VOLUME MEASUREMENT OF 1 kg WEIGHT BY HYDROSTATIC WEIGHING USING TWO ZERODUR DENSITY STANDARD SPHERES

摘要

The hydrostatic weighing apparatus using two zerodur density standard spheres is built, and the weight exchanger, which is composed of a weight pan with the shape of a conoid and the standard weights with a slot, is constructed. In addition, the temperature and density gradient of transfer liquid are precisely corrected according to the measuring position of the liquid container. As a result, the volume of 1 kg standard weight in a class E1 obtains 124,90388 cm{sup}3 at 20°C with a precision of 8.4·10{sup}(-5)cm{sup}3 (0,67 ppm) by hydrostatic weighing, and the measurement uncertainty shows 3,0·10{sup}(-4) cm{sup}3 (2,4 ppm) in a confidence level of 95% with coverage factor k=2.