Patent ID: 8347734

Claim:
A method for determining and/or monitoring flow of a measured medium through a measuring tube with a first ultrasonic sensor and at least a second ultrasonic sensor, wherein the first ultrasonic sensor has at least one electromechanical ultrasonic transducer element, and the second ultrasonic sensor has at least two electromechanical ultrasonic transducer elements, the method comprising the steps of: placing the first ultrasonic sensor in a first region of the measuring tube; placing the second ultrasonic sensor in a second region of the measuring tube in such a manner that ultrasonic signals transmitted through the measured medium from the first ultrasonic sensor are received by the second ultrasonic sensor, and that the ultrasonic signals transmitted through the measured medium from the second ultrasonic sensor are received by the first ultrasonic sensor; ascertaining volume flow and/or mass flow of the measured medium flowing in the measuring tube using at least one control/evaluation unit, which, ascertainment is based on ultrasonic measuring signals, or based on measurement data, which are derived from the ultrasonic measuring signals by means of a travel-time difference method; during a diagnostic phase, ultrasonic signals are transmitted from the first ultrasonic sensor through the measured medium to the second ultrasonic sensor; at least one process variable is ascertained and/or derived from received ultrasonic signals for each electromechanical ultrasonic transducer element of the second ultrasonic sensor; and the electromechanical ultrasonic transducer elements of the second ultrasonic sensor, which are to be active in a following measuring phase, are selected based on the process variable of the received ultrasonic signals.