ISO 9276-1:2025

Overview

ISO 9276-1:2025 - Representation of results of particle size analysis: Part 1, Graphical representation provides unified guidelines for plotting particle size distributions (PSDs). It defines standard nomenclature and instructions for producing histograms, distribution densities, and cumulative distributions from measured particle size data. The document applies to PSDs of solid particles, droplets and gas bubbles across all size ranges and supports comparability between methods and instruments.

Key topics and technical requirements

• Standardized terms and symbols: clear definitions for particle, particle size (x), equivalent diameter and type-of-quantity subscripts (r).
• Types of quantity (subscript r): r = 0 (number), r = 1 (length), r = 2 (area), r = 3 (volume/mass); plus non‑geometrical subscripts such as “ext” (light extinction) and “int” (light intensity).
• Graphical formats:
  • Cumulative distribution Q(x) - normalized undersize distribution (0–1 or 0–100%); oversize is 1 − Q(x).
  • Distribution density q(x) - obtained from the cumulative distribution by differentiation: q(x) = dQ(x)/dx, and Q(x) = ∫ q(x) dx.
  • Discrete histograms - representation of data in size classes with rules for obtaining class values and plotting.
• Logarithmic abscissa: guidance for plotting cumulative and density functions on a log scale to emphasize multi‑decade size ranges.
• Non-normalized and two‑dimensional distributions: instructions for concentration distributions, separated particle distributions, and combined shape/size plots.
• Examples and annexes: illustrative examples (sieving, aerosol number concentrations, two‑dimensional PSDs) to aid implementation.

Practical applications and users

ISO 9276-1:2025 is relevant for any organization that measures, reports or interprets particle size data:

• Laboratories and quality control in pharmaceuticals, chemicals, ceramics, mining, food and cosmetics.
• Aerosol and environmental monitoring teams reporting particle number or mass distributions.
• Instrument manufacturers and software developers producing PSD analysis and plotting tools.
• Researchers and regulators needing consistent, comparable PSD visualizations for specification, reporting and regulatory compliance.

Benefits include improved communication between suppliers and clients, greater comparability of PSDs from different measurement methods, and clearer interpretation of particle population characteristics.

Related standards

• ISO 9276-1:2025 is part of the ISO 9276 series on representation of PSD results. Consult other parts of the series for complementary numerical, statistical or methodological requirements.