Comparative studies of HEPA filter leak test with a photometer and a particle counter

HEPA filter leak test methods can be divided into photometer method and optical particle counter method. Due to different measurement principles, professionals think there exist different leak test results about this two methods. Obtains the test results for local filtration efficiency of HEPA filter with this two methods by test. For the same leak point, the local penetration test results are almost the same, no matter whether a photometer or a optical particle counter is used. Analyses the reasons for deviation.