Clamp-on ultrasonic flow meters provide a non-intrusive method for measuring flow rates in closed pipes.
By utilising transit-time technology, these meters send ultrasonic signals through the pipe wall to detect the flow velocity of the fluid inside.
This technology offers several advantages, including minimal installation effort, reduced maintenance costs, and the ability to measure flow in pipes where inline meters would be impractical.
The evolution of clamp-on ultrasonic technology has led to its increasing adoption for both buried and submerged applications, offering a reliable alternative to traditional flow measurement methods.
Rethinking Buried Flow Metering for Cost-Effective Installations
Historically, burying flow meters has been met with scepticism due to concerns over reliability and maintenance challenges. Water industry professionals recall past issues with buried inline meters, where access and servicing became significant obstacles. However, advancements in clamp-on ultrasonic flow meters have addressed these concerns, making buried installations a viable and cost-effective solution.
By eliminating the need for expensive chambers, bypasses, isolation valves, and supply interruptions, clamp-on flow meters drastically reduce installation costs. Unlike meters that require excavation for maintenance, clamp-on meters can be serviced externally, offering operational flexibility in certain scenarios.
Proven Reliability in Buried Applications
Over the past 10 years, Emerson’s Flexim MCERTS-certified FLUXUS® F721WD clamp-on ultrasonic flow meters have demonstrated long-term reliability in buried installations across the UK and Europe. And countries such as Germany, Austria, and the Netherlands have been successfully deploying buried Flexim meters for considerably longer – decades in fact, further reinforcing confidence in the technology.
The F721WD boasts an impressive Mean Time Between Failure (MTBF) of 36.9 years. When paired with IP68-rated transducers and solid-state transducer coupling pads (eliminating the need for coupling gels or greases), these meters provide long-lasting performance in buried environments. For additional reliability, dual-channel transducer configurations can be utilised, ensuring continued operation even in the rare event of a single transducer failure. And use of Advanced Meter Verification (AMV) offers further measurement confidence and predictive maintenance for buried or submerged meters.
Innovative Installation Methods – The ‘Coffin’ Chamber Approach
One UK water utility, having successfully implemented buried Flexim meters in wastewater applications, has adopted a novel “coffin” chamber design for clean water network installations. This cost-effective approach involves installing the meter within a compact, excavated pit, surrounded by a reinforced chamber, and then backfilling the area. The chamber is capped with a cast-iron cover, creating a robust, low-cost installation solution that maximises available budget allocations.
IP68 Flow Meters for Submerged Installations
In addition to buried installations, IP68-rated transducers enable clamp-on ultrasonic meters to function reliably in submerged environments, such as flooded chambers or pits. The use of solid fluoroelastomer coupling foils ensures high durability and zero maintenance requirements, eliminating concerns associated with traditional grease or gel-based coupling methods.
The evolution of clamp-on ultrasonic flow measurement technology has transformed the feasibility of buried and submerged flow meters. With proven reliability, cost-effective installation methods, and minimal maintenance requirements, modern IP68-rated clamp-on meters provide an ideal solution for water and wastewater applications. As more utilities seek to optimise costs without compromising performance, this technology is set to play an increasingly vital role in flow metering strategies through 2025 and beyond.
