How ultrasonic flowmeter works?
Ultrasonic flow measurement is based on the fact that acoustic energy flows through the medium both upward and downward. The difference in the transit time of the signals is proportional to the total flow rate, or fluid velocity. This method measures the difference in elapsed time between sending the signal from the first sensor to the second sensor.
Measuring fluid flow
If there is no flow in the pipeline, these transit times in each direction are equal. If the fluid is moving in the direction of flow, the sound moves faster. Similarly, the sound moves slower when the medium flows in the opposite direction.