Analysis of the Density and Temperature Invariant Displacer-Type Liquid Level Measuring Method

A new displacer-type liquid level measuring method has been proposed by Souza, Carvalho and Canuto [1], this method was tested through computer simulation and results indicate that it has a high linearity besides being ideally insensitive to fluid temperature and density. However, these simulations disregarded some characteristics of the method implementation. In this paper we analyze the influence of buoyancy on the rod that connects the displacer to the load cell (see Fig. 2), and of the presence of a second phase in the liquid tank. Finally, we present and test a sensor prototype. Simulation results show that the rod buoyancy introduces a non-linearity in the system and the second phase adds a small measurement error. Real experiments indicate that the sensor prototype can be used in order to test the effectiveness of the method proposed in [1].