ISO 20998-2-2022 PDF

Full title and description

ISO 20998-2:2022 — Measurement and characterization of particles by acoustic methods — Part 2: Linear theory. This International Standard specifies requirements and guidelines for ultrasonic attenuation spectroscopy in the linear regime, used to determine particle size distributions of a dispersed particulate phase in liquids at dilute concentrations.

Abstract

This document gives requirements for ultrasonic attenuation spectroscopy methods where the measured ultrasonic attenuation spectrum is a linear function of the particle volume fraction (particle–particle interactions negligible). It covers colloids, dilute dispersions and emulsions, and typical particle sizes from about 10 nm to 3 mm; it also gives typical concentration ranges for reliable size measurement and guidance for monitoring dynamic changes in size distributions.

General information

• Status: Published.
• Publication date: 23 August 2022.
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 19.120 (Particle size analysis).
• Edition / version: Edition 2 (2022).
• Number of pages: 33 pages (ISO publication).

Scope

ISO 20998-2:2022 applies to ultrasonic attenuation spectroscopy measurements for determining size distributions of a particulate phase dispersed in a liquid when the attenuation response is linear with particle volume fraction (dilute regime). It addresses applicable sample types (colloids, dilute dispersions, emulsions), typical particle size and concentration ranges, and uses where particle–particle interactions can be neglected; the document is intended to support reliable, repeatable size-distribution measurements and dynamic monitoring in these conditions.

Key topics and requirements

• Definition and assumptions of the linear ultrasonic-attenuation regime (particle–particle interactions negligible).
• Ultrasonic attenuation spectroscopy methodology and theoretical basis for linear theory.
• Typical measurable particle-size range: approximately 10 nm to 3 mm and recommended frequency considerations.
• Recommended concentration ranges for reliable measurements (typical solid-suspension ranges ≈ 0.1 % to ~5 % by volume; emulsions may be measured at higher concentrations).
• Measurement reporting, interpretation of attenuation spectra, and guidance for monitoring dynamic changes (e.g., aggregation/agglomeration).
• Requirements for instrumentation, calibration, and uncertainty considerations specific to the linear regime (guidance for ensuring linearity and minimizing interaction effects).

Typical use and users

Used by research laboratories, quality-control and analytical teams in chemical, pharmaceutical, materials and colloid science, and by manufacturers of ultrasonic particle-sizing instruments. Typical applications include routine particle-size analysis of dilute suspensions and emulsions, method development, process monitoring where non-invasive, in-line or at-line ultrasonic measurements are required, and validation of instrument performance in the linear attenuation regime.

Related standards

ISO 20998 is a multi-part series on particle characterization by acoustic methods. Relevant parts include: ISO 20998-1:2006 (Concepts and procedures in ultrasonic attenuation spectroscopy) and ISO 20998-3:2017 (Guidelines for non-linear theory, for higher concentration regimes). ISO 20998-2:2022 replaces the earlier ISO 20998-2:2013 edition.

Keywords

ultrasonic attenuation spectroscopy, particle size distribution, acoustic particle characterization, linear theory, dilute dispersions, colloids, emulsions, ISO 20998-2, particle analysis

FAQ

Q: What is this standard?

A: ISO 20998-2:2022 is an international standard that specifies requirements and guidance for ultrasonic attenuation spectroscopy methods in the linear regime to determine particle size distributions in liquid dispersions.

Q: What does it cover?

A: It covers the theoretical basis (linear theory), measurement requirements, typical measurable size and concentration ranges, interpretation of attenuation spectra, and guidance for monitoring dynamic changes for dilute particulate systems.

Q: Who typically uses it?

A: Analytical scientists, instrument manufacturers, QC laboratories, and R&D teams in industries working with colloids, dispersions, slurries and emulsions (e.g., pharmaceuticals, chemicals, materials science).

Q: Is it current or superseded?

A: ISO 20998-2:2022 is the current published edition (published 23 August 2022) and replaces the 2013 edition.

Q: Is it part of a series?

A: Yes — it is Part 2 of the ISO 20998 series on measurement and characterization of particles by acoustic methods; related parts include Part 1 (concepts and procedures) and Part 3 (non-linear theory).

Q: What are the key keywords?

A: Ultrasonic attenuation spectroscopy; linear theory; particle size distribution; colloids; emulsions; dilute dispersions; acoustic particle characterization.