Hydrometer Analysis Test Set

Based on the sedimentation principle, this method measures the settling velocity of soil particles suspended in water to evaluate the distribution of very fine fractions. Using calculations derived from Stokes’ Law, particle diameter and mass percentage are correlated, enabling detailed classification of sand, silt, and clay fractions. The system includes a 151H or 152H hydrometer, six 1000-mL glass sedimentation cylinders, a temperature-controlled water bath, circulation pump, high-speed mixer, sodium hexametaphosphate, and a glass beaker. The high-speed mixer and sodium hexametaphosphate ensure dispersion of soil particles into a homogeneous suspension. The temperature-controlled water bath stabilizes liquid viscosity throughout the test, improving repeatability. Hydrometer readings are taken at controlled time intervals, and variations in slurry density at each measurement are correlated with particle size. Test results are used to construct the particle-size distribution curve.