Abstract: There is a lack of knowledge on sampling efficiency of sand collector in China. The sampling efficiency of a new flat opening collector for particles with various sizes was calibrated by wind tunnel experiment in the paper. The results show that the average sampling efficiencies are 54.9%, 59.6%, 69.7%, 52.6%, 24.6%, 21.0%, 17.7%, 13.2% for 0.8-1.0, 0.5-0.8, 0.25-0.5, 0.1-0.5, 0.1-0.25, 0.05-0.1, <0.1, <0.05 mm sediment, respectively. Its sampling efficiency is high for > 0.25mm sediment (>50%) and low for < 0.25 mm sediment (<25%). Sampling efficiency of the collector cannot improve constantly with the particle sizes increasing, but has a peak at about 0.5 mm in diameter. There is not obviously changing regularity of sampling efficiency with wind speed increasing, and there is not essential connection between sampling efficiency and wind erosion intensity at all particle sizes. The large disparity in sampling efficiency for different sizes of particles is determined probably by the difference in transporting modes by wind due to different particle sizes and the aperture sizes of the filtering screen.

Key words: new flat opening collector, sampling efficiency, particles with various sizes