JPS57517A - Ultrasonic flowmeter - Google Patents

Abstract

PURPOSE:To eliminate abnormal signals owing to foreign matters or the like and to measure flow rate with high accuracy by allowing the passage of a measurement signal only when the output pulse number from a threshold comparator for the output signal of a forward ratio receiver and a set number coincide. CONSTITUTION:The burst waves from a burst wave oscillating circuit 1 are applied via an amplifier 2 to radio transmitters 3-1, 3-2, and are received in radio receivers 3-3, 3-4. The received signals are inputted via amplifier circuits 4a, 4b, threshold comparators 5a, 5b, time-amplitude conversion circuits 6a, 6b to a gate circuit 11 connected to an arithmetic circuit 7 which operates the forward-backward propagation time of the burst waves. The gate circuit 11 counts 8 the signal number above a certain threshold level of the threshold comparator 5a and compares the same with the set number of a count setting circuit 10. Only when they coincide, the gate of the gate circuit 11 is opened by a count comparator 9 and at the time of the abnormal signal, no flow rates are measured.