Multisonic F3001 ultrasonic flowmeter measures the flow velocity of the gas via the transit times of ultrasonic pulses and calculates the flow rate at measurement conditions therefrom. Here use is made of the fact that ultrasonic pulses move faster in the direction of flow than in the opposite direction.

Each sensor is an emitter and a receiver at the same time. Measurements are taken alternatively in both di- rections, i.e. after a transit time has been measured, the emitter becomes the receiver and vice versa. In this way, the impact of the velocity of sound which depends on the gas type, pressure and temperature is eliminated. In order to take the flow profile into account, measure- ments are taken using a total of 6 acoustic paths in 3 parallel planes. In each plane, there are 2 paths crossing each other. The arrangement of paths according to Gauss-Chebyshev guarantees optimum measurements of the flow velocity even in the case of asymmetries, swirl and crossflows. In addition, these variations of the ideal flow profile can also be measured, i.e. a flow diagnosis can be made.