SDM Comparison Test in France

Measuring Task

Density determination of a water/solids slurry.

  • Pipe diameter: 300 mm (12 inch)

  • Pipe material: Carbon steel alloy (ASTM A53)
  • Solids: 0 – 10 wt%
  • Density: 1.015 – 1.060 g/l
  • Temperature: 4°C – 8°C (39°F – 46°F)


A French electricity company is using water from an uphill reservoir for power generation at one of their hydroelectric power plants in France. For maintenance, sediments are dredged from the uphill basin and transported to the river downhill. A certain water/solids balance is needed to prevent accumulation of sediment in the flow from the power plant to the river. Also, wear caused by solids on the turbine of the hydro plant has to be prevented.

Instrument used


The contractor invited four suppliers of density meters to prove and validate their density measuring methods. These suppliers are using different technologies to determine the slurry density, done by the measurement of:

  1. Radiation (Nuclear)
  2. Acoustic impedance (Ultrasonic)
  3. Electrical conductivity (Tomography)
  4. Force and acceleration (Mass/volume)

One of the invited suppliers canceled their participation in the test in advance, so three technologies were compared. This was done during a period of four weeks in which the data of each measuring instrument were collected. The image below shows the configuration of the density meter test. The Rhosonics density meter is installed in a metal pipe piece designed for this application.



After four weeks of evaluation, the Rhosonics SDM Slurry Density Meter was chosen as the winning technology. This choice was based on the accuracy and stability of the measurements, but also on the easy installation and short calibration compared to the nuclear and tomography devices.

The Rhosonics density meter contributes to:

  • Prevention of plant shutdowns caused by sand accumulation in the flow to the river
  • Prevention of wear on the power turbine caused by the water/solids slurry
  • Improvement of dredging efficiency
  • No nuclear source, so no costs for licences, permits or specialized personnel

You can read the whole story in the case study. Click on the images below to download the case study in the prefered language.




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