Ultrasonic meter makes every drop count

Drip.  Drip.  Drip.

Drip. Drip. Drip.With leaks as slow as one drop a second flowing down the drain – along with the streams of revenue that they might have generated − utility companies around the world have been searching for ways to measure water use with more accuracy
and precision.

Their search is over.

A new single, integrated chip – the MSP430FR6047 microcontroller (MCU)  ̶  will give utility companies the ability to measure the flow of water – as well as heat and natural gas − with unprecedented precision and accuracy. The device uses soundwaves to calculate how much volume is flowing through pipes.

The technology promises to upend the current market for meters that utility companies use to measure – and bill – for the services they provide and to deliver exceptional performance in industrial applications.

“Our teams understood the market needs at a very deep level,” said Shailesh Thakurdesai, MSP430 MCU product marketing engineer. “We were all focused on solving a customer problem in a very specific way.”

Down the drain

In many countries, water meters currently are built around a mechanical paddle wheel in the pipe that turns as water is delivered to homes and businesses. Water flowing through the meter creates a pulse, and a microcontroller – in many cases supplied by our company – then measures how much water you use. Local utility companies send bills to their customers each month based on usage.

That system works fine for short periods, but over time the metal in the pipe corrodes and the moving parts deteriorate. The paddle wheels can’t measure the flow accurately. Temperature changes affect the accuracy of the measurements. Slow drips and small leaks can’t be detected.

The numbers add up fast. In the United States, an average household with dripping faucets and leaking toilets can waste more than 10,000 gallons of water annually. Nationwide, leaks waste more than 1 trillion gallons a year, according to the Environmental Protection Agency.

For utility companies, that’s water and money down the drain.

Analog-to-digital technology

Flow meters in the United States are common. But in some countries – India, for example – there are few. Instead of having a meter that measures how much water customers use each month, many people who live there pay a flat fee and use as much water as they want to.

A few years ago, when Anand Dabak heard that Mumbai wanted to explore using meters to measure water usage, his interest peaked. Anand – a researcher in Kilby Labs, our applied research center – is a TI Fellow with a deep background in signal processing.

“We thought we could create a unique high-speed analog-to-digital-based technique that would differentiate our technology to measure the water flow rates much more accurately and help develop water meters that would be cost-effective and practically feasible for individual apartments within a building,” Anand said.

Single-chip system

The low-power, single-chip system that emerged from our technology-development process – MSP430FR6047 MCU  ̶  relies on ultrasonic waves to measure how much water is moving through pipes. Two transducers send sound waves through the pipe and, based on the size of the pipe and how long it takes for the signals to reach their receivers, the flow rate can be measured at a rate as low as one drop per second.

In addition to being accurate and precise, the technology uses little power.

“When you’re building a house and installing the water meter, you don’t want to look at it again for at least 20 years, so the battery life is of utmost importance,” Shailesh said.

A software library, an easy-to-use software interface via our new Ultrasonic Design Center, and a hardware evaluation board, EVM430-FR6047, help customers get their smart meters to market in months rather than the years they required with other technologies.

Unique approach

Ultrasonic meters are not new. Millions – measuring the use of water, natural gas and heat  ̶  have been installed since they were introduced in about 2009. But these meters have limitations in measurements at lower flow rates and they use multiple chips on a circuit board.

“Many existing meters aren’t able to measure the small leakages, and utility companies are losing revenue as a result,” Shailesh said. “But there is also new construction. New houses are being built. There are new requirements. There is always demand for new meters.”

Our team developed a unique approach that included new methods to extract more accurate information about water flow, deliver accuracy to one-trillionth of a second, achieve stable measurements during wide temperature swings, and perform higher levels of computing at lower current.

“We clearly understood our market and what our customers said were their top challenges,” Shailesh said. “We clearly understood the problems with the existing technology and how we could solve them in a unique way.”