Flowmeters – free surface flows

Ultraflux proposes a complete series of devices for reliable and accurate flow measurement on free surface flows.

Reminder: a free surface flow is a flow where the pressure at the surface of the liquid (usually water) is equal to the atmospheric pressure. In most cases, this concerns natural (rivers, streams, etc.) or artificial waterways (feeder, irrigation, inlet, transport canals, etc.). Pipes that are not filled (therefore not pressurized) are also considered as free surface flows.


To understand the operation of our flow meters for free surface flows, visit our Free surface flow measurement page.

Field of application

Flow and speed measurement using the ultrasonic transit time difference method in free surface flow constructions is the most accurate method available today. Our converters and probes adapt easily to constructions where the width varies from 1 to 500m wide (depending on the site configuration and application conditions).

Typical applications

Flow measurement of:

  • Sanitation network, storm water overflow and treatment plant intakes and outlets,
  • Open or irrigation canals,
  • Natural waterways up to 500m wide (supply of the complete turnkey system).

Our devices

Our products allow you to carry out your measurements with complete confidence and require only minimal maintenance or even no maintenance at all!
Our converters are compact and robust. Our probes are static and a priori maintenance free. If you wish, they can also be installed on rails to facilitate your control or maintenance operations.

The advantages of our products include:

  • Unaffected by downstream congestion,
  • Very wide dynamic flow range,
  • Construction loading possible,
  • No hydraulic calibration,
  • Radio transmission between river banks, etc.

For more information, explore our ultrasound flow meters for open canals (CO from the French “Canal Ouvert”) and rivers (RV):
Uf 811 CO
Uf 821 CO/RV
Uf 831 CO/RV