Building Intelligence into Water Metering

Transcription

1 Building Intelligence into Water Metering WPW-WAT White Paper NEW TECHNOLOGIES CAN REDUCE ENERGY CONSUMPTION AND OPERATING COSTS FOR WATER UTILITIES, WHILE IMPROVING REVENUE AND PERFORMANCE. Water utilities are under pressure due to the rising cost of labor and energy and are focusing their attention on improving operational efficiencies. With new choices in flow measurement technologies, utilities can improve cost and gain revenue advantages from advanced meter technologies that: Capture more revenue by accurately measuring a wider range of high and low flows Reduce the cost of owning and operating the meters Lessen energy consumption over the life cycle of the meter Reduce water loss, wasted energy and repair costs through superior leak detection and by proactive notification of trouble conditions HOW TRADITIONAL WATER METERING TECHNOLOGIES MEASURE UP Water meter measurement technologies fall into two broad categories: Displacement meters that have an internal measuring element of a known size or finite volume that rotates due to pressure differential and totalize the finite volume into total volume. Velocity meters that measure the velocity of flow through a chamber of known cross-sectional area and then converts the speed of flow, using the known area, into the volume. The right metering technology for a utility customer depends on the type of water, forecasted flow rates, accuracy requirements and cost. Flow measurement technologies in general use today have been well accepted and widely deployed, but they have some limitations. Better options are now available and it s time to take another look at the business impacts of legacy metering technologies. Let s take a look at the most prevalent metering technologies in the field, and the advantages and Disadvantages of each. The positive displacement (PD) meter is the most common type of meter in use today. In a PD meter, water physically moves the measuring element in direct relation to the amount of water passing through the meter. The piston or disk moves a magnet that drives the meter s register. Advantages: PD meters are generally very accurate at the low to moderate flow rates typical of residential and small commercial customers. These meters are widely accepted and perceived to be more durable than many other types of meters. Disadvantages: In order for a displacement meter to significantly increase its accuracy, the clearances between the measuring volume and the vessel must be reduced; this makes it susceptible to debris. Additionally, as the water volume is increased, the costs to make a piston meter large enough to handle these flow rates increases dramatically. Velocity meters use ports of known size to create a jet of water against an impeller. The impeller rotates in relation to the velocity of water flow. Advantages: Velocity meters are accurate at low flow rates (although PD meters are generally more accurate at low flow rates), typically handle large flows of water and are less susceptible to jamming. Turbine meters, a type of velocity meter, can accommodate higher flow rates with less pressure loss than PD meters. Disadvantages: Performance is not linear across the flow range and generally not as accurate as a PD meter at the very low flows. Fluidic oscillator meters measure the frequency with which a fluid entering the meter attaches to one of two opposite diverging side walls and then the other, due to the Coanda effect, the tendency of a fluid jet to attach itself to a nearby surface. Advantages: This technology measures only the flow of water, so it is not affected by the presence of air in the water system. With no moving parts in the measuring chamber, it can be used where sand and grit are present in the water. Disadvantages: This technology typically struggles at low flow due to the need to have a minimum flow rate, given a specific vessel size, for the coanda effect to start. 1

