Dr. Jürgen Skripalle
MANAGING DIRECTOR CENTER OF COMPETENCE AFM
Our DUCTUS solution delivers highly precise flow measurements – even with disturbed or highly fluctuating flow rates. Ideal for hydropower, flood control, large supply lines, and industrial applications. Multiple acoustic measurement paths and advanced signal processing guarantee maximum accuracy and reliability.
Our DUCTUS system was specifically designed for large pipelines where conventional measuring systems reach their limits or are unavailable due to their size. It combines state-of-the-art ultrasonic flow measurement technology with maximum flexibility and the highest level of operational reliability. Whether for consumption measurement or process control in water distribution networks, wastewater treatment plants, auxiliary circuits in industrial applications, or hydropower plants: thanks to flow profile compensation and multi-path ultrasonic measurement, DUCTUS delivers reliable and highly accurate results. In practice, long inlet and outlet sections are rarely available. Valves, pumps, bends, or changing operating conditions lead to swirl and asymmetrical flow profiles. Ductus was developed precisely for this reality – maximum measurement accuracy without flow straighteners, without complex modifications, and without on-site calibration.
With DUCTUS, we rely on a proven technology that has been recognized in the industry for decades and guarantees maximum precision and operational reliability, even in complex measuring points. Thanks to the acoustic measuring paths arranged within the pipe cross-section, the entire velocity profile is recorded, and the flow rate is calculated using special integration methods. The system delivers reliable measurement data and can be flexibly integrated into existing control systems.
DUCTUS, which operates on the principle of transit-time difference, provides a multitude of additional measurements besides flow rate, from which correlations can be identified and new insights gained. The velocity distribution in the pipe can indicate the presence of deposits or calcification, the signal strength suggests the presence of sediment, the speed of sound diagnoses changes in the medium, and the temperature of the medium measured across the pipe cross-section provides important additional information.
Precise flow monitoring is essential in many applications, but fittings and pumps often complicate the measurement process, or the required long, straight pipe sections upstream of the measuring point are not available. This is precisely where DUCTUS demonstrates its strengths, as it captures the entire velocity profile. Its modern, digital signal processing detects even the smallest differences in transit time, ensuring that every last liter of water in a pipe is measured.
Our engineering team supports you throughout the entire project. Whether it's an existing or new measuring point, we ensure that the measuring point concept takes all specific requirements into account. Our experts bring explicit application know-how to the table. Together, we define the optimal installation location, the required accuracy, and, for example, the possible preventive maintenance intervals for the measuring point.
Our engineering team possesses extensive knowledge of fluid mechanics and utilizes state-of-the-art calculation methods, including measurement uncertainty estimation. Computer-aided methods for simulating and predicting flows (CFD) allow us to virtually analyze flow behavior, minimize risks, and reduce costs. During assembly and commissioning, we employ non-contact tools to create highly precise points on the pipe geometry and sensor positions, which are then converted into CAD models. This approach is ideal for ensuring the accuracy of input parameters and for digitizing the project.
Each DUCTUS solution is custom-made for the measuring point and takes into account the specific characteristics of the respective application. Our skilled workers in our modern production facility in Lucerne ensure the highest quality in the device assembly. Upon request, the systems can be separately inspected and approved by independent experts in the adjacent laboratory of Lucerne University of Applied Sciences and Arts or METAS.
The worldwide turnkey installation and commissioning of measuring points in large pipelines and water tunnels is complex and requires extensive experience. Our experts meticulously plan the installation and commissioning and work closely with you. Often, only short time windows are available for installation and every step must be perfect. You can rely on us and our experience.
Ductus integrates seamlessly into your existing system landscape. We use common industry standards for data communication. During commissioning, we ensure seamless data transfer.
DUCTUS contains no moving parts and is therefore maintenance-free. Nevertheless, we recommend regularly checking the sensors, cables, and installation. Here, too, we support you with customized service solutions that ensure continuous operation of your measuring points.
The system offers flexible installation options: feedthrough sensors when the pipe is accessible from the outside, internal sensors for hard-to-reach pipes, clamp-on sensors for non-contact flow measurement and flanged solutions in flexible length and nominal diameter.
Weld-in sensors are preferred for use in pipelines where the pipes are accessible from the outside. If the pipe wall is sufficiently thick, the sensors are screwed directly in. If the wall thickness is thinner, the sensor is mounted using an additional weld fitting into which it is screwed.
If the pipe is only accessible from the inside, the sensors can be installed directly on the inside of the pipe wall. Additionally, all signal cables from the sensors to where they exit the pipe are run in protective conduits to shield them from the high flow velocities.
