Clamp-on ultrasonic flowmeters deliver concrete flow measurement solution

Perceived by many water companies to be an incredibly challenging, if not insurmountable measuring task, clamp-on ultrasonic flow measurement is offering a straightforward, non-invasive and robust solution to the problem of flow measurement through concrete pipes.

A task that would normally require expensive and substantial works, monitoring flow in Prestressed Concrete Cylinder Pipes (PCCP), or ‘Bonna’ pipes, consisting of a concrete core, a thin steel cylinder, high tensile prestressing steel wires and a mortar outside coating, is made possible and cost effective with powerful clamp-on ultrasonic flowmeters that can penetrate the walls of even the most difficult pipes of complex, multi-layer construction.

These low-frequency and high-amplitude transducers are capable of sending and receiving signals through the many layers of PCCP pipes, maintaining ample signal quality for exact and reliable flow measurements. Ultrasound signals are sent at 1000 times per second and evaluated by a highly sophisticated digital signal processor that calculates time difference based on cross correlation. This ensures exceptional noise suppression and delivers highly accurate data, even on challenging pipes.

FLEXIM recently completed a successful flow measurement task on concrete reinforced PCCP pipe, for a UK water company that supplies 4.6 million households and businesses. The application was Demand Side Response (DSR), with measurement on a 42” pipe, with a bi-directional flowmeter used. Typical maximum flow = 82Ml/d, minimum flow = 10Ml/d.

Accurate measurement of raw sewage through large concrete pipes

Able to offer non-invasive solutions around the globe, FLEXIM also carried out successful flow monitoring for a major water treatment plant operator in the US. Struggling with the failure of several insertion flowmeters and looking for a more economical alternative, they decided to investigate the idea of clamp-on ultrasonic metering, as they were already familiar with this non-invasive technology and had used it on various pipe materials in the past. However, they needed proof that it would work on concrete.

Full bore and insertion magnetic point velocity flowmeters were once the only option for measuring flow through concrete pipes. Replacing old insertion meters is expensive and resource-intensive, involving service interruptions and possible harm to the pipe’s structural stability during installation. And because insertion meters are exposed to the flow of material in the pipe, there is considerable cost embedded in their design. They also require significant maintenance.

A key advantage of clamp-on ultrasonic technology, is that it can be tested for suitability before permanent installation. So following tests of multiple locations and pipe materials, including HDPE, Ductile Iron, and Precast Steel Reinforced Concrete Pipe (PCCP) with a 7 inch wall thickness, results were so accurate, that every time an insertion meter fails on concrete pipes, the operator now simply replaces it with a FLEXIM clamp-on ultrasonic flowmeter.

Waterproof, accurate and reliable clamp-on measurement solution

Undeniably precast concrete pipe presents a major challenge for any flow measurement technology. But thanks to powerful clamp-on transducers and sophisticated evaluation technology, ultrasonic flowmeters from FLEXIM are able to deliver accurate and drift-free flow measurement data. All with an IP68 waterproof protection rating.



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