Remote control

With the soaring cost and scarcity of resources, accurate metering is becoming increasingly important for both utility companies and householders to monitor usage and plan for demand.

UK technology consultant Sagentia has developed a system based on mathematical principles that allows a common type of water meter to be read remotely for the first time.

Automatic Meter Reading (AMR) technology is an essential part of utility companies’ armoury, automatically gathering data from metering systems and transmitting it to a central database.

As water meters need to remain in the ground for a number of decades, by law in some parts of the world there must be a mechanical means of logging the amount of water used, as batteries could go flat or electric systems could fail.

This is usually done in a register, the top part of the water meter, with a combination of odometer-style wheels and a dial. Encoding is a way of electronically reading the mechanical position of the wheels, which allows AMR to be carried out.

The reading can be collected using a handheld data logger, a low-powered radio transmitter in the meter picked up by a reading van, or the meter can be connected via a modem to the telephone line, which also powers it.

There are two principles of domestic water metering throughout the world. One is positive displacement metering, which works like a piston in a car, measuring out a fixed quantity of water every time it goes round. With these meters, there is a lot of energy available from the water to drive the register round, with enough left for a system to detect the physical location of the wheels.

The other, multi-jet meters, work like a turbine, with an impeller that sits in the flow of water. As it is resistant to blockage, it is used extensively in regions of the world prone to particulates. Available energy is limited, and any small amount of friction on the register that might be caused by a detection system could cause it to under-read significantly.

Cambridge company Sagentiaworked with client Master Meter to develop AccuLinx, a contact-free water meter register that can be used with multi-jet meters without affecting the reading. Master Meter is a US company owned by an Israeli corporation, with markets in the US, Canada, Europe and South America.

Robin Lee, head of science and technology at Sagentia, said: ‘At the very beginning of AMR in this industry, they used to put little gold fingers and switches on all the wheels that went round and they could use a system of switches to encode the wheel positions. You can’t do that with multi-jet meters as the tiny bits of friction you get from the wipers and the switches is way too much.

‘There has been a need in the industry to have an encoding register which is very low friction, which in general has meant for AMR you mustn’t touch the wheels — you need to have a non-contact encoding technology that doesn’t introduce any friction.’

Sagentia’s solution, which lies behind AccuLinx, is dubbed Gray Wheels, a robust and power-efficient way of encoding the position of the odometer wheels without touching them. The power used comes from the meter reading technology.

‘At the time of reading, the meter reader comes along with a data logger. When they power it up to read the meter, the register steals a small amount from their data logger. It powers up for a second, reads the position of all the wheels then turns off again,’ said Lee. ‘The electronics only gets turned on for that moment every month, or whenever they read the meter.’