Isodaq Technology is now part of Hydro International.

Quantum AquaSound transit-time flow meter


  • High accuracy flow meter for rivers, open-channels or closed conduits
  • Technology - multi-path ultrasonic transit-time method
  • Max velocity paths - 1-8 paths in one channel
  • Width range - 0.5 to 2000metres
  • Depth range - 100mm - 20metres
  • Accuracy - typically 2% - 5% of flow reading depending on site.

Quantum Aquasound irrigation gauge

Full Description

“A quantum leap in open-channel flow meter accuracy and quality”

 The Quantum AquaSound system is a fixed ultrasonic multi-path flowmeter station which calculates flow directly from the measurement of water velocity and depth by applying the time-of-flight or transit-time method.

Transit-time transducers are linked either via a cable or for wide channels via a revolutionary wireless communications system when a long cable run is either impractical or too expensive e.g 100-400meters.  A responder system is also available, whereby both the transmitter and receiver are placed on the same bank some distance apart.  On the opposite bank, the responder unit receives the ultrasonic signal, amplifies it and sends it back.With the transit-time method, velocity transducers are mounted on both banks of a channel and located diagonally to the flow direction.  A pulse of sound travelling diagonally across the flow in a downstream direction will be faster than a pulse travelling in an upstream direction.  The difference in travel times is directly proportional to the mean velocity and therefore discharge is calculated by measuring the depth (and thus the area) of the channel.

This velocity-area method overcomes the inherent limitations of traditional methods of volumetric flow measurement which usually require the construction of a weir  or flume.  Hydraulic structures such as these are very expensive and obstructive, and can ‘drown out’ in high flow conditions causing gross inaccuracy in flow measurement. 

Quantum Aquasound transit-time flow meter

The benefits of the Quantum's transit-time technology is substantial :-

  • High accuracy method for open-channels and closed conduits
  •  Multi-path systems need minimum maintenance
  •  Lowest-cost of ownership of any open-channel method
  •  Only ‘small-works’ civil engineering required at most sites
  •  No obstruction of flow i.e flood risk and fish passage friendly
  •  Responder and wireless system option ideal for wide channels
  •  Battery powered from renewable power sources e.g solar
  •  Real-time telemetry communications easily established

For installation in rivers, open channels, or closed conduits, the Quantum AquaSound operates over the full bi-directional flow range without causing obstruction or head loss.  While this ultrasonic method is traditionally
associated with applications where the water is relatively clean and free from weed  and entrained air, the Quantum AquaSound meets the demands of applications such as sewer-flow measurement at treatment works or in urban culverts.

Typical applications :-

  •   Abstraction measurement
  •   River-flow monitoring
  •   Water resource management
  •   Irrigation flow management
  •   Sewage treatment works
  •   Effluent discharge compliance
  •   Hydroelectric power generation
  •   Leak Detection in Trunk Mains

About the manufacturer :-
Quantum Hydrometrie GmbH was founded in 1994 in Berlin, Germany  and has since supplied more than 600 ultrasonic transit-time systems around the world. In January 2014 Isodaq Technology and Quantum Hydrometrie signed a strategic partnership agreement to develop and promote to the market real-time flow meters based on ultrasonic methods