Entirely non-intrusive, clamp-on ultrasonic flow measurement technology enables precise monitoring of fluid flow through pipes without the need for any pipe modifications. This innovative technology uses ultrasonic transducers clamped onto the exterior of the pipe, sending and receiving sound waves that traverse the pipe’s cross section.
By measuring the time it takes for these waves to travel between transducers, the flow rate can be accurately calculated. This method is especially beneficial for large-diameter pipes, difficult to access installations, and situations where shutting down the system for meter installation is not feasible.
The challenge at a major water treatment facility
At a large water treatment facility in the north of England, accurate flow measurement was critical. Drawing water from the nearby river, the facility operates two cast steel pipes of 1.8 metres and 1.7 metres in diameter to feed treated water into the supply network. The existing wetted inline flow meters, installed over three decades ago, were no longer reliable. But replacing them posed significant challenges due to the size of the pipes and their underground location, making the installation of new electromagnetic flow meters impractical and costly.
Limitations of traditional flow measurement methods
Installing traditional inline or insertion electromagnetic meters would require extensive construction, including the installation of large underground chambers and isolation valves, with an estimated cost far exceeding £500,000. This solution would also disrupt the plant’s operations and water supply. Instead, the engineers explored the feasibility of clamp-on ultrasonic technology, which offered a non-intrusive and more cost-effective alternative.
Exploring clamp-on ultrasonic technology
Emerson’s Flexim clamp-on technology was considered for this application. Suitability was first evaluated using theoretical flow sizing and performance simulations, followed by on-site tests with a portable flow meter. These tests confirmed the theoretical predictions, demonstrating that accurate flow measurements could be achieved without disturbing the pipes.
On-site testing and validation
Despite the old pitted, corroded and uneven pipe surface conditions, the clamp-on ultrasonic system provided high diagnostic measurement quality. The test revealed disturbed flow profiles at the measurement points, a challenge that could be mitigated using 8-path averaging arrangements with four transducer pairs. This approach averages out velocity variations, compensating for cross flow distortions and ensuring accurate volume flow readings.
Implementation of the clamp-on ultrasonic system
Ultimately, each of the two pipelines was equipped with a 4-channel clamp-on ultrasonic system. This setup, featuring 8 sound paths and 4 measuring planes, ensured optimal accuracy and compensation for expected flow profile disturbances. The installation process, performed by experienced technicians, was completed within a day or two, without interrupting the water supply or requiring major construction work.
A cost-effective and accurate solution
The adoption of clamp-on ultrasonic flow measurement has provided the water treatment facility with a precise, maintenance-free, and highly cost-effective solution. The system’s high accuracy and dynamic range allow continuous monitoring and optimisation of water distribution, enhancing the facility’s operational efficiency and ensuring a reliable water supply to consumers.
To find out more about the real-world benefits of clamp-on ultrasonic flow measurement in the water industry, for permanent mains-powered installation, or battery-powered rental meters available from 1 week to longer duration options, contact Andy Hammond – www.emerson.com | flexim-uk@emerson.com | +44 (0)1606 781 420