Non-invasive sensors are attached to the outside of the pipe and measure through the pipe wall. The sensors can be installed and maintained with minimal effort and without interrupting the process.
For use in supply lines with flanged measuring points, a fully integrated Ductus solution is available, which can be flexibly configured in terms of length and nominal diameter. This makes Ductus a particularly cost-effective way to upgrade existing measuring points, especially in existing lines.
Are you interested in our services or another customer segment? We look forward to hearing from you.
Do you have any further questions? Don't hesitate to contact us!
Flow measurement in the penstocks of hydroelectric power plants is challenging: bends, short straight pipe sections, swirl, and changing operating conditions distort the velocity profile and render single-point measurement methods unreliable. Multipath ultrasonic transit-time measurement captures the complete velocity field across the entire pipe cross-section and compensates for these disturbances without flow straighteners or on-site calibration. It also meets the requirements for flow measurement during field acceptance tests according to IEC 60041 and ASME PTC 18. GWF DUCTUS is installed in hundreds of hydroelectric power plants worldwide, including large pumped-storage plants, where precise flow measurement directly determines the calculated turbine efficiency and informs operational and maintenance decisions.
Yes, DUCTUS clamp-on sensors are mounted externally on the pipe and measure through the pipe wall without any intervention in the pipeline. Neither process interruption nor pipe modifications are necessary, making them ideal for retrofitting existing systems. The multi-path clamp-on measurement compensates for disturbed flow profiles and delivers reliable results even where straight pipe sections are limited. GWF DUCTUS supports clamp-on sensors for pipe diameters from DN50 to DN15000, and the GWF engineering team handles site assessment, installation planning, and commissioning worldwide.
Multipath ultrasonic transit-time measurement devices like DUCTUS have no moving parts and require no periodic recalibration. Measurement accuracy is based on acoustic physics and pipe geometry, not mechanical wear. DUCTUS features integrated self-diagnostics that continuously monitor signal strength, correlation quality, and path integrity, detecting drift or sensor degradation before data reliability is compromised. GWF recommends periodic checks of sensors, cables, and installation conditions and offers customized service and verification programs. Where independent confirmation is required, the systems can be cross-checked against portable reference devices or accredited laboratory standards.
Turbine efficiency is derived from precise flow measurement, hydraulic head, and electrical power, and flow rate is consistently the most difficult parameter to determine reliably. Uncertainties in flow measurement directly impact the calculated efficiency and influence operational decisions, contractual warranty testing, and the ability to detect performance degradation before it develops into a larger problem. GWF DUCTUS continuously delivers precise flow data, enabling operators to track efficiency trends, identify performance changes, and make informed decisions regarding maintenance and upgrades.
Most flow meters require long, straight pipe sections upstream of the measuring point to deliver accurate readings: a condition rarely met in real-world infrastructure. Multi-path ultrasonic systems capture the velocity profile across multiple measurement paths and apply profile compensation. This allows them to deliver reliable results even directly downstream of pumps, bends, or fittings, entirely without flow straighteners. GWF DUCTUS covers pipe diameters from DN50 to DN15000 and is used in water supply networks, hydroelectric power plant penstocks, and industrial pipelines where installation conditions are limited and accuracy requirements are high.
In large transmission and penstocks of hydroelectric power plants, leaks and structural damage rarely give any warning. By the time a pressure loss becomes visible at the surface, significant damage has often already occurred. Continuous ultrasonic flow monitoring across the entire pipe cross-section provides the essential data for early detection of anomalies: unexplained flow deviations, sudden pressure-induced velocity changes, or gradual losses that indicate impending damage. GWF DUCTUS is used for both flow measurement and infrastructure integrity monitoring in hydroelectric and water supply lines, where early detection of leaks and pipe ruptures enables timely intervention and reduces operational risk.
The choice depends on three factors: whether the pipeline can be taken out of service, whether external access to the pipe wall is available, and whether the installation requires formal performance verification or contractual accuracy guarantees. Clamp-on sensors are mounted externally without pipe modification and without interrupting the process. They are the practical choice for retrofits, temporary measurements, or situations where welding is not possible. Weld-in (feedthrough) sensors are installed through the pipe wall into the flow, providing the highest signal quality and measurement accuracy, and are the standard for permanent installations with stringent performance guarantees or field acceptance testing according to IEC 60041 or ASME PTC 18. Internally mounted sensors are used for very large pipes where access is only possible from the inside. GWF DUCTUS supports all three configurations on the same transmitter platform, and GWF application engineers help determine the right solution based on site conditions and accuracy requirements.
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