The KOBOLD model DUK flow meters are used for measuring, monitoring, metering, and batching of low viscosity liquids. They are highly repeatable, feature a small pressure loss, and offer measurement independent of density and temperature changes. The devices work on the principle of run time difference. Ultrasonic waves in the media are influenced by the rate of flow. Two sensors mounted opposite one another in the pipeline function simultaneously as transmitter and receiver of the ultrasonic signals. If there is no flow, the run times of both signals are identical. If the media is flowing, then the run time of the signal against the flow is longer than the signal with flow. The run time difference, which is determined by a microprocessor, is proportional to the rate of flow.