Laboratory apparatus for calibrating optical suspended solids sensors

An apparatus for testing and calibrating miniature to medium-sized optical suspended solids sensors is described. Stable suspensions of sedimentary particles ranging in size from 10−6 to 4 × 10−3 m can be produced in water with concentrations exceeding 100 g 1−1. Flow velocities in the test volume can be varied continuously from 0.1 to 1.5 m s−1 and samples of suspensions can be withdrawn directly with a peristaltic pump for gravimetric and particle size analyses. The apparatus has been used to evaluate the effects of particle size, flow speed and air bubbles on the performance of optical backscatterance sensors and transmissometers.