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SQ Flow Meters


The radar sensors of the SQ series continuously measure the discharge (flow) volume of sewer systems, ducts, semi-filled pipes and other technical channels in the fields of wastewater and industrial effluents. Due to the contact-free measurement deposits and other solids in the water do not harm the sensor. This is especially advantageous for the measurement of wastewater. The compact design allows an installation in manholes or in sewage systems.


  • Non-contact measuring, maintenance-free system
  • Discharge calculation through continuous measurement of flow velocity and water level (increased accuracy as through level measurement only)
  • No structural work necessary in the water
  • Simple installation and integration in existing measurement and process control systems
  • Data output via multiple interfaces: RS 485, Modbus, SDI-12, pulse signal, analog
  • Uninterrupted accuracy - measures also with high turbidity and solid contents in the wastewater and at very little discharge rates
  • SQ-U and SQ-8R: appropriate system size for different water levels
  • Watertight, floodable and resistant housing
  • Application in aggressive environments
  • Integrated hydraulic model for precise discharge calculation
  • Measuring range: water level  6 m, 8 m; velocity 0.10 to 15 m/s (depending on the flow conditions)
  • Optional: non-contact measurement of water temperature


Using the radar sensors of the SQ-series various applications in the fields of waste- and process water are possible, as for example discharge measurements in sewer systems, wastewater treatment plants, channel systems, ducts, semi-filled pipes and other technical bodies of water. It is important to monitor the flow rate at the inlet of a sewage treatment plant to be able to regulate the different processes and systems or to allocate the costs in wastewater associations. Similarly municipalities or local water authorities need to measure duration and frequency of rain and flood events in order to manage their storm water channels most efficiently. At central measuring spots in the rainwater sewer system and/or at rainwater overflow basins the amount of water and the discharge rates are determined. The SQ flow meters are perfectly suitable for all these different situations.


Due to its compact design and flexible mounting device, the sensor can be installed very easily. It can be fixed underneath a bridge or at a crossbeam, at the ceiling of closed channels or in a service manhole of sewer channels. Moreover, the SQ is equipped with a mounting cube that allows a vertical / horizontal flexible fixation. Due to the non-contact measuring technology the system can be installed outside of the body of water. This is a big advantage since like this the sensor is prevented from deposits and soiling, what usually happens with submerged devices. Hence, the system remains maintenance-free and easy to access.

For installations in sewer manholes a variable adjustable mounting device can be delivered together with the SQ sensor.


For remote measurement sites without permanent power supply and landline wire connection the SQ can be equipped for remote operation. Including a data logger and data transmission technology (2G/3G/4G modem) together with a strong battery pack the SQ becomes a strong self-supporting and independent system ideally suited for applications in the field or external measurement stations. Optionally the system can be upgraded with a solar panel and a camera for visualisation of the current situation.



  • Dimensions 272 x 153 x 186 mm (1 bracket for pipe with Ø 30 mm)
  • Total weight 1.55 kg
  • Protection class IP 68
  • Power supply 6 ... 30 V DC
  • Power consumption (at 12 V) standby approx. 1 mA; active measurement approx. 140 mA
  • Operating temperature -35° ... 60° C
  • Storing temperature -40° ... 60° C
  • Protection over voltage protection, reverse power protection, lightning protection


  • Measuring range
    • ultrasonic: 0 ... 6 m (type SQ-U)
    • radar: 0 ... 8 m (type SQ-8R)
  • SQ-8R
  • Radar frequency 26 GHz (K-Band)
  • Opening angle 10° (SQ-8R)
  • Blanking distance  0.05 m (SQ-8R)
  • Resolution 1 mm
  • Accuracy  +/- 2 mm (SQ-8R)
  • SQ-U
  • Ultra sonic frequency 50 KHz (K-Band)
  • Opening angle 12° (SQ-U)
  • Accuracy +/- 0,25 % FS (SQ-U)
  • Blanking distance  0.25 m (SQ-U) 
  • Resolution 1 mm


  • Measuring principle Doppler-radar
  • Measuring range 0.10 ... 15 m/s (depending on flow conditions)
  • Accuracy +/- 0.01 m/s; +/- 1 % FS
  • Resolution 1 mm/s
  • Direction recognition +/-
  • Measuring duration 5 ... 240 sec.
  • Measuring interval 8 sec. ... 5 h
  • Measuring frequency 24 GHz (K-Band)
  • Radar opening angle 12°
  • Distance to water surface 0.10 ... 35 m
  • Required minimum swell 3 mm


  • Accuracy +/- 1°
  • Resolution +/- 0,1 °


  • Analogue outputs  2 x 4 ... 20 mA -
    • 1 x for water level; 1 x selectable for flow rate or flow velocity
  • Pulse output pulse per volume (selectable units)
  • Digital Interfaces 1 x SDI-12; 1 x RS 485 or Modbus
    • Transfer rate: 1.2 to 115,2 kBd
    • Protocol: various ASCII-protocols
    • Output: discharge, flow velocity, water level, quality parameter

Additional Info

  • Characteristics: stationary measuring system
  • Features: non-contact measurement

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