| abstract |
An apparatus for locating the level of a liquid in a closed metallic container having curvilinear walls with a thickness of from 1/8 to 3/8 inch is disclosed comprising a manually portable transducer having a piezoelectric material for transmitting and receiving sonic waves, and a sonic pulse generator capable of exciting the piezoelectric material to emit sonic signals into the container from a location adjacent the outside wall of such container at a frequency within about 20% of the natural resinate frequency of the container. The apparatus further includes the electronic circuitry necessary for determining that the reception of the sonic signals transmitted into the container is in balance when the transducer is at a location away from the interface of the fluids within the container, and the electronic circuitry necessary for determining the precise vertical location at which the reception of sonic signals transmitted into the container is no longer balanced as the transducer is manually moved toward the interface of the fluids. |