Patent ID: 6490933
Filing Date: 2002-12-10
Classification: G01F

Abstract:
An ultrasonic flow meter comprising a measurement tube for flowing a fluid to be subjected to measurement, said tube being constructed of a metallic material capable of propagating ultrasonic wave and being free from obstacles hindering the flow of the fluid in the tube, a first oscillator fitted to the outer circumference of the measurement tube, a second oscillator fitted to the outer circumference of the measurement tube at a predetermined interval along the flow of the fluid from the first oscillator and a plurality of acoustic filters fitted to the measurement tube between the first and second oscillators for cutting high frequency range of the oscillating wave propagating through the oscillating tube, in which the flow rate of a fluid is measured based on a time difference between a time required when the ultrasonic wave from the upstream oscillator reaches the downstream oscillator and another time required when the ultrasonic wave from the downstream oscillator reaches the upstream oscillator, wherein the acoustic filters are separated by an inner distance and comprise flanges having a thickness and the product of the inner distance of the acoustic filters and the thickness of the flanges is inversely proportional to said high frequency range of the oscillating wave.