Transit-time ultrasonic flowmeters measure the time from when a signal is transmitted from the first transducer until the second transducer receives it. Time measurements are taken in both directions, with and against the flow. If there is no flow in the pipe, the time measurements will be the same in both directions. With flow in the pipe, the sound waves will move faster traveling with the flow and slower traveling against the flow. The liquid velocity is calculated from the difference in these two time measurements. With the area of the pipe and velocity known, the meter can calculate the volumetric flow rate.

SonoPro® ultrasonic flowmeters incorporate high accuracy transit-time ultrasonic technology to deliver accurate and reliable flow metering. The innovative design incorporates matched precision transducers and signal processing circuitry to accurately measure the flow of most liquids over a wide range of velocities.

SonoPro® meters are available with clamp-on or insertion transducers. Clamp-on meters have no wear, create zero pressure loss, and do not require process interruptions to install them since they are attached to the outside of the pipe.
 
With the addition of external temperature inputs, SonoPro® meters can provide a reliable (BTU) energy measurement.