About the author: Gerard van Boven is senior product manager, electromagnetic flowmeters, for KROHNE Inc. For more information, please contact [email protected] or 1.800.FLOWING.
Gerard van Boven
undefinedWater is a scarce and precious commodity. Worldwide, the competition between domestic, commercial, industrial and agricultural sectors for clean water is intensifying and putting enormous pressure on freshwater resources. As a result, the price of water is increasing throughout the world. Pricing and metering are seen as important tools for more efficient use of water and water conservation. Metering also enables billing or revenue collection based on actual water consumption. The more valuable water gets, the more interested the market becomes in the accuracy and reliability of water meters.
Bulk Metering
Commercial and industrial water meters, or bulk meters, are used for monitoring and billing the water consumption of large cold water users. Large consumers of water include industrial plants, office buildings, hospitals, schools, hotels and apartment buildings. Although industrial and commercial customers often comprise a limited number of customers compared to the number of residential customers, they consume a relatively large share of the total water supplied by a water company and thus a significant part of their revenues. Water companies are setting up separate divisions for industry water services.
For various reasons, mechanical meters once dominated the water meter market for measuring drinking water of residential and commercial users. Electromagnetic water meters, however, have gained market share for bulk measurements because of their high accuracy and the ability to maintain accuracy over time.
Contrary to many other industries in which electromagnetic, ultrasonic and mass flow-meters have the highest growth rates and large market shares, in the drinking water market the use of mechanical meters has remained very popular. One reason why is that mechanical meters do not require mains power, do not require an electrical infrastructure and continue to function in the event of a power failure.
Cabling costs can be high, especially in remote areas and highly populated areas, and are subject to tampering. With the introduction of battery or solar power technology for electromagnetic water meters, this problem has been overcome.
Installation & Maintenance Costs
Pricing is always an important criterion in the selection of a meter. Increasingly, companies focus on the total cost of ownership, including the purchase price, the costs of inaccuracy, under-registration and installation and maintenance costs.
Electromagnetic water meters are obstruction free and operate without moving parts; therefore, they maintain accuracy over time and help reduce time spent on routine maintenance and service activities. The economical and technical lifetime of an electromagnetic water meter can be up to 20 years or more. There is no need to replace the meter or its internal parts as with turbine meters. Because they are obstruction free, another important benefit is that they cause negligible pressure loss in the distribution network.
The differences in water use between day and night can be huge, and ideally, water meters should be able to measure low and high flow rates with high accuracy.
Market Developments
One major trend in water metering is data logging and remote reading of measurement data. Facilitating automatic data reading and collection is especially beneficial for water meters distributed over wide areas or located in remote areas or places that are difficult to reach (e.g., underground installations in busy city centers or in areas in or close to buildings that are often closed or locked).
KROHNE's battery-powered Waterflux 3070, which has a high accuracy over a large turndown ratio combined with a long battery life, is a stand-alone water meter that can be equipped with a data logger and wireless communication (GSM) modem. The optional module also operates on batteries and can be connected to any GSM network. The data logger and GSM module improve the efficiency of cold water distribution networks by continuously reading the connected water meters and transferring the data to a SCADA system. Wireless meter reading saves the high costs of manual reading and can be used to check the water meter condition and rapidly identify meter failure, vandalism or tampering.
Underground Installation
KROHNE’s Waterflux 3000 sensor is approved to IP 68, which allows the meter to be submerged in water, to be buried directly underground or be installed in small measurement chambers underground—all leading to significant installation cost savings. Further savings in installation costs are possible because of the solution’s limited inlet and outlet sections. An inlet of only 3D and outlet of 1D is unique in the market and allows for installation in small spaces. Additionally, straighteners are not required as a result of the technology’s innovative construction.
With its unobstructed flow sensor, a strainer or extra cabling are not required because it runs on batteries and it measures forward and reverse flows with the same accuracy. Engineering has also become much simpler, as there are no separate models for horizontal or vertical installation or for high and low flows.
Rectangular Design
A lot of research and development has gone into the sensor design of the Waterflux 3070. The basis for having a rectangular cross-section goes back to the initial idea of Faraday, the founder of the electromagnetic measuring principle. Based on the design, the magnetic coils are placed closer together to create a strong and stable magnetic field. The distance between the electrodes, however, is relatively larger than the distance between the coils compared to a standard round design.
The patented rectangular design has advantageous results:
- A strong and homogeneous magnetic field
- The closer the coils are together, the better the incoming and outgoing signals.
- Improved signal to noise ratio
- The induced signal voltage is higher than the signal noise level, resulting in accurate measurement over the full measuring range.
- Low energy consumption
- By shortening the distance between the coils, they need less power to be excited. The low energy consumption allows for longer battery life—up to 15 years, depending on the settings of the customer.
- Improved flow profile
- Zero point stability
Due to the constant flow profile, the measurement is stable at no flow and low flows, enabling high accuracies over a wide turndown ratio.
Opportunities Abound
Electromagnetic water meters offer utilities major opportunities to improve revenue and reduce installation and maintenance costs while maintaining initial accuracy and improving long-term accuracy. Based on its innovative design, the 3070 can guarantee a high accuracy over a wide flow range, a low energy consumption and improved flow profile, allowing for very small inlet and outlet sections.
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