Pressure sensor: Wireless self-contained pressure transmitter family
New wireless instrumentation devices are becoming more common, and IntelliSensing LLC has introduced an interesting family of pressure sensors using ZigBee (IEEE 802.15.4) communication. This capability is coupled with strain gage sensors covering a wide range of pressures from 0-100 psi all the way to 0-10,000 psi. The sensors themselves are sophisticated, including internal barometric transducers to provide precise compensation for true gage and absolute readings.
Measuring 38 mm wide and 166 mm long when mounted, the PS1 provides a completely self-contained wireless pressure instrument using the latest ZigBee technology. Each unit transmits its reading to a suitable base station, which can then pass it to a host system or DCS. The current offering does not support self-forming mesh networks, but the company anticipates adding that technology. One base station can theoretically talk to as many as 65,000 devices, although latency issues would make that difficult. As a practical matter, the number of gateways will be influenced more by reporting interval and deterministic needs, along with transmitting distance.
The company says there are two transmitting modes depending on the distance to the base unit. The standard range is good for 30 m in a congested indoor environment or 100 m in a clear outdoor line-of-sight installation. Using a default reporting interval of 10 s, this supports battery life of 1 year. If longer distances are involved, the power can be increased to cover 100 m and 1500 m respectively, but this shortens battery life to 2 months. The user can extend battery life by selecting a longer reporting interval or changing to a report by exception mode.
There is only one choice of inlet thread. The configuration is a male 7/16-20, 37° flare fitting with adapters available to change it to a conventional
—Edited by Peter Welander, process industries editor, PWelander@cfemedia.com ,
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