Measuring device for determining the flow rate and the presence of fluids for parenteral feeding, pharmaceutics or biotechnology or of blood or blood components as the medium, • comprising a measuring tube, • two ultrasonic transducers for and having coupling to the measuring tube and • a receiving part, wherein • the measuring tube is a tube which is U-shaped, is closed on both ends by a tube plate, and has shell flanges arranged on the end regions as a connection, wherein limbs of the U-shape are the shell flanges and at least one region of the shell of the measuring tube is a plane, • wherein the measuring tube is a sterile or sterilizable disposable product, and • in that the receiving part consists of two interconnected and spaced- apart housing parts (3, 4) such that the measuring tube can be placed between the housing parts (3, 4), • in that the housing parts (3, 4) each have an ultrasonic transducer, • wherein at least one of the ultrasonic transducers can be moved by means of a piston such that, for measuring, the ultrasonic transducers are coupled to the tube plates of the measuring tube and, after measuring, the measuring tube is released, • in that the receiving part has at least one sensor for detecting the temperature of at least one region of the measuring tube and thus of the medium in the measuring tube, and in that the ultrasonic transducers and the sensor are connected to at least one data processing system, • wherein, for measuring, one of the ultrasonic transducers is a transmitter and the other oppositely arranged ultrasonic transducer is a receiver of the ultrasonic waves in each case, and in that the data processing system is connected to the ultrasonic transducers and the sensor such that the volumetric flow rate and/or a media check on the basis of the acoustic velocity of the medium and/or a full-empty check and/or detection of air bubbles for minimizing errors during the metering process and/or for process monitoring is determined from the propagation rate of the ultrasonic waves in the medium and the temperature of the medium in the measuring tube. • comprising a measuring tube, • two ultrasonic transducers for and having coupling to the measuring tube and • a receiving part, wherein • the measuring tube is a tube which is U-shaped, is closed on both ends by a tube plate, and has shell flanges arranged on the end regions as a connection, wherein limbs of the U-shape are the shell flanges and at least one region of the shell of the measuring tube is a plane, • wherein the measuring tube is a sterile or sterilizable disposable product, and • in that the receiving part consists of two interconnected and spaced- apart housing parts (3, 4) such that the measuring tube can be placed between the housing parts (3, 4), • in that the housing parts (3, 4) each have an ultrasonic transducer, • wherein at least one of the ultrasonic transducers can be moved by means of a piston such that, for measuring, the ultrasonic transducers are coupled to the tube plates of the measuring tube and, after measuring, the measuring tube is released, • in that the receiving part has at least one sensor for detecting the temperature of at least one region of the measuring tube and thus of the medium in the measuring tube, and in that the ultrasonic transducers and the sensor are connected to at least one data processing system, • wherein, for measuring, one of the ultrasonic transducers is a transmitter and the other oppositely arranged ultrasonic transducer is a receiver of the ultrasonic waves in each case, and in that the data processing system is connected to the ultrasonic transducers and the sensor such that the volumetric flow rate and/or a media check on the basis of the acoustic velocity of the medium and/or a full-empty check and/or detection of air bubbles for minimizing errors during the metering process and/or for process monitoring is determined from the propagation rate of the ultrasonic waves in the medium and the temperature of the medium in the measuring tube.