Ultrasonic flow meters measure flow indirectly by calculating transit time of a sound wave through, or reflecting from, a flowing fluid. The velocity of the fluid has an impact on the transit time, from which a flow rate can be calculated. Attributes of ultrasonic flow measurement that may determine suitability for a particular application include:
Transducers can be clamped on exterior pipe surface where measurement is needed.
Non intrusive measurement technology prevents contact between media and measuring elements.
No significant pressure drop associated with measuring device installation.
Reduced leak potential.
No moving parts.
Comparatively higher cost than some other technologies.
Fluid characteristics must be well known for proper application.
Pipe cross section must be completely filled by media to acquire accurate flow measurement.