2 Ultrasonic meters use an ultrasonic transducer to send sound waves upstream and downstream through the water, the difference of which is used to determine its velocity, which is then translated into a measure of water volume. Advantages: There is no measuring element hindering the path of water flow, so pressure loss is not a concern, and there is no reduction of accuracy over time. Disadvantages: Ultrasonic meters require sound, and sound requires power. The high sampling rate required for high accuracy (nearly continuous sampling) produces a heavy power drain. To conserve power and battery life, the sampling rate can be reduced and the periodic measurements averaged, but accuracy suffers, especially at low flow rates. Compound meters have two measuring elements: a turbine to measure high flows and a smaller element, typically velocity or PD, to measure low flows. A check valve regulates flow between the two metering chambers. Advantages: This meter can be used where flow is highly variable: high enough to require a turbine meter but too low to be accurately registered. Disadvantages: Although compound meters offer the benefits of two metering technologies, they carry the potential for clogging at low flows. Moreover, the use of two measuring technologies increases complexity and service requirements. Magnetic flow meters are based on Faraday s law of induction: the induced electromotive force (EMF) in any closed circuit is equal to the time rate of change of the magnetic flux through the circuit. In simpler terms, the meter measures an electrical signal that is produced when ionized water flows through a magnetic field. The faster the water flows, the more voltage is created and measured. Voltage is linearly proportional to speed; as water speed increases, voltage increases and the measure of volume increases. Advantages: Since mag meters have no mechanical measuring element inside the flow chamber, there is no reduction in accuracy over time; there is linear performance over the flow range. These meters maintain accuracy at both forward and reverse flow directions. Disadvantages: In traditional mag meters, creating the magnetic field and sustaining the right electrical environment for accurate readings requires a controlled magnetic field and considerable amount of energy. REDEFINING THE TECHNOLOGY OF WATER METERING Until recently, there has been little advancement in metering technology. Water meters have been quiet workhorses, operating for decades without fanfare, while dramatic technology leaps have been made in other areas, such as AMR and AMI for remote meter reading and monitoring. In 2008, Sensus introduced groundbreaking new metering technologies for commercial and residential applications. Floating Ball Technology (FBT) for high-flow commercial and fire service metering Sensus patented floating ball technology (FBT) is a unique variant on turbine metering concepts that significantly reduces pressure loss and virtually eliminates component wear while improving accuracy across an extended flow range. In a meter equipped with floating ball technology, the measuring chamber includes a ball-shaped, turbine impeller that floats between axial bearings. As water passes through the meter, the impeller rises from the bearings and rotates in the water. Embedded rotor magnets deliver signals to an ultra-sensitive register pickup probe. As flow increases, the impeller centers itself and literally floats inside the measuring chamber. The thermoplastic ball is virtually weightless in water, so it begins moving with very little water flow or force through the meter. As a result, this type of meter can accurately record very low flows as well as support extended high flow rates all with practically no friction or wear. Figure 1. Floating Ball Technology The lightweight, thermoplastic floating ball is sensitive to very low water flows. Sensus innovative, floating ball technology is currently available on the following meters: Sensus OMNI T2 meters for applications that in the past would have used traditional turbine meters Sensus OMNI C2 meters for applications where a compound meter would have been used Sensus OMNI F2 meters for fire line meters OMNI large water meters from Sensus are the most technologically advanced commercial meters on the market today, based on known performance parameters against other meters of the same class. 2

3 Figure 2. Sensus OMNI meters for commercial and industrial applications The only meters on the market that use Floating Ball Technology Remanent field technology for residential water metering Remanent field technology, in conjunction with magnetic metering technology, requires far less energy than traditional mag meters and permits much greater accuracy, even at intermittent or very low flows. A traditional magnetic meter uses electrical current flowing in a drive coil to create the magnetic field, which requires a lot of energy. Remanent field technology also uses a pulse of current in a drive coil to magnetize a small piece of magnetic material. With remanent field technology, the coil set constantly maintains power while periodically flipping. This keeps electrical noise low, and allows for accurate measurement of lower water flows. Uses less power. Normal mag meter coil sets consume a lot of power. Remanent technology, with its low switching rate and patented electrodes embedded in the flow tube, maintains a magnetic field without continuous battery drain. Remanent field technology is only available on Sensus iperl systems for residential and small commercial applications. It is designed for any application where PD or multi-jet meters would have been used in the past. It is particularly well-suited for settings where sediment and sand are present in the water, where customers have fire sprinklers or other mission-critical water services, or where well water is being metered. Figure 4. Sensus iperl Water Management System The only meters on the market thata use Sensus-patented Remanent Field Technology Figure 3. Faraday s Law in Magnetic Meter Technology This new technology enhancement differs from traditional magnetic meters: Captures lower flows. As water flow slows down, the voltage signal is reduced and could be lost in the electronic noise. Remanent meters periodically reverse or flip the magnetic field, thereby cancelling out the noise, to record very low flows that other magnetic meters cannot measure. Measures intermittent flow:. Because the magnetic field is held constant, there are no gaps in measurement. This is a significant advantage for residential settings, where water flow can be intermittent. REDEFINING THE ECONOMICS OF WATER METERING New metering technologies offer tangible and immediate business benefits to utilities. With meters using floating ball technology and/or remanent field technology, utilities can now: Capture more revenue by accurately measuring a wider range of high and low flows Reduce the cost of owning and operating the meters Reduce energy consumption over the life cycle of the meter Reduce water loss, wasted energy and repair costs through superior leak detection and by getting early notification of trouble conditions, when connected to an advanced metering infrastructure (AMI) communications network. Capture more revenue by accurately measuring a wider range of high and low flows Preventing nonrevenue water loss caused by meter inaccuracy can deliver meaningful new revenue and more equitable customer billing. In light of these benefits, utilities may want to make low-flow and high-flow accuracy a key consideration in selecting meters for initial installation or replacement. Accuracy in Sensus OMNI meters. Because even the slightest amount of water will cause the lightweight impeller to move, 3

