PSL Aerosol Generators for ULPA and HEPA Filter Testing

A PSL Generator is designed to challenge ULPA and HEPA cleanroom filters as part of the efficiency certification process. HEPA filters provide 4/9 and 5/9 efficiency ratings, while ULPA filters provide 6/9 and 7/9 ratings. PSL spheres at 0.3 um are generally used to challenge HEPA filters and detect pin hole leaks, while PSL spheres at 0.15 μm or 0.12 μm are used to challenge ULPA filters and detect pin hole leaks. The rate of PSL challenge is extremely important, considering a 6/9 filter has the capability to trap 99.9999% of all particles flowing through the filter. That is 1 particle in 1 million that can get through a 6/9 filter, thus in order to challenge a filter with this high efficiency, a high volume PSL generator is required. PSL Generators can achieve this high volume output of 7.2×10 10 at 0.10 μm. The PSL aerosol is mixed with the appropriate airflow and the DI water evaporates from the spheres prior to filter contact.