Development of a static test apparatus for evaluating the performance of three PM 2.5 separators commonly used in China.

PM separator directly affects the accuracy of PM sampling. The specification testing and evaluation for PM separator is particularly important, especially under China's wide variation of terrain and climate. In this study, first a static test apparatus based on polydisperse aerosol was established and calibrated to evaluate the performance of the PM separators. A uniform mixing chamber was developed to make particles mix completely. The aerosol concentration relative standard deviations of three test points at the same horizontal chamber position were less than 0.57%, and the particle size distribution obeyed logarithmic normal distribution with an R of 0.996. The flow rate deviation between the measurement and the set point flow rate agreed to within ±1.0% in the range of -40 to 50°C. Secondly, the separation, flow and loading characteristics of three cyclone separators (VSCC-A, SCC-A and SCC112) were evaluated using this system. The results showed that the 50% cutoff sizes (D) of the three cyclones were 2.48, 2.47 and 2.44 μm when worked at the manufacturer's recommended flow rates, respectively. The geometric standard deviation (GSD) of the capture efficiency of VSCC-A was 1.23, showed a slightly sharper than SCC-A (GSD =1.27), while the SCC112 did not meet the relevant indicator (GSD = 1.2 ± 0.1) with a GSD = 1.44. The flow rate and loading test had a great effect on D, while the GSD remained almost the same as before. In addition, the maintenance frequency under different air pollution conditions of the cyclones was summarized according to the loading test.