US Patent 7841243 Speed of sound and pipe size detector

An ultrasonic transit time approach is used for measuring both a speed of sound of a fluid and a diameter of a pipe through which the fluid flows. A reflecting structure is provided to split an acoustic beam generated by a transducer into two portions. One of these portions traverses an acoustic path of known length in order to determine the speed of sound in the fluid. The second portion of the beam may be directed along a path that includes reflections from an inner surface of the pipe. In this case the second portion of the beam can be used to measure the diameter of the pipe. Alternately, the second portion of the beam may extend to a second transducer that is spaced apart along the pipe from the transducer generating the split beam.