RFID Helps to Locate Underground Infrastructure
3M Company has claimed to have developed an effective way to locate the path of underground plastic pipes and conduits, eliminating the need for tracer wire and test stations and the problems and costs associated with them.
Traditionally a number of techniques have been used, including tracer wires, but these have limitations. They require power to be effective and cease to operate if broken.
The company said that its new Electronic Marking System (EMS) Caution Tape “uses a new EMS marker technology embedded into a caution tape for installation near or above the buried facility and helps provide continuous path location.” Technology embedded in the tape transmits a signal to a special reader enabling the precise location and route of the pipe or cable to be found.
3M says the markers require no batteries and there is no need to hook up an external transmitter or search for access points. The markers work independently so that if a section of caution tape is cut or removed, the other markers on the tape will continue to provide accurate location.
The tape comes in different versions for different types of infrastructure (water, wastewater, gas, telco). Each uses a different frequency to help reduce the risk of accidentally locating and excavating the wrong buried facilities. 3M says the tape can last for up to 50 years.
In fact, the tape uses RFID technology, which is finding application in a broad swath of industries. If you’ve ever bought a DVD or a book and seen on the back a label with lots of wire squares one inside the other, that’s one type of RFID tag.
Those wires are an antenna. The bit you don’t see is a microchip and that’s the heart of the device. A reader placed near the tag creates an electromagnetic field that induces a current in the antenna. This current energizes the microchip, which then uses the same antenna to transmit data stored within it. The reader collects and interprets the data.
RFID technology works only over short ranges. As the distance increase the power that the tag is able to extract from the reader decreases, reducing the power of its transmission, which in turn has to traverse a greater distance to the reader. 3M’s EMS tape is only good for a maximum of 600mm from the surface.
Active RFID technology is also available, but this requires an external power source, which would neutralize one of the key advantages of 3M’s tape.