An automated Time Domain Reflectometry (TDR) System for liquid level measurements.

TDR (Time Domain Reflectometry) system was developed some years ago and since then it has been extensively used and tested to measure liquid level of all homogeneous and heterogeneous solutions in process units and tanks.The technique relies on the propagation of a stepwise signal through a coaxial probe, installed in a tank, followed by observation, in the time domain, of the reflected signal due to any impedance change along the signal path (i.e. the interface between air and liquid or/and between unmixable liquids).Level measurements performed by this technique are independent from liquid density and temperature; besides, it is possible to mantain a constant image, and thus a control, of both interrogating and reflected signal from the system to the bottom of the tank.Being the technique attractive- from a Safeguard perspective, because of its selftampering features, R&D efforts, described in this paper, have been devoted for system performance improvements particularly toward the automation of the data acquisition and analysis.