Automated fuel moisture can be made using Campbell Scientific's CS505 Fuel Moisture sensor. The CS505 measures the moisture content of a ponderosa pine dowel that is fabricated to USFS specifications. The dowels have the same 1/2" diameter, 20" long dimensions as those used on the traditional weighing fuel moisture racks. The dowels have undergone two additional sorts to optimize probe-to-probe repeatability and to allow probe interchangeability without individual calibration.
The CS505 Fuel Moisture Sensor produces a ±2.5 volt square wave. The frequency of the square wave is read with an analog or pulse channel of a CSI datalogger and is converted to percent fuel moisture using a quadratic calibration. The response is similar to the traditional weighing racks because the entire dowel surface is exposed for moisture exchange.
Features
Measures moisture content of USFS-specified, 10-hour, Ponderosa pine dowel
Dowel dimensions are the same as those used in fuel moisture racks
Dowel is easily replaced in the field
Specifications
Operating range: 0 to 70% moisture content
Power supply: 9 to 18 Vdc
Accuracy ±1% rms @ 0 to 10% moisture content; ±2.4% rms @ 30 to 40%
Current use: 70 mA active/10 µA quiescent
Output signal: ±2.5 Vdc square wave with an output frequency of 600 to 1500 Hz
