AS 3778.6.7-1992

Measurement of water flow in open channels Measuring devices, instruments and equipment - Ultrasonic (acoustic) velocity meters

Standards Australia

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1 - AS 3778.6.7-1992 MEASUREMENT OF WATER FLOW IN OPEN CHANNELS - MEASURING DEVICES, INSTRUMENTS AND EQUIPMENT-ULTRASONIC...
4 - PREFACE
5 - CONTENTS
6 - 1 Scope and field of application
6 - 2 References
6 - 3 Definitions
6 - 4 Units of measurement
6 - 5 General
6 - 6 Principle of operation
6 - 6.1 Travel time method
7 - 6.2 Sing-around method
7 - 6.3 Difference frequency method
7 - 6.4 Differential travel time method
8 - 6.5 Measurement of time
8 - 7 Characteristics of sound in water
8 - 7.1 Speed of sound in water
8 - 7.2 Transmission of sound in water
8 - 7.2.1 Spreading loss
8 - 7.2.2 Attenuation loss
9 - 7.3 Reverberation
9 - 8 Instrument performance criteria
9 - 8.1 Underwater assembly
9 - 8.1.1 Transducers and cabling
9 - 8.1.2 Mounting assembly
9 - 8.2 Electronic assembly
9 - 8.2.1 Transmitter
9 - 8.2.2 Receiver
10 - 8.2.3 Timer
10 - 8.2.4. Data processor
10 - 9 Site selection
10 - 10 Instrument installation
10 - 11 Operation manual
10 - 12 Calibration
10 - 13 Uncertainties and systematic errors
10 - 13.1 Timing accuracy
11 - 13.2 Velocity of sound variations
11 - 13.3 Crossflow errors
11 - 13.4 Turbulence
11 - 14 Block diagrams
13 - Annex A - Typical minimum clearances with respect to bed and water surface for various path lengths and operating frequencies
14 - Annex B - Systematic errors incurred if the assumed direction of flow is not parallel to the channel axis, for various path l
15 - Annex C - Block diagrams

Abstract

Describes the general design, operation, performance and application of ultrasonic (acoustic) velocity meters for measurement of flow in open channels. It is identical with and has been reproduced from ISO 6418:1985.

Scope

This International Standard describes the general design, operation, performance and application of ultrasonic (acoustic) velocity meters for measurement of flow in open channels.
While it is recognized that, theoretically, such meters might operate at any frequency, practical considerations tend to limit applications to frequencies above the acoustic range, that is, greater than 15 kHz. However, the term "acoustic" has been applied in practice, in many countries, to meters of this type irrespective of frequency and the term is retained in this International Standard for that reason.