Thursday 16 August 2018

Cutting Costs by Clamping On – Non-Invasive Flow Measurement for Chlorine Dosing Retrofit

Katronic helps major UK water company to reduce costs by installing a fixed installation KATflow 150 ultrasonic flowmeter

Katronic manufactures clamp-on, non-invasive ultrasonic flowmeters, proven in thousands of applications across a wide range of processes and utilities world-wide. Cost-effective, non-invasive metering offers flexible, accurate measurement without production downtime or engineering work, and Katronic offers equipment for fixed or portable applications with Industrial Ethernet connectivity, high and low temperature performance and EX approvals. 

A Katronic ultrasonic flowmeter has been installed at the flagship water treatment works (WTW) of a major UK water company that treats abstracted water from two reservoirs and serves a population of more than 200,000.

An important part of WTW function is of course to disinfect the flow, undertaken in this plant through chlorine dosing. Water flows through the 830 mm diameter pipeline at an average of 640 litres/sec (45-46 Ml/day), so accuracy in the dosing process is of paramount importance. Originally, the measurement was undertaken by an insertion electromagnetic meter, but this proved to be unreliable, and also leaked. A replacement was required that could give a reliable, accurate and repeatable measurement, of course, but also needed to be installed with minimal disturbance to the process.

The only access to the pipeline was through an inspection hatch into a relatively small pit, so to introduce a large magnetic flowmeter, for example, would have required extensive and expensive civil work, which would have interrupted the process. Other ways of supplying water to the local population may have been required while work went on.

A Katronic KATflow system consists of a compact, wall-mounted, controller that handles signal analysis and communications, and robust transducer pair that clamps on to the pipe to be measured. It was a matter of just a few minutes to access the pit and fit the transducers using a simple clamp and connect them to a KATflow 150 controller, mounted remotely. A key benefit of Katronic systems is the logical and straightforward set-up and programming process, so the system was quickly providing the reliable 4 - 20 mA signal proportional to flow rate that the chlorine dosing system required.

As long as the pipe is full, the system is largely independent of the liquid being measured. The ultrasonic system operates on a 'time-of-flight' principle, comparing the time it takes for a signal to travel upstream to a signal moving downstream and deriving a flow rate from the difference between them.