A Density and Temperature Invariant Displacer-Type Liquid Level Measuring Method

Level measurement plays a crucial role in a wide range of scientific and industrial applications. Thus, several methods have been proposed for this end, each having its pros and cons. In oil, pharmaceutical and food industries, for instance, liquids may significant temperature and density variations. Therefore, measurement instruments that are sensitive to these variables should be avoided in such cases, which brings the need for the development of techniques that mitigate measurement errors caused by changes in fluids properties. In this paper we propose a level measurement method that is ideally invariant to density and temperature changes. Our method uses the ratio between the buoyancy forces measured by two displacers and two load cells to make it density independent and, as a consequence, temperature invariant. This method was tested through computer simulations and results indicate that it has a high linearity besides being insensitive to fluid temperature and density.