This ISO standard provides guidance on instrument qualification and size distribution measurement ofparticles in many two-phase systems (e.g. powders, sprays, aerosols, suspensions, emulsions and gasbubbles in liquids) through the analysis of their light scattering properties. It does not address the specific requirements of particle size measurement of specific materials. ISO 13320 is applicable to particle sizes ranging from approximately 0,1 ìm to 3 mm. With special instrumentation and conditions the applicable size range can be extended above 3 mm. Some advance is also noted for particles smaller than 0,1 ìm.For non-spherical particles a size distributi