Depth gauge

A piezoelectric liquid gauge system for a tank, the system comprising a piezoelectric device adapted to transmit a sound wave in a liquid and to receive said wave in order to determine the distance traveled by the wave in the liquid on the basis of the time between transmission and reception, said piezoelectric device comprising two distinct active piezoelectric portions adapted to generate a sound wave towards a reference obstacle and a sound wave towards a surface of the liquid to be gauged, respectively, wherein the active piezoelectric portions are contained in a housing adapted to be fixed in a position in the tank in which a measurement is to be performed, the reference obstacle extending over a face of the housing which faces one of the active portions, said face also having a measurement opening that faces the other active portion and is adapted to allow the sound waves to pass through, wherein the inside of the housing is subdivided into two volumes:

• a reference first volume;
• and a measurement second volume;
• the two volumes being separated by means of a separator tube extending from the top wall of the housing substantially in register with the separation between the two active portions, and terminating before making contact with the active portions fixed to a bottom of the housing.

A piezoelectric liquid gauge system for a tank, the system comprising a piezoelectric device adapted to transmit a sound wave in a liquid and to receive said wave in order to determine the distance traveled by the wave in the liquid on the basis of the time between transmission and reception, said piezoelectric device comprising two distinct active piezoelectric portions adapted to generate and to direct a sound wave towards a reference obstacle and a sound wave towards a surface of the liquid to be gauged, respectively, wherein the active piezoelectric portions are contained in a housing adapted to be fixed in a position in the tank in which a measurement is to be performed, the reference obstacle extending over a face of the housing which faces one of the active portions, said face also having a measurement opening that faces the other active portion and is adapted to allow the sound waves to pass through, wherein measurement quality is improved by separating the sound waves coming from the reference obstacle from the sound waves coming from the surface of the liquid to be gauged by a separator tube.