Verification

The use of reference material is recommended to verify the correct function of the particle sizing equipment. A simple electrical, mechanical or optical test is generally not sufficient, as all functions of the measuring process, such as dosing, transportation, dispersion etc. are only tested with sample material applied to the instrument.

Reference Materials

Many vendors supply certified standard reference materials which either address a single or a group of instruments. As these materials are expensive, it is often more advisable to perform only the primary tests with these materials and perform secondary tests with a stable and well split material supplied by the user. For best relevance, the size range and distribution type of this material should be similar to the desired application. It is essential that the total operational procedure is adequately described in full detail [S. Röthele, W. Witt, Standards in Laser Diffraction, 5^th European Symposium Particle Char.,Nuremberg, 24-26 March 1992].