SOME OBSERVATIONS ON AIR MOVEMENTS IN CLEAN ROOMS WITH UNIDIRECTIONAL AIR FLOW

To avoid particle contamination in clean process production, unidirectional air flow with HEPA-filtered air is used, either in the entire room or partly in the critical process region (clean air zones), the purpose of this presentation is to describe a number of observations in unidirectional air flow and to discuss the interaction between air movements and the dispersion of airborne contaminants, it has been shown, by using smoke photography technique, that wake regions and vortex streets can easily be formed behind the working operator and objects. If a contaminant is emitted in the region of a vortex an accumulation can occur. It is important for the user to investigate that such vortices do not occur in the clean working zone.