The particle size measurement is a process of characterizing a small amount of sample to represent the whole batch of the product. Therefore, sampling is the first and also the most important step of particle sizing. Sampling means taking sample from a large pile of material for testing. The requirements for sampling are:
(1) Sampling dry powders from the powder stream instead of a pile of powders to make sure the sampling is representative;
(2) If has to sampling from a pile of powders, multipoint sampling (at least 4 points) with different depth must be taken and mixed together.
(3) Samples taken to the laboratory must be mixed evenly and then use a small spoon to take from at least four points, put into the instrument for dispersive testing.
(4) When sampling from a suspension, mix the suspension evenly with an electric mixer, take the sample from the center of the suspension, then add the sample into the instrument for particle sizing.
For special samples with high density, coarser size, and wide particle size distribution, add a very small amount of medium to form a paste, then take sample from the paste after mixed evenly.