Stationary Ultrasonic Water Flow Meter

The FLUXUS WD Series non-invasive ultrasonic flow meter is the ideal solution for metering points in the drinking water distribution network.

Due to the use of its clamp-on technology, the WD Series does not require any work that affects the integrity of the pipe. This enables a very simple and cost-effective installation of flow measurement points within an existing water supply network.

The FLUXUS WD Series belongs to the most reliable and accurate non-invasive ultrasonic flow metering systems - it even measures flow rates as low as 0.01 m/s. The inaccuracy of other meter technologies, such as magnetive inductive meters, can increase so dramatically in the low flow range, that they are unsuitable for monitoring minimum night flows. But for water suppliers the precise monitoring of minimum night flows is an essential part of their leakage detection activities – and the WD Series is the ideal tool for this task.

There is no method of zero drift correction for our instruments – because they just don’t drift. This also applies to the WD Series that is installed without zero calibration and remains drift-free, permanently. FLEXIM is the only company that accomplishes this, thanks to its unique combination of matched piezo-transducers and advanced factory calibration.

FLEXIM supplies the WD Series with the most robust mounting system on the market. The transducers are fixed to the pipe with broad stainless-steel straps and secured in robust stainless steel housings. The transducers themselves have IP68 protection and reinforced transducer cables. A further unique feature of FLEXIM is that the transducers are connected with permanent coupling pads, instead of coupling gel that can deteriorate or be washed away. All this ensures the durability of the system and makes it suitable for both installations in chambers and buried installations.

The WD meters are available with several transducer types being suitable for a wide range of pipe sizes. The strong signal output and noise suppression technology make it possible to use the WD Series on all pipe materials, even on such challenging ones as fiber-reinforced plastic (FRP) pipes. The outstanding performance of FLEXIM is shown by thousands of references worldwide.


  • Very low installation costs and zero pipe interference
  • Extremely accurate down to flow velocities as low as 0.01 m/s
  • No zero-calibration needed and permanently drift-free
  • Permanent coupling pads
  • IP68 transducers
  • Transducers can be permanently buried (no chamber required)
  • Drift-free measurements
  • Reliable and accurate data
  • Low installation costs
  • Built to last
  • Works on difficult pipes
  • Non-invasive water temperature measurement based on ultrasound
  • Integrated meter verification capability - AMV


Industry Applications

Technical Facts

Pipe material
Steel, plastics, concrete, PCCP, FRP/GRP,…
Pipe diameter range
F532WD: 25mm ... 2000mm
F721WD: 50mm ... 6500mm
Flow channels
F532WD: Single
F721WD: Single or Dual
Temperature Range (pipe wall)
-40°C ... +130°C
Measuring quantities
Volume flow, mass flow, flow velocity
Measurement uncertainty of the measuring system (volumetric flow rate)
±0,3 % of reading ±0.005 m/s
Measurement uncertainty at the measuring point (volumetric flow rate)
±1,0 % of reading ±0.005 m/s
0.15 % of reading ±0.005 m/s
Flow velocity range
0.01...25 m/s
Non-invasive water temperature measurement
Power supply
F532WD: 90…250 VAC or 11…32 VDC
F721WD: 100…230 VAC or 20…32 VDC or 11…16 VDC
Degree of protection
IP66 (transmitter)
IP67 or IP68 (sensors)
4-20mA active/passive
4-20mA HART active/passive
Digital communication
Modbus RTU/TCP

Modbus RTU/TCP
Profibus PA
Foundation Fieldbus
Advanced Meter Verification (AMV)
Additional Information
For more detailed Information please download the Technical Specifications