4 floating ball technology meters can measure flows 50 percent lower than the lowest flow captured by traditional turbine meters. For example, a 2 OMNI T2 meter can easily measure flows as low as 1.5 gallons per minute. Floating ball technology also enables the OMNI meter to register reads at higher flow rates than any other turbo meter currently available. The OMNI s enhanced flow range also means that the meter can be installed in areas where compound meters were previously the norm. Figure 5. Accuracy curves for representative OMNI meters Accuracy in Sensus iperl systems. Because meters utilizing remanent field technology measures intermittent flow, they are far more accurate than traditional mag meters, which are typically configured to sample at intervals and average the results (continuous sampling in mag meters is possible but requires undue amounts of power). Compared to traditional PD meters, iperl systems can measure to a 20 percent lower flow rate. They are also built to withstand high flows while maintaining measurement accuracy, enabling the capture of 100 percent of water flow. Unlike PD meters, iperl systems have no mechanical parts to wear out and degrade accuracy over time. In addition, the design and smooth bore of the flow tube inhibit the formation of scale that may also affect accuracy. Figure 6. Accuracy curves for representative iperl systems Reduce the cost of owning and operating the meters. New Sensus metering technologies are designed not only for high metering accuracy but also for lower total cost of ownership than traditional meters less costly to install, operate and maintain. Easy installation. Sensus OMNI meters and iperl systems are built to standard laying lengths, making them easy to retrofit into existing water distribution systems. Long battery life. The lower power consumption of iperl systems reduces costs and significantly extends battery life. OMNI register batteries are warranted for 10 years, iperl register batteries for 20 years. Simple maintenance. There is only one moving part in the measuring chamber of an OMNI meter, none inside an iperl system. Design simplicity means fewer individual components to maintain. Long meter service life with lifetime accuracy. In many traditional meter designs, such as the PD meters that are used in most residential and small commercial settings, friction and wear on mechanical parts affects accuracy over time and shortens useful service life. New Sensus technologies operate with virtually no friction and wear. The impeller in an OMNI meter floats in the water. The flow tube in an iperl system has no mechanical parts to degrade or jam. No repair is required. Wider range of accurate measurement. iperl and OMNI products allow utilities to capture a wider range of water, from low flow to high flow, while meeting AWWA accuracy requirements at all flow rates to ensure all water usage is measured and accounted for. Reduced labor cost. Besides reduced service/maintenance, Sensus OMNI meters and iperl systems are compatible with industry-standard AMI systems, such as the Sensus FlexNet communications network. Utilities that choose to use these meters in AMI arrangements can eliminate the labor and fleet costs associated with walk-by or drive-by meter reading. Reduce energy consumption over the life cycle of the meter. The Sensus iperl systems and OMNI meters offer a number of benefits that reduce energy consumption over their total lifecycle. iperl systems feature a lead-free construction, comprised solely of composite materials. These materials are much lighter than their bronze counterparts and require less energy to manufacture and ship. Historically, water utilities sent meter readers to customer sites to visit the meter and record how much water was consumed. Automatic meter reading (AMR) streamlined that task by enabling meters to be electronically read from nearby, such as from a vehicle driving by the customer location. These approaches are simple but resource-intensive; meter readers still have to drive vehicles around the served area. Fixed wireless communications the hallmark of advanced metering infrastructure (AMI) enables meters to be read and even monitored and managed from a remote, central location. 4

