With the intelligent SONOFLOW sensors for the measurement of the flow rate in thin pipes and tubes SONOTEC presents a new series of sensors for the device automation. The new development serves for a quick and safe identification of the flow rate of liquids. The SONOFLOW is used in the medical technology, automation industry, device- and machine construction as well as in the pharmaceutical plant construction sector. In order to be able to offer cost-effective flow sensors, we aimed for a modular construction of the measuring cell. It consists of two ultrasonic sensors, the metering box and the evaluation electronics. The SONOFLOW is constructed as a component to be integrated into machines and apparatus. The mechanical installation and electrical integration into the control system can be carried out easily. The integration into the measuring system is carried out via the 4 ... 20 mA current output and the pulse output respectively. The serial interface allows an easy parameterization and calibration. Due to the special sensor construction the system provides great advantages in areas with strict hygienic standards. Further advantages of the method are the quick operating principle without any time delay and the fact that there is no wear at the sensor. Even pulsating flows can be measured.