CS505 Fuel Moisture Sensor
Revision: 5/08
Copyright © 1998-2008
Campbell Scientific, Inc.
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.
The customer shall assume all costs of removing, reinstalling, and shipping
defective products to CAMPBELL SCIENTIFIC, INC. CAMPBELL
SCIENTIFIC, INC. will return such products by surface carrier prepaid. This
warranty shall not apply to any CAMPBELL SCIENTIFIC, INC. products
which have been subjected to modification, misuse, neglect, accidents of
nature, or shipping damage. This warranty is in lieu of all other warranties,
expressed or implied, including warranties of merchantability or fitness for a
particular purpose. CAMPBELL SCIENTIFIC, INC. is not liable for special,
indirect, incidental, or consequential damages.
Products may not be returned without prior authorization. The following
contact information is for US and International customers residing in countries
served by Campbell Scientific, Inc. directly. Affiliate companies handle
repairs for customers within their territories. Please visit
www.campbellsci.com to determine which Campbell Scientific company
serves your country. To obtain a Returned Materials Authorization (RMA),
contact CAMPBELL SCIENTIFIC, INC., phone (435) 753-2342. After an
applications engineer determines the nature of the problem, an RMA number
will be issued. Please write this number clearly on the outside of the shipping
container. CAMPBELL SCIENTIFIC's shipping address is:
CAMPBELL SCIENTIFIC, INC.
RMA#_____
815 West 1800 North
Logan, Utah 84321-1784
CAMPBELL SCIENTIFIC, INC. does not accept collect calls.
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. Datalogger Programming............................................4
5.1 CR10X Programming...............................................................................5
5.2 21X Programming ....................................................................................6
5.3 CR1000 Programming..............................................................................7
6. Maintenance.................................................................8
Appendix
A. Explanation of Experimental Data.........................A-1
Figures
3-1. Exploded View of CS505 and CS206 Mounting ....................................3
3-2. CS505 Installation Over Forest Floor, 30cm Over Duff Layer...............3
A-1. Experimental Data Error-Distribution............................................... A-1
Tables
4-1. Wiring for CS505.................................................................................... 4
A-1. Accuracies at Measurement Ranges.................................................. A-2
i
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. The characteristic time constant
of the rack is 10 hours. The rack is mounted 12 inches or about 30 centimeters
above the forest floor. The rack is left outside continually exposed to the same
conditions as forest fuels. The rack absorbs and desorbs moisture from its
surroundings. As the rack transfers moisture, its weight changes. Periodic
weighing of the rack determines changes in moisture content and provides an
indication of moisture changes in forest fuels.
The CS505 sensor incorporates the same carefully selected USFS standard
ponderosa dowels as the traditional weighing fuel moisture racks. No artificial
materials (e.g., epoxy sealant) are added to the dowel that would adversely
influence the natural behavior characteristics of the dowel. Because the
complete dowel surface is accessible for moisture exchange, the response of
the CS505 is similar to that of the traditional weighing racks. To optimize
probe-to-probe repeatability and to allow probe interchangeability without
individual calibration, two additional sorts are performed on the dowels before
they are selected to be used as a sensor. First, the dowels are sorted dry by
density to improve accuracy in the dry range of 0 to 15%. Second, the dowels
are sorted after a 50-minute soak by weight to reduce probe-to-probe time
response variation and minimize variability in the wet range of 20 to 50%.
Even after careful selection and sorting is performed to choose the most
representative dowels, the majority of measurement error is due to the
variability of wood. Wood’s ability to transfer moisture is dependent on many
variables, primarily cell structure and wood resin content. These variables
change over time and after repeated wetting and drying cycles. Only a small
amount of overall measurement error is due to the electronic circuitry.
2. Specifications
The fuel moisture sensor consists of two stainless steel strips pressed into
groves in a standard 1/2 inch ponderosa pine dowel and secured with nylon tie
wraps. The probe connects to the electronics with two Phillips head screws.
A shielded four-conductor cable is connected to the circuit board to supply
power, enable the electronics, and monitor the signal output. The printed
circuit board is encapsulated in a waterproof epoxy housing.
High speed electronic components on the circuit board are configured to
oscillate when power is applied. The output of the circuit is connected to the
fuel moisture probe which acts as a wave guide. The oscillation frequency and
therefore output signal of the circuit is dependent on the dielectric constant of
1
Loading...