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Improved Flow Measurement Through Multiple In-Pipe Readings

Source: McCrometer, Inc.

A combination of water scarcity and the desire to provide exceptional service has driven water utility managers to focus more than ever on acquiring accurate, real-time insight into their distribution systems. Flow measurement is at the heart of this exercise.

Operators face a natural hurdle, however, when using traditional center-line electromagnetic flow meters, which don’t account for velocities that vary across a pipe. Fortunately, a solution has emerged to address the issue.

McCrometer's FPI Mag®, an advanced electromagnetic flow meter (or “mag meter”), is designed with multiple electrodes that account for velocities at different points within a pipe. As a result, it can provide more accurate flow measurement. Because readings are being captured at different points, the FPI Mag can also be placed much closer to something that causes a disturbance in the flow — such as a bend, swirl, or gate valve — with significantly less impact on its accuracy.

The number of global FPI Mag — which stands for Full Profile Insertion Mag meter — installations continues to grow. The technology can be used at municipal water treatment plants and for almost any industrial application that uses water, such as cooling towers and chillers, and is ideal for capital or maintenance projects as well as retrofits.

Building A Business Case

Water utilities that select FPI Mag meters can save as much as 45 percent, compared to traditional electromagnetic flow meters, when total ownership costs are taken into account. That’s because the FPI Mag doesn’t require the heavy equipment and labor required during a typical full-bore, flanged meter installation. In other words, there’s no need to build a chamber or other infrastructure, then hire a crane and operations staff to put the meter in place.

As long as the FPI Mag meter can be attached to the pipe, if a tapping point is available or can be installed there is no need to cut into the pipe, install flanges, or shut down water. This simple hot-tap installation means the meter can be installed without interrupting service. Avoiding both a shutdown and construction of a bypass are significant benefits.

Engineering a ball valve onsite with the FPI Mag does come with a cost, but it is significantly lower than the cost to create a chamber for a traditional valve.

Behind The Technology

The FPI Mag is available in battery- or solar-powered options for forward sensing, enabling installation in remote applications without access to power. It can also be applied to other never-before-metered sites because it doesn’t require construction of a large chamber or lots of infrastructure.

Through a variety of outputs, the FPI Mag offers flexibility to operators. This includes a Smart Output option to connect to AMI/AMR systems through an encoded digital output as well as a standard 4-20 m-A output option to connect to a SCADA system or GSM/GPRS datalogger.

The FPI Mag is a single-piece design with no moving parts. The multi-electrode flow sensor contains nothing to wear or break and is generally immune to clogging by sand, grit, or other debris.

Other key FPI Mag specifications include:

  • Available with forward-flow only or bidirectional measurement;
  • Can fit line sizes from 4” to 138”;
  • Robust construction — The sensor body is made from heavy-duty 316 stainless steel for maximum structural integrity and is hermetically sealed and protected by NSF-certified 3M fusion-bonded epoxy coating; (meter itself is fully NSF-61 & NSF-372 certified); and
  • Meets or exceeds industry standards of 0.5 percent accuracy with third-party testing verification.

Case Study: Lagos, Nigeria

Nigeria, one of the more affluent African countries, touts a mature water network. Lagos itself has multiple water treatment plants providing clean water to approximately 27 million people in the greater region.

Despite a solid track record of service, the Lagos water utility had been struggling to get the insight it needed to track water in the distribution network. Water officials wanted to install measurement systems across the network of existing pipes — some of which are quite large in diameter — to gather critical information. However, the cost of digging down to reach the pipes and install massive chambers for traditional full-bore electromagnetic flow meters was prohibitive.

The utility also wanted accuracy of 0.5 percent, not the 2.0 to 5.0 percent offered by traditional meters.

In 2017, through a consultant, the Lagos water utility approached McCrometer in its search for alternative solutions. With all of the utility’s needs taken into account, and because the Lagos water system was adept at using advanced tapping technology for its analytical measurement probes, it was determined that McCrometer’s FPI Mag provided the best solution.

McCrometer and the consultant surveyed 10 initial trial sites on various pipe sizes, which included different degrees of difficulty and accessibility. Using information collected from the survey, McCrometer manufactured and shipped the units to Nigeria within 10 weeks of the order being placed, then relied on its representative in South Africa to oversee the install and commissioning process.

Each installation took approximately 30 minutes with just two engineers. Full-bore meters, by comparison, would have taken a half day to a full day of labor with a larger crew and a significant amount of equipment.

The first set of units have been installed for nearly a year. McCrometer worked with the Lagos water system to survey sites for 40 more units, which should be installed by the end of 2019, and the program calls for approximately 150 additional units by the end of 2021. Maintenance on the units — removing each to clean electrodes — is scheduled for every other year. Meters being used for raw water will be cleaned on an annual basis. Cleaning and maintenance only take about 10 minutes per unit.

By all accounts, the early results of the FPI Mag project in Lagos have been impressive. Being able to identify the precise flow within different areas of the distribution system at different parts of the day is allowing water managers to understand the “where” and “when” of demand that is resulting in water scarcity issues. This is information the utility didn’t have until now.

Armed with the data, the utility now has the ability to better manage the system. It can be proactive through actions such as changing a valving arrangement to supply more water to certain parts of the city.

What’s impressive about the team operating the water system in Lagos is its progressive attitude and patience, according to Tim Door, an international sales manager for McCrometer.

“They are closely watching what other companies and water systems have been doing in flow measurement,” Door said. “They looked to the mature programs that have gone into systems in a variety of countries and are avoiding mistakes made during those implementations. They want to be a leader and rely on strong collaborations to achieve this.”

In addition to the Lagos installation, a variety of systems across the globe have adopted the FPI Mag with success, including the City of Geneva, OH; Pernambuco, Brazil; the City of Detroit, MI; and Seattle Public Utilities. The FPI Mag has also been successfully installed as part of numerous industrial applications such as cooling towers at a large oil and gas refinery in the Southern U.S. and an island power plant.

McCrometer’s FPI Mag is emerging as a cost-effective solution for water utilities and industrial operations seeking to improve system management by getting a better grasp of their flow measurement.  The key to evaluating the FPI Mag compared to other electromagnetic flow meter technology is accounting for the total ownership costs as well as factoring in accuracy improvements and additional benefits.


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