Online Filtration Efficiency Measurement of Oil Mist Filter Based on Long Optical Path Extinction

To measure the filtration efficiency of oil mist filter, a long optical path extinction method for low concentration particles was developed based on the measurement of oil mist particle size and concentration before and after filtration, for which simulation oil mist generator and folding optical path measuring head were designed. The optical path was calibrated as 2 000 mm, and the oil mist particle size distribution and concentration were retrieved by particle extinction spectrum. In the experiment, the average particle size D₃₂ and volume fraction of filtered oil mist were respectively 0.28 μm and 1.5×10^-8, according to which the filtration efficiency was calculated as 93.15%. Results show that the measuring apparatus based on long optical path extinction is suitable for measurement of size and concentration distribution of fine particles (like oil mist particles), which may be used in performance testing and evaluation of high efficient filters.