5 This capability eliminates the need to send a fleet of vehicles out into the service area which in turn reduces fuel consumption and greenhouse gas emissions. Remote wireless communications also enable the water meter to deliver near-real-time information about peak flow, total volume and other conditions to support proactive planning and better business decisions. Sensus OMNI and iperl technologies are compatible with industry-standard AMI systems, including the Sensus FlexNet network. Utilities can link these products to an AMR /AMI system, supervisory control and data acquisition system (SCADA) system (OMNI meters only) or other types of distribution monitoring systems. A key advantage of OMNI and iperl technologies is that they have little effect on water pressure, because there is little resistance in the flow tube. For example: At 1000 gallons per minute (gpm), the head loss for a traditional turbine commercial/industrial water meter can range from 12 to 17 psi, compared to 6.4 psi for a 4 OMNI F2 meter. For a 4 OMNI T2 meter, even with a strainer in place, pressure loss is negligible for flows up to 1000 gpm, then only 4 psi at 1500 gpm and approximately 8 psi at 2000 gpm. For residential metering at 20 gpm, the head loss for a traditional PD meter is just over 5 psi; it is less than 3 psi for an iperl system. By reducing pressure loss 40 to 50 percent relative to traditional meters, utilities spend less to achieve acceptable water pressure at customer premises. For systems with elevated storage tanks/towers, reduced pressure loss at the meter makes it possible to sustain customers water pressure with far less water in storage. For pumped systems, less resistance at the meter level simply means less energy required to push water through the system. Reduce water loss, wasted energy and repair costs through superior leak detection and by getting early notification of trouble conditions. Intelligence in the meter enables utilities to be proactive instead of reactive. With remote notification of leaks, tampering, out-ofthreshold operating conditions, low battery and more, utilities can: Alert customers to an issue before the customer is aware of it or before any damage occurs. Quickly identify, troubleshoot and resolve field issues. Globally, water is a precious commodity, to be used and conserved wisely. Leaks in the water distribution system or at customer sites represent not only lost water, but wasted energy to pump it for no purpose. Traditional turbine and PD meters the most common meter types in commercial and residential applications, respectively do not do a very good job detecting and measuring ultra-low flows. Even if they are equipped for ongoing AMI communications, they could miss the very low flow levels that signal an insidious leak. In contrast, new Sensus meters are extra sensitive to low flows and are therefore more reliable for detecting and reporting leaks. Leak detection with Sensus OMNI meters. Because even the slightest amount of water will cause the lightweight impeller to move, Floating Ball Technology meters can measure flows significantly lower than the lowest flow captured by traditional turbine meters. For example, a 2 OMNI T2 commercial/ industrial meter can easily measure flows as low as 1.5 gallons per minute. Leak detection in Sensus iperl systems. Compared to traditional PD meters, Sensus iperl can measure accurately to a 20 percent lower flow rate, as little as 0.03 gpm. If the flow doesn t stop over a configurable time period, the system assumes it to be a leak and reports it as such. The OMNI features an all-electric register that enables a utility to program detailed settings for recording data that can be used for more intelligent planning. In addition to low-battery alarms, the OMNI can record 31 days of flow history. The iperl offers a sophisticated suite of 14 alarms, some of which are unique to iperls that are communicating via Sensus FlexNet AMI system. Application alarms can detect reverse flow, tampering, empty pipes and leaks, battery life and AMI connectivity allows utilities to be informed of these events in real time for faster resolution and improved customer service. Additional condition monitoring alarms gather data that can be analyzed to detect premature failures and if there is an incident likely to impact the meter s accuracy, preserving revenue. Figure 7. Pressure loss in representative OMNI meters and iperl systems 5

6 SUMMARY OF BUSINESS BENEFITS Water meters, largely unchanged for decades, have historically been viewed as just a utilitarian component in the water delivery system. Now, new flow measurement technologies offered the opportunity for meters to deliver real business benefits cost savings and new revenues as well as competitive differentiation. For water utilities, Floating Ball Technology and Remanent Field Technology: Drive additional revenue by measuring at flow rates percent lower than current products on the market can measure Sustain high accuracy over their operating ranges and throughout the life of the meter, due to designs that reduce or eliminate friction and wear Reduce the energy costs associated with pumping, due to reduced pressure loss at the meter Streamline and reduce the costs of installation, operation and maintenance For utility customers, these new meter and AMI technologies: Improve water system performance and reliability, thanks to early notification to the utility of trouble conditions such as leaks, often before the customer has even realized a problem exists Enable more equitable and flexible billing options, due to higher meter accuracy, continuous measurement and compatibility with AMR/AMI systems for on-demand data ABOUT SENSUS Sensus is a leading utility infrastructure company offering smart meters, communication systems, software and services for the electric, gas, and water industries. Sensus technology helps utilities drive operational efficiency and customer engagement with applications that include advanced meter reading, data acquisition, demand response, distribution automation, home area networking and outdoor lighting control. Customers worldwide trust the innovation, quality and reliability of Sensus solutions for the intelligent use and conservation of energy and water. Learn more at To follow Twitter updates from Sensus, please visit For more information, visit us at sensus.com Six Forks Road, Suite 700 Raleigh, NC