GB1314521A - Means of flow measurement and detection - Google Patents

Abstract

1314521 Ultrasonic inspection; ultrasonic couplings T E EVANS 22 May 1970 [24 Feb 1969 3 July 1969 30 July 1969 10 Sept 1969] 4179/69 33658/69 38221/69 and 44584/69 Headings H4D and H4J In a method and apparatus for investigating a fluid flowing through a pipe continuous ultrasonic waves originating from a transducer T, Fig. 1, are converted into electrical signals by transducer R and the Doppler-shift and the amplitude of those signals are measured to determine, e.g., flow speed of discontinuities in the liquid, and discontinuity concentration. In the embodiment transducer T is fed from a signal generator 1 of selectable output frequency via an amplitude modulator 2, the modulation frequency also being adjustable. A detector D feeds into a gain-controlled audio amplifier 7 the output from which (i) is fed to a circuit 18 which responds to average signal level and which actuates a meter indicator, a recorder 25 and alarm 24, and controls liquid flow rate, and (ii) is fed to a selectable low-pass filter 8, Schmitt trigger 11, differentiator 15, "negativecut" circuit 16, and frequency-to-D.C. voltage converter 17 to give a flow rate metering, 13, recording, 14, and alarm. Flow rate measurement is assisted by artificially aerating the fluid or introducing gas, another liquid or solid particles. An agitating ultrasonic transducer TT may be added. Compensation for changes in fluid temperature is by controlling the frequency of generator 1 in response to average modulation depth as determined by a circuit 27; other means of compensation are outlined. Ultrasonic couplings. Fig. 2. Piezo-electric transducer C is in a stainless steel holder S for screening and is coupled to the pipe by a liquid G from a reservoir U; a flexible cuff mounting F enables ready attachment to the pipe.