Modelling, validation, and metrological characterization of tilt densimeters

Abstract

In the context of craft breweries, a recently invented liquid density meter works by leveraging an unusual principle: the displacement of the center of buoyancy. This meter obtains its measurements from its own tilt while it is floating, but its original implementation converts the measured values from the accelerometer into density measurements with a simple polynomial regression. However, it does not make temperature corrections, so that the influence of this quantity is disregarded in the regression. Additionally, the meter does not indicate its measurement uncertainty. The aim of this study was to create a mathematical model of the phenomenon, which was not found in the existing bibliography; use the model to obtain an estimate of the measurement uncertainty; compare the uncertainty methodologies of the GUM and the one that uses the Monte Carlo method of its Supplement 1 and use the second approach to validate the first; perform experiments with a meter, comparing the results with a laboratory densimeter; and perform the metrological characterization of the meter. The maximum expanded uncertainty over the measuring interval between 1.0000 g/cm3 and 1.1000 g/cm3 was 0.0028 g/cm3 (k = 1.96, 95 %).