Ultrasound Based Measuring Technique

Ultrasound Based Measuring Technique
Measuring 2D - 3D Velocity Profiles
In Transparent & Opaque Liquid Flows
to Study Lquids & Gas Motions

A Swiss Based Technology

Pioneers of Untrasonic Velocimetry

High precision made in Switzerland

High precision made in Switzerland We develop and produce our technology in a culture renowned for its creativity and pragmatism, designing products that have proven to be precise, reliable and durable over time.

Pioneer of ultrasonic velocimetry

Since 1990 we have been inspired and stimulated by a varied community of scientists and engineers, who bridge research and field applications using our measuring instruments.


Evolving in an international context, we partner with a network of agents active in more than thirty countries, cultivating a close relationship with our users with expertise and experience.

About Met-Flow

Met-Flow is a pioneer in the field of Ultrasonic Velocity Profiling (UVP) technology, developing and marketing ground-breaking instrumentation and software since its foundation in Switzerland in 1990.

Applications fields at a glance

Our measuring instruments can be applied to both transparent and opaque liquid flows, used for a wide range of applications in research laboratories, industrial pilot plants, field surveys, for example for structural design, flow analysis, rheological studies, or even process control.

UVP Concept

Ultrasonic Velocity Profiling (UVP) is a measurement technique based on ultrasound Doppler, to acquire velocity profiles of liquid flows.

Ultrasonic Velocity Profiling (UVP) is a measurement technique based on ultrasound Doppler, to acquire velocity profiles of liquid flows.

By mean of narrow-beam transducers, the UVP system releases ultrasound pulses in the studied liquid, which are reflected by flowing particles, solid or gas. Comparing both emitted and received acoustic signals, shifted in frequency due to the Doppler effect, the liquid velocity can by evaluated at various distances on the transducer measuring axis.

The instruments using this technique, Ultrasonic Velocity Profilers (UVP), can be seen as a kind of sonar combined with speed camera techniques.

Each connected transducer measures a 1D velocity profile on its own axis. A combination of several transducers provides 2D or 3D maps of the studied flow, controlled and synchronized by one single UVP instrument.

As ultrasound travels in most liquids, both transparent and opaque liquid flows can be measured.


  • Spatio-temporal velocity field at high resolutions
  • Non-intrusive measurement
  • 2D and 3D velocity flow field mapping possible
  • Measurement in both transparent and opaque liquids
  • Through-wall measurement possible
  • No calibration required
  • Small dimensions and easy set-up

Contact IIES for a Sales Quote

Our Sales Specialists will be glad to assist you in any inquiry related to Maxar Technologies


Most frequent questions and answers

To measure in air or other gasses is practically impossible with UVP instrument working with high frequency sound fields, as in those media the acoustic impedance is much more smaller than in liquid or solids. Moreover, echo would be generally very weak.

In such case measured profile extends up to the liquid surface, and measurement points above surface are missing. This effect can also be used for surface level measurement. It should be noted however that a reflection from the surface returning to the transducer may under certain circumstances destroy the measured profile. Such returning occurs randomly depending on the condition of the free surface.

In case of circular pipe or square channel it can, through a geometric integration of the velocity profile. If beam incident angle and pipe diameter/ channel width are known, then UVP Monitor can recalculate measured profile directly to through-flow. This is true assuming that the flow is well developed at the measuring position.
Comparative tests has been made with a weight tank calibration system in water, providing error rate from 0.18 % to 0.59 %. Measurement repeatability was also very good.

Yes, this is being performed automatically. Profile measurements are being done repeatedly, results are calculated by local averaging, and at the same time RMS value is also calculated.

The temperature has an effect on the sound velocity. If the speed of sound in the fluid has a strong dependence on the temperature, it has to be corrected. From the practical point of view, the temperature of the fluid affects the condition of mounting a transducer. The present ‘standard’ transducers have the maximum operating temperature of 60°C. If the temperature is higher than this at the place where the transducer is mounted, special care has to be taken, or special high-temperature transducers up to 150°C used.
More importantly, in application of UVP to high-temperature flow fields, it is not the temperature level which might form a problem, but temperature gradient in the fluid. The temperature gradient has an influence on propagation of ultrasound. Ultrasound beam can be bent or reflected a little, unless the beam direction is normal to the temperature gradient. Clearly, UVP can measure velocity profile as long as the liquid includes reflectors, but the position of the velocity profile could be distorted a little.
Up till now, UVP has been used in water with temperature difference of ca. 30°C per 10 cm, and no significant influence on measurement has been found.

The present model of UVP has been developed for flow in such liquids as:
• Water
• Organic liquids: Freon, Petroleum
• Liquid metals: Mercury, Lead-Bismuth-Eutectic
• Ferromagnetic liquid
• Polymeric fluid
• Food materials: Mayonnaise, Ketchup, Coffee, etc.

It takes several microseconds to UVP Monitor to switch from transmitting to receiving mode. This time solely due to electronic switching makes the smallest measurable distance approximately 3 mm from transducer face.

Contact IIES and we will be glad to answer all your questions and inquiries related to UVP and Met-Flow products


A swiss based Ultrasonic Velocity Profiling (UVP)

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