Hybrid flowmeter for large sewer channels

Permanent flow monitoring (overflow & billing) of complex sewage collecting systems


  • The SBGE manages the sewage network, the rain water basins and the wastewater treatment plants of the greater area of Brussels. Brussels-Capital Region is subdivided in 19 municipalities with a total population of 1.200.000 inhabitants

Task definition

  • Complex combined sewer collecting systems, used as storm water reservoirs during rain events. During these events, the flow rate increases dramatically and the collectors get filled with combined sewage & raw water
  • Collector diameters from DN 1800 to DN 2500 mm
  • Custody transfer flowmeters requiring extreme reliability and very good proven accuracy over a wide range of flow rates (data used for billing)
  • Channels have low discharge levels with high velocity during dry weather conditions


  • Installation of a hybrid area/velocity flowmeter associating non-contact ultrasonic and hydrostatic pressure sensor for level with non-contact radar and ultrasonic transit-time for velocity (combined RAVEN-EYE® & FLO-SONIC system)
  • Collected data is transmitted in real time using modern GPRS data loggers allowing remote flow data analysis and data download trough a central system