ISO 9276-1:1998

Overview

ISO 9276-1:1998, "Representation of results of particle size analysis - Part 1: Graphical representation," defines standardized rules, symbols and plots for presenting particle size distribution data. It covers graphical formats for histograms, density distributions and cumulative distributions for solid particles, droplets or gas bubbles across all size ranges. The standard prescribes a consistent nomenclature (e.g., x or d for particle size, q for density, Q for cumulative) and normalization conventions to ensure unambiguous, comparable visual presentation of particle size analysis results.

Key topics and technical requirements

• Standardized symbols and notation: particle size denoted by x (or d), density distributions q(x) and cumulative distributions Q(x), with type index r to indicate number (r=0), length (r=1), area (r=2) or volume/mass (r=3).
• Plot types: normalized histograms, density distributions and cumulative distributions; histogram column areas represent relative amounts ΔQ and total area is normalized to 1 or 100%.
• Relationship between density and cumulative: q(x) = dQ(x)/dx and Q(x) = ∫ q(x) dx, with guidance on obtaining continuous curves from discrete class data (interpolation).
• Equivalent spherical diameter: particle size is reported as a linear dimension - the diameter of a sphere with equivalent measured properties (surface, volume, etc.) - with subscripts to indicate the referenced property (e.g., surface or volume equivalent).
• Logarithmic abscissa: when size spans several decades, plotting on a logarithmic x‑axis is recommended. The cumulative ordinates Q(x) remain unchanged on a log abscissa; density histograms must be transformed so areas under the curve remain constant (standard transformation guidance provided, including the natural/log10 options).
• Example and annex: Annex A supplies a worked example from sieve analysis illustrating calculation of histogram and cumulative plots.

Practical applications

ISO 9276-1 is a foundational reference for producing clear, comparable visualizations of particle size distributions (PSDs). Typical uses include:

• Quality control and reporting in pharmaceuticals, powders, cement, ceramics and minerals
• Particle characterization in environmental, aerosol and soil studies
• R&D and materials characterization in colloids, paints and food powders
• Interpreting sieve analysis, laser diffraction, image analysis and other sizing methods

Who should use it

• Laboratory analysts and QA/QC engineers preparing PSD reports
• Material scientists and process engineers who compare particle-size data
• Regulatory and standards professionals ensuring consistent data presentation
• Software developers generating PSD plots for scientific instrumentation

Related standards

• ISO 9276-2 (Calculation of average particle sizes/diameters and moments)
• ISO 565 (Test sieves - nominal openings) - normative reference used in examples

Keywords: ISO 9276-1:1998, particle size analysis, particle size distribution, histogram, density distribution, cumulative distribution, logarithmic abscissa, equivalent spherical diameter, sieve analysis.