Water sensor

A new, inexpensive sensor currently being tested in Pisa, Italy, has been designed to locate water leaks from utility company pipes.

The sensor, developed on behalf of Pisa’s water supply company Acque by researchers at the Fraunhofer Institute for Silicon Technology and their Italian colleagues at Sensordynamics, are silicon based and cost around five percent of the average price of their high-end counterparts.

The new probes function according to the same principle as mass air flow sensors, which have been used for some time to measure the air intake in car engines.

At the heart of the sensor are two heating wires, which are mounted one behind the other on a thin membrane. An electric current flowing through the wires heats them to a constant temperature. When cold water flows past them, the front wire gives off more heat into the water than the rear one, which is in its slipstream.  Accordingly, a higher current has to flow through the front wire in order to keep the temperature constant. On the basis of this difference in electrical current, it is possible to determine the speed and volume of the water traveling through the pipes.