A Fully Automatic Calibration System for Hydrometers in NIM

Abstract Hydrometers are widely used in industry for liquid density measurement. It is important to achieve rapid and high accuracy calibration hydrometers. Based on the Archimedes principle, a fully automatic hydrometer system NIM was designed using Cuckow’s method. The of n -tridecane (C 13 H 28 )is calibrated with 441 g high-purity fused silica ring as solid standard. buoyancy measured by static weighing resolution 0.01 mg. alignment between surface scale achieved lifting platform positioning 10 μm. According value air liquid, correction at different scales calculated. Hydrometer covering full range (650–1500) kg/m 3 can be without changing liquid. Taking data PTB reference, experimental show that measurement uncertainty this better than 0.3 division ( k = 2).