This part of ISO 13317 describes a method using a pipette to determine particle size distribution, typically in the size range 1 µm to 100 µm, by gravitational sedimentation in a liquid. NOTE This part of ISO 13317 may involve hazardous materials operations and equipment. This part of ISO 13317 does not purport to address all the safety problems associated with its use. It is the responsibility of the user of this part of ISO 13317 to establish appropriate safety and health practices and to determine the applicability of the regulatory limitations prior to its use. 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.