THERMAL DILATATION OF WATER BETWEEN 0-DEGREES-C AND 44-DEGREES-C

A measurement of the thermal dilatation of pure water has been made by detecting the change of buoyancy acting on a cylindrical hollow artifact made of fused quartz immersed in water between the temperatures of 0-degrees-C and 44-degrees-C. The formula for the thermal dilatation of water, free from air, is obtained in terms of the relative density rho/rho(0) at the pressure of 101 325 Pa with an uncertainty of less than 1 ppm is as follows: rho/rho(0) = 0,999 867 75 + 6,786 687 54 x 10(-5) (t/degrees-C) - 9,090 991 73 x 10(-6)(t/degrees-C)2 + 1,025 981 51 x 10(-7)(t/degrees-C)3 - 1,350 290 42 x 10(-9)(t/degrees-C)4 + 1,326 743 92 x 10(-11)(t/degrees-C)5 - 6,461 418 x 10(-14)(t/degrees-C)6 where the temperature of the maximum density rho(0) is 3,983 4-degrees-C in terms of the ITS-90. The uncertainty of the measurement and the derived formula is evaluated to be 0,2 to 0,5 ppm in standard deviation for the same temperature range.