Precision flow cuts costs for water authority

To ensure that the water quality standards for which it is responsible are being maintained, Kempsey Shire Council in New South Wales, Australia uses a monitoring station, South West Rocks, equipped with sensors for measuring pH and chlorine.

The sensors used reagents – compounds or mixtures used to test for the presence of certain substnces – in order to establish measurement. Given the age of the system, it was becoming unreliable and required much maintenance. A fall-off in accuracy and the need for more frequent recalibration required increasing levels of operator intervention.

A chance encounter with Bürkert representatives proved fruitful; the company had a new product it was keen to bring to market that offered a potential solution.

Michael Coleman, area sales manager for Bürkert, explained: “We were in the process of looking at potential markets for one of our latest innovations and happened to be talking to representatives at the treatment works. We had an opportunity to discuss the features and benefits of our Online Analysis System Type 8905 for water at a time when they were experiencing a few issues with their own installation.”

Data accuracy and the minimal drift of results is very important in establishing water quality standards and ensuring that local and federal legislation is being met. So, the treatment works installed three of the firm’s water quality analysis systems for performance evaluation.

Flexible installation

One of the first advantages was the compact modular design of the system that makes it very flexible in terms of installation. The component parts consist of an integrated HMI display, input/output modules, sensor cubes and a cleaning system, all of which can be wall or panel mounted, and in Kempsey’s case, built into an existing cabinet. 

Integration helps to reduce the time between a deviation from process parameters and the remedial action required

Once installed, the individual sensor modules or ‘cubes’ are essentially plug and play on a dedicated backplane, which meant the engineers from the treatment works soon had the complete system functioning effectively. A simple process for setting the alarm parameters for each sensor cube, ensures any anomaly in the process is identified quickly.

Instrument technician at the South West Rocks plant, Greg Morrow said: “Since it was installed, there has been no need to recalibrate the chlorine or the pH sensor cubes and their performance has been verified using portable laboratory equipment such as a DPD1 photometer reference test for free chlorine. Furthermore, the sensors’ response time to changes in our process has been virtually instant, far exceeding the performance of the alternatives we looked at.”

Integrated communication

The Bürkert Online Analysis System can communicate with existing control protocols and with personnel both on and off site, ensuring that any deviation from the water quality criteria is notified immediately. This integration helps to reduce the time between a deviation from process parameters and the remedial action required to correct the situation.

The installation has a compact footprint, making it easy to install in existing cabinets and its modular design allows each system to match the requirements of the application. While the initial investment was a higher value, the authority says the ability to maintain accuracy without repeated calibrations has delivered tangible savings in time and money for the water treatment plant.