Q-Sewage - Flowmeter System for Waste Water

In order to ensure a reliable process control for the entire sewer system and to achieve an optimal technical and economical control, a continuous measurement of any discharge was the goal.

The utilisation of Quantum´s ultrasonic measurement systems in sewers does not depend on the amount of suspended sediments and the load of solids. An adaptation of the output signal power to the specific boundary conditions ensures discharge control independently from varying density and temperature. In Cologne one level as well as two level single path systems were installed in the sewers.

At least two ultrasonic transducers are installed so that acoustic signals transmitted between them run diagonally to the flow.

The acoustic signal running against the flow has a longer travel time than the acoustic signal running with the flow. The difference in travel times is directly proportional to the flow velocity and, when the cross section is known, directly pro- portional to the discharge.

Single path system
For irrotational flows the single level configuration is recommended. Similar to the simplest river configuration, the measurement path is adjusted diagonally to the flow.

Cross path system
In open channel flows sewers superimposed by secondary flows the crossed path configuration is recommended to measure the discharge exactly. With the known water level the discharge can be recorded continuously even when secondary flows exist in the cross-section.

Multiple level system
If the water level is prone to extreme fluctuations, the accuracy of the measurement can be improved with the installation of multiple levels. In multiple level measurements, the vertical velocity distribution found in the cross-section can be measured directly and the after installation calibration becomes unnecessary.