Study On Efficiency Scanning Testing System Of Most Penetrating Particulate Size For HEPA Filter & ULPA Filter

With the development of modern air cleaning technique, air filtration industry face opportunity and challenge which never had before. the controlling for airborne particles in the cleanroom become very strict, so the requirement for the performance and quality of high efficiency particulate air (HEPA) filter become higher and higher. The academic calculations prove that only one tiny leakage of HEPA filter will seriously affect the filtration efficiency of filter, therefore it is necessary to study a set of testing system to measure the performance of the HEPA filter to solve the domestic lagged conditions of the testing method for HEPA filters referring to the related international newest testing standards of HEPA filter.According to the review of many HEPA filter testing standards over the world, The testing method of HEPA filter tends to use particle counting efficiency. Referring to the European standard (EN1822) for HEPA filter testing and other standards, ex. Japanese and American standards, a HEPA filter performance testing platform with scanning system is designed and built. Through the theoretical analysis, the simulation of computational fluid dynamics (CFD) and the contrast of testing experiments, the research successfully realizes the scanning efficiency testing according to the principle of economy and practicality. The development of the automatic scanning and controlling system makes it easy to check the filter.The thesis mainly intruduce the idea of design and the selection of the apparatus ,analyzes several factors which affect the accuracy of scanning test, including the isokinetic sampling, the overlap of the probe and so on, and analyzes the methods to decide the upstream concentration. The most penetrating particulate size (MPPS) of HEPA filter has been gained, which has validated the relations between the velocity and efficiency, as well as the velocity and the MPPS. The study finds the main factor to confirm the accurate filter leakage is how to separate the scanning section with the fringe section.The construction of the testing platform will be helpful to the future research in this field and the establishment of the related national standard in the future.