Discussion on principles of determining medium velocity limits of HEPA filters

Wang Junmin, Peng Yongsen, Liu Chao and Liu Zhengjie

2021.03.22

By comparing the average medium velocity limits of HEPA filters in the literatures of the different technology systems at present and the same technology system at past and present, finds that the requirements of ASME AG-1-2019 and GB/T 17939-2015 are too conservative and some literatures relax the corresponding requirements or replace them with other requirements. Considering that the medium pleated configuration of filter pack and the average medium velocity have significant influences on the uniformity of airflow distribution and the initial resistance of the HEPA filters, suggests that the average medium velocity limit should be determined according to the principles of the maximum local medium velocity of the HEPA filter not exceeding the allowable medium velocity under the acceptable penetration rate of the filter medium and the maximum flow capacity of the filter not exceeding the allowable flow capacity under the expected initial resistance, on the basis of the medium pleated configuration of filter pack with optimal comprehensive resistance.