CS505 Fuel Moisture Sensor Revision: 5/08 C o p y r i g h t © 1 9 9 8 - 2 0 0 8 C a m p b e l l S c i e n t i f i c , I n c .
Warranty and Assistance The CS505 FUEL MOISTURE SENSOR is warranted by CAMPBELL SCIENTIFIC, INC. to be free from defects in materials and workmanship under normal use and service for twelve (12) months from date of shipment unless specified otherwise. Batteries have no warranty. CAMPBELL SCIENTIFIC, INC.'s obligation under this warranty is limited to repairing or replacing (at CAMPBELL SCIENTIFIC, INC.'s option) defective products.
CS505 Table of Contents PDF viewers note: These page numbers refer to the printed version of this document. Use the Adobe Acrobat® bookmarks tab for links to specific sections. 1. General Description.....................................................1 2. Specifications ..............................................................1 3. Installation....................................................................2 4. Wiring............................................................................4 5.
CS505 Fuel Moisture Sensor 1. General Description The CS505 Fuel Moisture Sensor provides an automated measurement of the moisture content of a standard 10-hour fuel moisture dowel. The moisture content of the 10-hour fuel sensor represents the moisture content of smalldiameter (10-hour time lag) forest fuels. Traditionally, the standard fuel moisture stick consists of a rack of four 1/2 inch diameter ponderosa pine dowels. The resulting rack is about 20 inches long with an oven-dry weight of 100 grams.
CS505 Fuel Moisture Sensor the media surrounding the stainless steel strips. The dielectric constant is predominantly dependent on the water content of the wood. Digital circuitry scales the oscillation frequency to an appropriate range for measurement with a datalogger. The CS505 output is essentially a square wave with an amplitude of ±2.5 VDC. The frequency of the square wave output ranges from approximately 600 to 1500 Hz.
CS505 Fuel Moisture Sensor The mounting stake ships with a package of 12 ultraviolet light resistant cable ties. The mounting stake has five holes punched along the edge of the shaft. There are two pairs of holes higher and one single hole lower on the shaft. When the stake is inserted into the ground to a depth level with the lower hole, the probes are at 12 inches or about 30 centimeters above the ground surface.
CS505 Fuel Moisture Sensor 4. Wiring Connections to Campbell Scientific dataloggers are given in Table 4-1. When Short Cut for Windows software is used to create the datalogger program, the sensor should be wired to the channels shown on the wiring diagram created by Short Cut. TABLE 4-1.
CS505 Fuel Moisture Sensor 5.1 CR10X Programming A program to measure a CS505 fuel moisture sensor using the Period Averaging instruction P27. P27 is the preferred measurement technique with a Campbell Scientific, Inc. datalogger. P27 is not an option in the 21X or CR7 datalogger. ;{CR10X} ;CR10X Program for CS505 *Table 1 Program 01: 10.
CS505 Fuel Moisture Sensor 5.2 21X Programming A program to measure a CS505 fuel moisture sensor using the Pulse Count Instruction P3. The fuel moisture sensor is measured when flag 1 is set high. The measurement is made then flag 1 is set low. ;{21X} ;21X Program for CS505 *Table 1 Program 01: 10.
CS505 Fuel Moisture Sensor 9: Polynomial (P55) 1: 1 Reps 2: 3 X Loc [ FuelM ] 3: 3 F(X) Loc [ FuelM ] 4: -220.14 C0 5: 365.89 C1 6: -114.96 C2 7: 0 C3 8: 0 C4 9: 0 C5 10: Do (P86) 1: 51 Set Port 1 Low 11: End (P95) 5.
CS505 Fuel Moisture Sensor 6. Maintenance The sensor element should be changed at least once a year with a new element in the spring. Since the characteristics of wood change so rapidly, more frequent replacements may be desirable. To change the sensor element, loosen the Phillips head screws and replace with the new element. Tighten the screws after replacing the element.
Appendix A. Explanation of Experimental Data EXPERIMENTAL DATA ERROR DISTRIBUTION 6 RMS ERROR 2.37% Error % WATER CONTENT (by weight) 5 RMS ERROR 2.21% 4 RMS ERROR 1.43% RMS ERROR 0.98% 3 2 1 0 -1 -2 -3 -4 -5 % WATER CONTENT (by weight) -6 0 10 20 30 40 50 FIGURE A-1. Experimental Data Error-Distribution Experiments were conducted to characterize measurement error and to determine the calibration polynomial coefficients used to convert the output signal to percent moisture content.
Appendix A. Explanation of Experimental Data The full scale range is broken into four sub ranges: 0-10, 10-20, 20-30, and 30-50 percent. The computed rms errors are shown in Table 1. For each range band an error band was determined in which more than 90 percent of all measurements fall (also shown in Table A-1 and Figure A-1). TABLE A-1. Accuracies at Measurement Ranges Range 90% of All Measurements rms Error 0 to 10% ±2% ±1% 10 to 20% ±3% ±1.5% 20 to 30% ±5% ±2.
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