Abstract: An acoustic transducer has an electrically energized crystal in contact with a flexible plate. The crystal drives the plate in a flexural mode. Particularly, the plate is oscillated so that different circular areas of the plate, referred to as nodes, do not vibrate. The nodes separate adjacent annular anti-node areas referred to as positive anti-nodes and negative anti-nodes which oscillate oppositely. An impedance matching material of uniform thickness is disposed between the plate and the surrounding medium to improve efficiency. To avoid cancellation of waves, concentric plastic layer rings are disposed between the impedance matching layer and the oscillating disk. The plastic rings act as a barrier to negative anti-nodes, thus eliminating cancellation between waves from the positive and negative anti-nodes.

Abstract: A leak detecting microphone inserted directly into fluid within a pipe includes a housing having a first end being inserted within the pipe and a second opposed end extending outside the pipe. A diaphragm is mounted within the first housing end and an acoustic transducer is coupled to the diaphragm for converting acoustical signals to electrical signals. A plurality of apertures are provided in the housing first end, the apertures located both above and below the diaphragm, whereby to equalize fluid pressure on either side of the diaphragm. A leak locating system and method are provided for locating fluid leaks within a pipe. A first microphone is installed within fluid in the pipe at a first selected location and sound is detected at the first location. A second microphone is installed within fluid in the pipe at a second selected location and sound is detected at the second location.

Abstract: A pipeline inspection apparatus is disclosed for the detection of corrosion pit type defects, employing one or more ultrasonic transducers to produce a parallel beam for direction toward the pipe wall from inside a pipe, with a sufficiently large beam width to permit comparison of time displayed signal components in defect depth determination, with the signal propagating through a gaseous medium. An additional embodiment combines the same with photographic apparatus.