The commonly used liquid medium for particle sizing are water, anhydrous ethanol, and other organic solvents. For dry dispersion particle sizing, compressed air or compressed nitrogen are commonly used as gas medium. The main function of the medium is to homogenate the particles, so that the particle size test can be carried out smoothly. Liquid medium should meet the following requirements for particle sizing:
(1) High purity;
(2) No physical or chemical reactions with the particles;
(3) Good affinity with the particles, that is, a good wetting effect on the surface of the particles;
(4) Allow the particles have a proper suspension state;
(5) the temperature difference between the medium and the room temperature should be as small as possible to prevent the sample pool from fogging.
For dry dispersion particle sizing, the gas medium should be pure, dry, adjustable pressure, non-toxic, odorless, and cheap.