Research On Most Penetrating Particulate Size Efficiency Testing System Of HEPA Filter

Along with the development of the modern industries, the controlling for airborneparticles in the cleanroom become very strict, so the requirement for the performanceand quality of high efficiency particulate air (HEPA) filter become higher and higher.The academic calculations prove that only one tiny leakage of HEPA filter willseriously affect the filtration efficiency of filter, therefore it is necessary to study a setof testing system to measure the performance of the HEPA filter to solve the domesticlagged conditions of the testing method for HEPA filters referring to the relatedinternational 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. Referringto the European standard (EN1822) for HEPA filter testing and other standards, ex.Japanese and American standards, a HEPA filter performance testing platform withscanning system is designed and built. Through the theoretical analysis, the simulationof computational fluid dynamics (CFD) and the contrast of testing experiments, theresearch successfully realizes the combination of integer efficiency testing andscanning efficiency testing according to the principle of economy and practicality. Thedevelopment of the automatic scanning and controlling system makes it easy to checkthe filter.The thesis mainly analyzes several factors which affect the accuracy of scanningtest, including the isokinetic sampling, the overlap of the probe and so on, and putsforward a method to decide the downstream and upstream concentration. The mostpenetrating particulate size (MPPS) of HEPA filter has been gained, which hasvalidated the relations between the velocity and efficiency, as well as the velocity andthe MPPS. The study finds the main factor to confirm the accurate filter leakage ishow to separate the scanning section with the fringe section, and advises confirmingthe number of the critical leak penetration (CLP) according to the filtrationperformance curve of the domestic filter media.The construction of the testing platform will be helpful to the future research inthis field and the establishment of the related national standard in the future.