Ultrasonic flow meters offer a number of advantages over other flow measuring technologies. The most distinct of these advantages is the non-invasive nature of ultrasonic measuring technique: fluid flow can be measured by clamping a pair of transducers onto the outside of the pipe without contacting the measured fluid.
This installation method, unique among flow metering technologies, allows ultrasonic flow meters to be used in applications where the process cannot be shut down and/or the pipe cannot be cut for installation. Clamp on flow meters also cause no pressure drop, suffer no mechanical wear and tear, allow for bidirectional measurement, and provide the ability to pass unlimited solids past the meter without damage.
Fluid velocity is measured by sending an ultrasonic pulse from an upstream transducer to a downstream transducer and back again. The measured difference in the amount of time that each pulse takes to traverse the pipe is directly proportional to the mean fluid velocity. ultrasonic flow meters use this measured velocity to calculate the liquid flow rate based on user-entered information about the process application.