The Aerosol Dilution System DIL 550 is designed to accurately dilute aerosols to produce a defined particle concentration for certain measuring tasks. The main application of the dilution system DIL550 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.
From the aerosol stream to be diluted a sample is taken through a thin capillary. Particle concentration of the capillary flow rate remains unchanged whereas a HEPA filter removes nearly all particles from the bypassing flow rate. After the capillary and filter both streams are mixed together again and the dilution ratio results from the ratio between the two single flow rates.
Optical Particle Counter like LAP 340, have a physical limit up to which concentration they work accurately. Is this concentration exceeded errors will inevitably occur. According to standard VDI 2083 for testing clean rooms and work benches it is compulsory to carry out measurements with increased concentrations in the incoming aerosol. By using the dilutor DIL 550 upstream of a particle counter a dilution factor of up to 100 can be achieved. Thereby particle concentrations of >106 Particles per cf (1cf = 28,3l) can be reduced to 104per cf. This will put the particle concentration well within the range of standard particle counters.