Electronic measurement of fluid level using acoustic sensors

Many fluid tanks are, in effect, a sealed box which, if forced by an acoustic source will resonate at a fundamental frequency dependent upon the volume of the box as well as its shape and the thickness and stiffness of its walls. The introduction of fluid to the bottom of the tank will change the effective volume of the tank as seen by the acoustic source. This will change the acoustic properties of the tank by an amount which corresponds to the amount of fluid in the tank. Three methods of fluid volume measurement based on this principle are presented. Results of these three methods are compared. The advantages of these methods and applications are discussed