The standard near-silicon liquid (2329kg/m3) is a mixture liquid of tribromopropane and dibromoethane in a certain proportion. This liquid is used to measure the density of single crystal silicon spheres by a static suspension method and the analysis of the difference in the micro density between two silicon spheres. Measuring the difference in the micro-density of the silicon spheres is of great significance for the new definition of the new mass of kilograms. In order to obtain the micro-density difference of the silicon spheres, it is necessary to calculate the static pressure value and the temperature by separately adjusting the singlecrystal silicon spheres to the same suspension state and the compression coefficient of the near-monocrystalline silicon density liquid. Through the adjustment of the same hydrostatic suspension state of a single silica ball in different suspension states, the linear constants measured by the linear model are analyzed to calculate the liquid compression coefficient. For this purpose, a static suspension measuring device for a single crystal silicon ball was designed to maintain the water bath within a range of ±0.1mk within 3 hours, and the position control of the silicon ball was determined by controlling the pressure of the upper computer.
Due to perfect stability, deionized water is usually used as one important reference material for density and volume calibration. To evaluate suitability of pure water density formulas for deionized water, one measurement system based on Archimedes’s principle was designed, and silicon ring was used for density standard to measure the density of deionized at 20°C. The experimental result shows that The Tanaka equation can be used to calculate the density of deionized water with deviation 5ppm. The uncertainty budget of measurement is analyzed, and the combined relative uncertainty is 4.09ppm (k=2).