The DIL 556 Dilution System serves for the defined and reproducible reduction of particle concentrations in aerosols. The main application of the DIL 556 dilution system is the verification of test aerosols for testing clean rooms. DIN EN ISO 14644-3 defines the necessity of appropriate dilution systems when using test aerosols for verification. In the applied principle that corresponds to the standard VDI 3491-15, particles are removed from the sample aerosol according to the specified dilution ratio. The particle size distribution remains unchanged.