‑ray source to speed analysis.
- Data handling: cumulative mass percent vs. equivalent spherical diameter; represent results per ISO 9276-1.
- Validation and quality: duplicate tests recommended (typical agreement within ~2% for certified materials); validate using certified reference materials where available.
- Reporting: report suspending liquid viscosity and density, effective particle density, temperature, sample preparation details and any dispersants used.
- Safety note: users must observe X‑ray safety and lab health procedures.
Practical applications and users
ISO 13317-3 is used where precise gravimetric particle sizing is needed and where X‑ray opacity of the material permits non‑optical detection. Typical users include:
- Materials testing and analytical laboratories
- Quality control in pigments, ceramics, mineral processing and coatings industries
- Pharmaceutical and chemical R&D teams working with suspensions and slurries
- Producers and users of powders requiring certification or method validation
Benefits include robust mass‑based particle size distributions for suspensions that may be difficult to analyze optically.
Related standards
Keywords: ISO 13317-3:2001, particle size distribution, X‑ray gravitational technique, gravitational liquid sedimentation, sedimentation cell, Stokes diameter, powder characterization.