A New Rotating Coarse Particle Sampler

Abstract

A new portable sampler for collecting coarse particles larger than about 30 μm is described. This rotating coarse particle sampling probe consists of an L-shaped sample probe that is rotated at a known angular velocity such that the probe tip speed is greatly in excess of characteristic ambient wind speeds. The air suction speed through the probe is matched to the probe tip speed, thereby effecting isokinetic sampling conditions. In the prototype design, sample rates of up to 1.3 m³/min (47 ft³/min) are possible, and particles are collected by inertial deposition in the elbow near the probe entrance. Comparisons with independent measurement techniques show that particles up to 250 μm were sampled with 100% efficiency by the new sampler. Particles smaller than about 35 μm were not efficiently collected by inertial deposition in the elbow. This sampler can be applied to studies of coarse particle behavior in the atmosphere. Also, this sampling concept could be extended to other difficult coarse particle sampling problems.