In situ scanning leak test method for HEPA filters：part 7 of the series of research practice of the national standard task group for the Code for cleanroom construction and acceptance test

In situ scanning leak test for installed high efficiency particulate air (HEPA) filters is a necessary step to guarantee the quality of clean rooms. However, because particle concentration of dead-air spaces, such as where near the filter frame and support structure, is always high in the actual HEPA filter, leaks in dead-air spaces are mistakenly considered to exist. Presents two different relevant leak test methods, and gives a new reasonable method based on theoretical analysis and experimental research.