Volumetric
Volumetric Measurement is the measurement of Liquid Volumes. Volumetric measurement includes measurement made through positive displacement, turbine, sonic nozzle, vortex shedding, mass flow and other types of meters. We will not cover the measurement of product in gaseous (vapour) state.
It also includes measurement by static volumetric measures. Calibration of volumetric metering systems is usually done through comparisons to a standard volumetric prover vessel or by series flow through a pipe or piston prover. In the case of a Mass Flow Meter (Coriolos Meter), proving may be accomplished by mass to mass comparison using a scale of known performance.
Much of the calibration of volumetric measures is done using water as the medium. This is done for various reasons including safety, ease of obtaining the product and the well know characteristics of water. Calibrations done using water are often referred to as a "water draw". To use water as a transfer medium, you often need to know the density of water. While most of us assume water has a density of 1 kg / 1 litre, this is not exactly true. Water density changes with temperature and with purity. The following graph shows the density as compared to temperature of air free water using the formula established by Wagenbreth & Blanke.
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A PDF copy of the Wagenbreth & Blanke densities from 0.01° Celsius to 40° Celsius in 0.01° increments, is available from APLJaK Ventures.