ISO 18747-1-2018 PDF

Full title and description

ISO 18747-1:2018 — Determination of particle density by sedimentation methods — Part 1: Isopycnic interpolation approach. This part specifies an isopycnic interpolation method to determine the density of solid particles or liquid droplets dispersed in a liquid, using the migration (sedimentation/creaming) direction in liquids of different densities to identify the isopycnic (neutral buoyancy) point.

Abstract

ISO 18747-1:2018 defines a procedure based on Archimedean buoyancy and migration behaviour: particles dispersed in continuous liquids with densities lower and higher than the particle density are observed and the change in migration direction is analysed to interpolate the liquid density at which particle migration ceases (isopycnic point), which equals the particle density. The method assumes particles of the same material composition.

General information

• Status: Published (confirmed in systematic review 2023).
• Publication date: 2018-03 (March 2018).
• Publisher: ISO — International Organization for Standardization.
• ICS / categories: 19.120 (Particle size analysis / sieving).
• Edition / version: Edition 1 (2018).
• Number of pages: 28 (ISO publication page).

Scope

This document specifies an isopycnic interpolation approach for determining the density of solid particles or liquid droplets dispersed in a liquid continuous phase. It covers the principle that when a particle’s mass force equals the buoyant force it achieves neutral buoyancy (no net migration), and describes how observing migration direction in liquids of differing densities can be used to interpolate the particle density. The method is intended for systems where particles do not change composition or volume in the test liquids and where all particles in the sample are of the same material composition.

Key topics and requirements

• Principle: Archimedean buoyancy and neutral buoyancy (isopycnic point) as the measurand basis.
• Measurement approach: observe migration direction (sedimentation vs creaming/flotation) in at least two liquids with densities bracketing the particle density and interpolate to the zero-migration density.
• Sample assumptions: particles assumed to be of uniform material composition (no polydispersity in density) and stable (no swelling/shrinkage) in the test liquids.
• Requirements for test liquids: use liquids with known densities (and, where relevant, controlled viscosity and temperature) that span the expected particle density.
• Data and uncertainty: guidance on experimental design, replicate measurements and calculation of uncertainty for the interpolated density result.

Typical use and users

Applied in research and industrial laboratories for particle characterization and quality control. Typical users include materials scientists, formulation scientists (paints, coatings, emulsions), pharmaceutical and colloid researchers, environmental laboratories, and instrument manufacturers and service providers offering sedimentation/centrifugation measurement services. The method is used where in situ, non-destructive particle density information is needed for dispersed systems.

Related standards

ISO 18747-1 is part of the ISO 18747 series on particle density by sedimentation methods; a closely related document is ISO 18747-2:2019 (Part 2 — Multi-velocity approach). Other relevant standards and technical references include ISO 13318-2 (centrifugal liquid sedimentation — photocentrifuge method) and ISO 14887 (sample preparation — dispersing procedures for powders in liquids), which cover complementary measurement techniques and preparative procedures.

Keywords

particle density; isopycnic interpolation; sedimentation; creaming; buoyant density; density determination; centrifugation; particle characterization; ISO 18747; particle measurements.

FAQ

Q: What is this standard?

A: ISO 18747-1:2018 is an International Standard that specifies the isopycnic interpolation approach for determining the density of particles dispersed in a liquid by observing migration direction in liquids of different densities.

Q: What does it cover?

A: It covers the measurement principle (buoyancy and neutral buoyancy), experimental considerations for choosing test liquids and preparing samples, the measurement of migration direction (sedimentation vs creaming), interpolation to the isopycnic density, and guidance on data handling and uncertainty.

Q: Who typically uses it?

A: Laboratories and practitioners who characterise particulate dispersions — including academic researchers, industrial R&D and QC teams in coatings, pharmaceuticals, colloids and materials science, and providers of sedimentation/centrifugation measurement services.

Q: Is it current or superseded?

A: ISO 18747-1:2018 was published in March 2018 and was last reviewed and confirmed (systematic review) in 2023; the ISO record shows the document as current/confirmed.

Q: Is it part of a series?

A: Yes — it is Part 1 of the ISO 18747 series (particle density by sedimentation methods). A related part is ISO 18747-2:2019 (Multi-velocity approach); other measurement standards in the same technical area (ISO/TC 24/SC 4) include methods for centrifugal sedimentation and sample preparation (for example ISO 13318-2, ISO 14887).

Q: What are the key keywords?

A: Particle density, isopycnic interpolation, sedimentation, creaming/flotation, buoyant density, centrifugation, particle characterisation, ISO 18747.