Aug 05, 2019

Magnetic Flowmeter Magic

Magnetic flowmeters meet  water & wastewater utility needs

Magnetic flowmeters meet water & wastewater utility needs

Aging infrastructure is not only a problem with roads and bridges; it also affects water and wastewater treatment plants. Many of these plants are at least half a century old, and they also face a similar issue to many other industries: an aging workforce. As this workforce retires, years of skills and knowledge retire them. 

This does not even take into account the increasing demands on water and wastewater treatment due to population growth, especially in already dense urban areas. Add ever more stringent health and safety regulations that impact facilities and their operations, and the problem gets even more challenging. 

The American Society of Civil Engineers gave the U.S. infrastructure a D+ in its 2017 Infrastructure Report Card. This is the same grade it gave just for wastewater. Drinking water received a D. This is close to a failing grade and highlights obvious room for improvement.  


Keep it Flowing

One of the concerns with water and wastewater is accurately measuring flow and knowing when and where problems are developing, all while ensuring the right amount of chlorine is added to kill harmful bacteria. This is where a magnetic flow meter ideally is suited to the task of tracking flow going through the pipes. 

Magnetic flowmeters are accurate and their results are repeatable within set operating parameters. They can work above or below the water line, depending on where they are needed and how their data is collected. 

How Do Magnetic Flowmeters Work?

Magnetic flowmeters operate on the principle of Faraday’s law of electromagnetic induction, named after English scientist Michael Faraday, who studied the effects of magnetic fields on electrical circuits. The basic law of electromagnetism predicts how a magnetic field interacts with an electrical circuit to produce an electromotive force, a phenomenon called electromagnetic induction. 

Simply put, when a conductive object (or fluid) moves through a magnetic field, it will produce an electromotive force (a voltage). The magnitude of the induced voltage is proportional to the velocity of the conductor (or fluid), the width of the conductor and the strength of the magnetic field. By creating a circuit across the magnetic field (through the conductor), the amount of voltage generated by the movement of the conductor can be collected and measured. That measurement is proportional to the velocity of the fluid. In magnetic flow meters, electronics control the magnetic field by supporting a steady current to metal-wound coils, and this is used to measure the induced voltage generated by the conductive liquid. 

Many liquids are conductive, and water with dissolved ionic particles, which can be impurities or chlorine, for example, becomes more conductive depending on the number of particles per gallon. This makes the magnetic flowmeter an effective option for measuring flow in water and wastewater treatment plants. 


Aging on a Budget

In most cases a complete overhaul of a water treatment facility is not feasible. Operations must continue to meet customer needs even if the growing demand places extra stress on struggling systems. One suggestion is to retrofit the system. 

Flow meters often are good candidates for retrofits. By replacing aging meters and their transmitters with modern ones, there are several returns on investment realized in short order. Because the equipment is new and built with the latest technology, they are more reliable with fewer process interruptions, which reduces maintenance expenses.

In a time of rising energy expenses, having more energy-efficient equipment is a benefit, and newer flowmeters can reduce this cost. Smoothly running systems mean a facility can count on improved process outcomes for years to come.

Additionally, many meters now have a transmitter with a digital output. A technician can eliminate manual flowmeter reading by logging them remotely on a laptop, tablet, or smart phone. This brings with it savings in planning and scheduling, as well as associated cost savings. The data are centrally collected and translated into actionable information more quickly, which can make facility operations proactive instead of reactive. 

The Next Generation

With a large portion of the workforce planning retirement, water and wastewater treatment facilities are reassessing their hiring and training strategies, in addition to their equipment. What is the new crop of engineers and technicians taught in school, and how closely does that match with the equipment and processes at a facility? 

While the old guard knows workarounds and patches for aging equipment to keep processes running, new hires are more comfortable with digital systems. How that knowledge gap is bridged will impact a facility, not just today but in the future, as the new hires integrate into the team.

Another often ignored issue to consider is that the younger generation of workers statistically is less inclined to stay in one job for longer than five years, which again may impact the continuity of operations. This is where selecting the right equipment and process control schemes will help a facility plan for and proactively address challenges before they disrupt operations. For example, selecting a magnetic flowmeter with advanced diagnostic software not only provides greater insight into the process, in real time, but also provides a regular snapshot of meter status and health. This is valuable data management can use to predict and schedule maintenance and to anticipate challenges before they disrupt processes. The right devices enable greater process automation, simplification and standardization of work practices, which will help onboard new hires faster and ensure stable productivity in an ever-changing workforce. 


Going Forward

Looking to the future of water and wastewater facility infrastructure needs, it is clear there are many components to consider when planning how best to optimize operations and ensure continuity of processes. No one will dispute investments in critical infrastructure upgrades, as they sorely are needed to meet the ever-increasing demands over the next decades, but they also are necessary to ensure a continual, safe and reliable water supply and waste treatment system.

The option to use instrumentation to remotely monitor processes with advanced diagnostics increases uptime and reduces the need for personnel to physically check each meter. Automation of magnetic flowmeter data collection streamlines operations and provides a centralized data location, which can be used to track operations and meter health, and it can generate audit reports at regular intervals to show the status of facility operations as a whole.   

Critical and targeted investments in components ease the burden of workforce fluctuations and meet infrastructure upgrade needs, and with those investments, a water or wastewater facility can weather the changes and meet the critical demands of water and wastewater treatment. 

About the author

Trever Ball is director of product marketing for Emerson’s Rosemount Magnetic Flowmeter Products. Ball can be reached at