ITS-90 Density of Water Formulation for Volumetric Standards Calibration.

Area of Science:

• Metrology
• Physical Chemistry
• Fluid Dynamics

Background:

• Accurate density and compressibility data for water are crucial for precise scientific measurements.
• Existing formulations may not meet the accuracy requirements for modern metrology.
• The 1990 International Temperature Scale (ITS-90) provides the standard for temperature measurements.

Purpose of the Study:

• To present a new formulation for the density of air-saturated water as a function of temperature on ITS-90.
• To develop a new equation for calculating the isothermal compressibility of air-saturated water on ITS-90.
• To provide accurate data for the gravimetric determination of the volume of volumetric standards.

Main Methods:

• Developed a new empirical formulation for water density based on experimental data.
• Derived a new equation for isothermal compressibility from the density formulation.
• Validated the equations within the temperature range of 5 to 40 °C on ITS-90.

Main Results:

• A new, accurate formulation for the density of air-saturated water was established.
• A novel equation for isothermal compressibility was successfully developed.
• The proposed equations provide reliable values for water properties in the specified temperature range.

Conclusions:

• The new formulations offer improved accuracy for water density and isothermal compressibility calculations.
• These equations are suitable for use in the gravimetric determination of volumetric standards.
• The findings contribute to enhanced precision in metrological applications.