Sound - sonar, for the measurement of liquid levels

摘要

1517109 Ultrasonic pulse-echo liquid level measurement ENDRESS & HAUSER GmbH & CO 22 Oct 1976 [24 Oct 1975] 44064/76 Heading G1G In ultrasonic pulse echo measurement of liquid level from above, the lower end of a coupling tube is gradually reduced in solid cross-section, e.g. as in a to e of Fig. 3, 7 denoting through-holes, over an axial length greater than the acoustic wavelength, thereby achieving a progressive impedance match and inhibiting disturbing reflections.