Keywords: 
•   /
• rotational speed /
• river arenous sediment /
• laser particle analyzer

Abstract: The experimental results show that :(1) the sediment particles are vulnerable to be broken because of the brunt. When the propeller of the laser grainsize equipment rotates quickly, larger particles would be broken to smalls with grain size of 32~87 μm, at the same time, the ultrasonic disaggregating of the laser grainsize equipment would also shatter the sediment particles; therefore, the ultrasonic disaggregating of the laser grainsize equipment should not be available. (2) The sample shading degree would be influenced by the rotatespeed of the laser grainsize equipment. During the test, we found that the slower rotational speed of the equipment, the less instability of the measure result. But with the slowing rotatespeed, the differences of the  shading degree and blue light shading degree of the samples become bigger. The sample shading degree is mostly stable when the rotational speed of the laser grainsize equipment is 500 r/min, but the water power is so inadequate that the larger particles can't be pumped into sample injector, hence the sample shading degree is lower, and the differences of the  shading degree and blue light shading degree of the samples become bigger.(3) It would contribute to more serious damage of large particles if the rotational speed is too fast, on the contrary, the low speed would lead the sediment particles not to disperse equably in the solution. Analyses that accounted for the stability of measure results, the sample shading degree, the grain size changes and content changes during the test shows that the appropriate rotational speed is about 1 900~2 000 r/min. So the comprehensive analysis can be concluded is that the appropriate rotational speed of Mastersizer 2000 laser particle analyzer is about 1 900~2 000 r/min for the river arenaceous sediment, and the ultrasonic disaggregating of the laser grainsize equipment should not be available. 