Improving water distribution the electromagnetic way

Jon Lawson

Marco Camarena reports on how intelligent process instrumentation helping the supply of a reliable water supply i to maintain public health and fuel a Mexican city’s bustling economy

Nestled along the Zapalinamé Mountains in north-eastern Mexico, the desert city of Saltillo is home to more than 823,000 people and is also a dynamic manufacturing hub, exporting everything from traditional terra-cotta floor tiles to next-generation cars, trucks and home appliances.

A reliable water supply is needed to maintain public health and fuel the city’s bustling economy, but high temperatures and a scarcity of rain make water distribution a challenge – which is why a comprehensive water management system is critical for Saltillo. Innovative and intelligent process instrumentation from Siemens is helping to ensure that the job is done efficiently and safely.

Simplifying a complex process

Aguas de Saltillo is a water utility responsible for supplying drinking water to residential, commercial and industrial customers throughout Saltillo and treating the wastewater. The utility is a public-private partnership between the city and Aguas de Barcelona, a Spanish company dedicated to providing water services across four continents.

Several years ago, Aguas de Saltillo implemented a water network sectorisation (WNS) project to more efficiently manage the complex process of distributing water from multiple reservoirs. The WNS involved dividing the water system into smaller, isolated zones, each with an independent water supply and delimited by boundary valves. Flow and pressure instrumentation was installed at the inlets to serve several important purposes. These include leak detection and control to increase water availability and to provide insight into which sectors prioritise flow recovery actions, pressure level control to ensure safe network operation and maintain customer satisfaction, quantification of water loss stemming from leaks and malfunctioning domiciliary water meters, and recording measurement data to achieve a high degree of transparency regarding sector behaviour.

Remote capabilities in a robust package

Once the WNS was completed and fully operational, Aguas de Saltillo set out to make improvements that would increase network efficiency – which included re-evaluating the mechanical meters they had originally selected to measure flow. The meters were proving overly difficult to calibrate and unable to handle the high mineral content of Saltillo’s hard water, requiring constant and costly maintenance to remove deposits and recalibrate the sensors. Wear on the mechanical parts coupled with rotor and bearing drag in low-flow conditions contributed to reduced accuracy. And the meters required the added expense and effort of installing separate data logging devices to record measurements.

Knowing how important the success of this project was for the city of Saltillo, the water utility initiated an exhaustive search for a higher-performance flow measurement technology. In the early summer of 2012 – and with the help of JAR Electronics, a Siemens Mexico channel partner – Aguas de Saltillo tested its first battery-powered Sitrans F M MAG 8000 electromagnetic flowmeter equipped with an integrated GSM/GPRS wireless communication module and optional radiometric pressure transmitter. Throughout the testing period, the MAG 8000 logged flow and pressure measurements every five minutes and transmitted this data once a day to the MAG 8000 OPC server, which continuously made the information available to OPC clients.

Its IP68 (NEMA 6P) enclosure ensured that the MAG 8000 performed with exceptional accuracy and reliability in all conditions – even flooding caused by rain. The meter also offered Aguas de Saltillo many other advantages, among them:

* Remote capabilities. The GSM/GPRS module provides up-to-date measurement data without users ever needing to visit the site.

* Virtually no maintenance. The meter demonstrates much higher resistance to mineral deposits than its mechanical counterparts with no impact on performance, and also features a long battery life.

* Placement flexibility. The zero-diameter straight-line requirement at the sensor inlet and outlet opens up a much wider range of installation possibilities than previously available.

* Bidirectional flow monitoring. Only one meter is required for measurement in both directions.

* Intelligent operation. The MAG 8000 is capable of leak detection and data logging.

* Low pressure loss. The unrestricted flow tube minimises pressure loss at high flow rates, reducing overall network pressure and helping to prevent leakage from burst pipes and excess stress placed on pumping stations.

A new way forward

When the test was concluded, Aguas de Saltillo made the decision to replace all of their existing mechanical bulk meters with the Sitrans F M MAG 8000 and GSM/GPRS wireless communication module. They standardised on the new meter for use across the various water distribution zones and more than 100 are now in operation, with plans to install additional units in the near future.

According to Juan Diego Bravo Ruiz, chief of telecontrol and telemetry for Aguas de Saltillo, “Including the MAG 8000 with GSM as part of our WNS project has greatly benefited the city of Saltillo. With the consistently accurate flow data we receive from these devices, we’re able to make more educated decisions to better protect our water supply – which means we can better protect our people, too.” 

Marco Camarena is ndustrial Business Development Manager with Siemens’ Process Industries and Drives, Sonderborg, Denmark.

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