Gravitational liquid sedimentation particle testing standards are published by ISO. They include the ISO 13317 series for determination of particle size distribution by gravitational liquid sedimentation methods. These cover topics from general principles, fixed pipette methods, x-ray gravitational technique, and balance methods.
This document specifies the principles of particle size analysis by gravitational sedimentation, the principal types of measurement techniques as well as the general rules for conducting measurements, method validation, determination of the uncertainty budget and representation of results. This document covers neither particle migration by centrifugal, electric or magnetic forces nor sedimentation at high particle concentrations (e.g. zone sedimentation). Moreover, this document does not deal with the determination of properties other than sedimentation velocity and particle size (i.e. neither particle concentration, particle shape, particle density, zeta-potential nor apparent viscosity). NOTE This document can involve hazardous materials, operations and equipment. This document does not purport to address all the safety problems associated with its use. Explosion proof analysers are required when examining volatile liquids with a low flash point.
This part of ISO 13317 describes a method using a pipette to determine particle size distribution, typically in the size range 1 m to 100 m, by gravitational sedimentation in a liquid. The method of determining the particle size distribution described in this part of ISO 13317 is applicable to powders which can be dispersed in liquids or powders which are present in slurry form. The method is applicable to powders made up of particles having the same density and of comparable shape. Particles should not undergo any chemical or physical change in the suspension liquid. It is necessary that the particles have a density higher than that of the liquid.
This part of ISO 13317 describes a method for the determination of the particle size distribution of a powder dispersed in a liquid using gravity sedimentation. The measurement of the concentration of solids settling in a liquid suspension is achieved by monitoring the incremental signal absorption from a beam of X-rays. The method of determining the particle size distribution described in this part of ISO 13317 is applicable to powders which can be dispersed in liquids or powders which are present in slurry form. The typical particle size range for analysis is from about 0,5 m to about 100 m. The method is used for materials containing particles of the same chemical composition which produce adequate X-ray opacity.
ISO 13317-4:2014 specifies the method for the determination of particle size distribution by the mass of particles settling under gravity in liquid. This method is based on a direct mass measurement and gives the mass distribution of equivalent spherical particle diameter. Typically, the gravitational liquid sedimentation method applies to samples in the 1 m to 100 m size range and where the sedimentation condition for particle Reynolds number less than 0,25 is satisfied.