HEPA Air Filters in Pharmaceutical Cleanroom Industries: A Review and Selecting Proper Analytical Model Against Several Particle Capture Mechanisms

High-efficiency particulate air (HEPA) filters, as a vital part of the pharmaceutical industry, are responsible for separating particulates from the air. These filters separate particulates of different diameters from air and send them to pharmaceutical production areas known as clean rooms. Among the various mechanisms that exist for particle capture in filter media, HEPA filters trap particulates mostly through three main mechanisms: diffusion, interception, and inertial impaction. However, the complexity of these mechanisms is such that despite various research and articles, we have not yet achieved a specific and unified equation that is consistent with the experimental results in reality. Therefore, in this article, we have tried to describe the key factors affecting the mechanisms of particle capture in HEPA filters, put together and compare all the relationships and equations proposed by different researchers on this subject. So we can choose the best relationship and model from them according to our required geometry and working conditions.