Ultrasonic Flow Equipment:

Devices like as ultrasonic flow equipment use the Doppler frequency shift of ultrasonic signals reflected  from  discontinuities  within  the  fluid  stream  to  acquire  flow  measurements. Those discontinuities could be suspended solids, bubbles, or interfaces produced through turbulent eddies within the flow stream. A sensor is mounted on the outer of the pipe and an ultrasonic beam from a piezoelectric crystal is transmitted through the pipe wall into the fluid at an angle to the flow stream. A Signal reflected off flow disturbances are detected through a second piezoelectric crystal situated in the similar sensor. Transmitted and reflected signals are compared in an electrical circuit and the corresponding frequency shift is proportional to the flow velocity.