New metering technology makes every drop of water count

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New metering technology makes every drop of water count [Copy link]

 

By: Ahmad Bahai, Chief Technology Officer, Texas Instruments

A startling set of statistics shows that in the United States alone, household leaks waste about 900 billion gallons of water each year, which is enough water to supply about 11 million homes each year. Other countries in Europe and Asia face similar problems. Water shortages are expected to make this problem more complicated.

But now there is a solution. Ultrasonic technology enables water meters installed in smart buildings and smart cities to detect and locate leaks, even if they are as small as a drop every few seconds. Cities such as Austin and Antwerp are installing high-tech smart water meters that provide customers with information to find leaks and save water, while also helping to identify infrastructure leaks in aging utility pipes and broken pipes.

“The water available today is the only water we’ll have in the future,” said Holly Holt-Torres, water conservation manager for Dallas Water Utilities. “We have to conserve it. Technology will allow us to do that at higher and higher levels.”

The applications of this ultrasonic technology extend beyond water metering. The technology can also be used to measure natural gas flow and even to detect the composition of gas mixtures flowing through a pipeline. It can even help medical personnel adjust the concentration of oxygen delivered in surgical equipment.

Move with the flow

Ultrasound is not new, of course. Bats, for example, use ultrasonic ranging to avoid obstacles and catch insects at night. In more high-tech applications, ultrasound is used for material identification, automotive collision avoidance, and industrial and medical imaging.

It is now used in water meters and other flow meters. Traditionally, flow meters consisted of an electromechanical system with a rotating spindle or gears that used magnetic elements to generate pulses. However, as with thermostats, motors, and many other everyday devices, electronic systems are rapidly replacing electromechanical systems in flow meters.

“ The water available today is the only water we will have in the future.

We must protect it. Technology will enable us to

to achieve this goal. ”

--Dallas Water Utilities

Holly Holt-Torres, Water Conservation Manager

In these systems, a pair of immersed ultrasonic sensors are used to measure the speed of sound waves in the fluid. The speed at which sound waves travel is a function of the viscosity, velocity and direction of the fluid flowing through the pipe. The stiffness of the medium through which the ultrasound waves travel determines their propagation speed.

The accuracy of the measurement depends on the quality of the sensor, the precision analog circuit design and the signal processing algorithm. Ultrasonic sensors are piezoelectric materials that can convert electrical signals into relatively high-frequency mechanical vibrations of hundreds of kilohertz. Typically, a pair of ultrasonic sensors in the 1-2MHz range must be matched and calibrated to accurately measure flow. They account for a large part of the total cost. The sensor system must operate at extremely low power to ensure a battery life of 15-20 years.

德州仪器先进的流量计量芯片MSP430FR6043，包含独特的模拟前端和算法，可以显著提高精度，同时降低总体成本和功耗。 我们的流量计量架构利用高性能模拟设计、先进算法和嵌入式处理来减少对昂贵的超声波传感器的需求。模拟前端和信号处理算法可补偿传感器不匹配的问题。

Cherish every drop of water

A typical ultrasonic flow meter estimates flow rate by transmitting an ultrasonic wave and measuring the time difference at the receiver. The time difference measurement is usually calculated by a TDC circuit monitoring the time when the received waveform crosses the zero point. The difficulty with this typical measurement method is that it is not sensitive enough to detect flow with high accuracy.

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Our architecture uses a smart analog front end with a high-performance analog-to-digital converter to improve the signal-to-noise ratio and make calibration more precise. This approach has the following five benefits:

1. It can achieve higher accuracy by reducing interference and improving signal-to-noise ratio.

2. This architecture can measure flow rates over a wide dynamic range, from the common flow rates of fire hoses to the flow rates of tiny leaks.

3. 通过使用更低的电压驱动器，可显著节省功耗和成本。每秒一次测量的平均功耗小于3微安。这意味着电池使用寿命可以超过15年。

4. It can detect turbulence, bubbles and other flow anomalies. This is very important for flow analysis and maintenance of pipelines.

5. This technology can overcome the impact of bidirectional flow amplitude changes that may occur in water and gas with higher flow rates.

Many other TI technologies are also critical to high-performance flow meters. Low-power microcontrollers with integrated ultrasonic analog front ends, high-performance clock references, low-quiescent current power management, and ultra-precise impedance matching of transmit driver and receive amplifier paths are examples of differentiating technologies in flow meters.

Together, these technologies help protect one of our most precious resources.