Decagon Devices GS1 User manual

Operator’s Manual
Decagon Devices, Inc.
Version: August 5, 2014 — 08:49:46

GS1
Decagon Devices, Inc.
2365 NE Hopkins Court
Pullman WA 99163
Phone: [phone]
Fax: [phone]
Website: www.decagon.com
Email: supp[email protected] or [email protected]
Trademarks
“ECH2O” is a registered trademark of Decagon Devices, Inc.
c
2001-2014 Decagon Devices, Inc.
All Rights Reserved
ii

GS1 CONTENTS
Contents
1 Introduction 1
1.1 Warranty ......................... 1
1.2 Seller’s Liability . . . . . . . . . . . . . . . . . . . . . . 2
2 About GS1 3
2.1 Background........................ 3
2.2 Specifications ....................... 3
3 Theory 5
3.1 Volumetric Water Content . . . . . . . . . . . . . . . . 5
3.2 Procedure......................... 5
3.3 Orientation ........................ 6
3.4 Removing the Sensor . . . . . . . . . . . . . . . . . . . 6
4 Connecting Sensors 7
4.1 Wiring........................... 8
5 Collecting Data 10
5.1 Sample Program . . . . . . . . . . . . . . . . . . . . . 10
6 Calibration 13
6.1 Sensor Calibration Values . . . . . . . . . . . . . . . . 13
7 Maintenance and Troubleshooting 16
8 Declaration of Conformity 18
iii

GS1 1 INTRODUCTION
1 Introduction
Thank you for choosing Decagon’s GS1 Volumetric Water Content
sensor. This manual can help you understand the sensor features and
ensure successful sensor operation. We hope you find the contents of
this manual useful in understanding your instrument and maximiz-
ing its benefit to you.
There are several ways to contact Decagon if you ever need assis-
tance with your product, have any questions, or feedback. Decagon
has Customer Service Representatives available to speak with you
Monday through Friday, between 8am and 5pm Pacific time.
Note: If you purchased your sensor through a distributor, please con-
tact them for assistance.
Email:
supp[email protected] or [email protected]
Phone:
509-332-5600
Fax:
509-332-5158
If contacting us by email or fax, please include as part of your mes-
sage your instrument serial number, your name, address, phone, fax
number, and a description of your problem or question.
Please read these instructions before operating your sensor to en-
sure that it performs to its full potential.
1.1 Warranty
The sensor has a 30-day satisfaction guarantee and a one-year war-
ranty on parts and labor. Your warranty automatically validates
upon receipt of the instrument.
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1 INTRODUCTION GS1
1.2 Seller’s Liability
Seller warrants new equipment of its own manufacture against de-
fective workmanship and materials for a period of one year from the
date of receipt of equipment.
Note: We do not consider the results of ordinary wear and tear,
neglect, misuse, accident as defects.
The Seller’s liability for defective parts shall in no event exceed the
furnishing of replacement parts “freight on board” the factory where
originally manufactured. Material and equipment covered hereby
which is not manufactured by Seller shall be covered only by the
warranty of its manufacturer. Seller shall not be liable to Buyer for
loss, damage or injuries to persons (including death), or to property
or things of whatsoever kind (including, but not without limitation,
loss of anticipated profits), occasioned by or arising out of the instal-
lation, operation, use, misuse, nonuse, repair, or replacement of said
material and equipment, or out of the use of any method or process
for which the same may be employed. The use of this equipment con-
stitutes Buyer’s acceptance of the terms set forth in this warranty.
There are no understandings, representations, or warranties of any
kind, express, implied, statutory or otherwise (including, but with-
out limitation, the implied warranties of merchantability and fitness
for a particular purpose), not expressly set forth herein.
2

GS1 2 ABOUT GS1
2 About GS1
The GS1 determines volumetric water content (VWC) by measuring
the dieletric constant of the medium using capacitance and frequency
domain technology. The 70 MHz frequency minimizes salinity and
textural effects, making the GS1 accurate in almost any soil or soil-
less medium. It arrives with generic calibrations for mineral soils and
soilless media included in this Operator’s Manual.
The two-prong design and high measurement frequency allows the
GS1 to measure VWC from 0 to 100% (VWC of saturated soils is
generally 40 to 60% depending on the soil type) and allows accurate
measurement of all soils and soilless medias with a wide range of
salinities.
2.1 Background
In 2012, Decagon released our first stainless steel needle sensor, the
GS3. The GS3 measures volumetric water content, temperature,
and electrical conductivity. The sensor has a side-entry cable, which
made it extremely easy to install in a trench application.
At the time, the GS3 was Decagon’s highest priced water content
sensor. However, its rugged design made it one of our most popular
sensors. Our goal in developing the GS1 is to provide customers with
a low-cost sensor that has the durability of the GS3.
2.2 Specifications
Measurement Time: 10 ms (milliseconds)
Accuracy: ±0.03 m3/m3in typical soils, up to 8 dS/m saturation
extract EC.
With soil-specific calibration: ±0.01 to 0.02 m3/m3in any ma-
terial.
Resolution: 0.001 m3/m3VWC in mineral soils
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2 ABOUT GS1 GS1
Power Requirements: 3.0 VDC to 15 VDC (absolute maximum) @
15 mA
Output: 1,000 to 2,500 mV
Operating Environment: -40 to 50 ◦C1
Range of Measurement: 0 to 100% VWC
Sensor dimensions: 8.9 cm x 1.8 cm x 0.7 cm
Connector Types: 3.5 mm (stereo) plug or stripped & tinned lead
wires (Pigtail)
Cable Length: 5 m standard; custom cable length available upon
request
Data logger Compatibility (not exclusive):
•Decagon: Em50, Em50R, Em50G, Em5b, and ProCheck
•Campbell Scientific: CR10X, CR850, 1000, 3000, etc.
1Sensors can be used at higher temperatures under certain conditions. Please
contact Decagon for assistance.
4

GS1 3 THEORY
3 Theory
3.1 Volumetric Water Content
The GS1 sensor uses an electromagnetic field to measure the dielec-
tric permittivity of the surrounding medium. The sensor supplies a
70 MHz oscillating wave to the sensor prongs that charges according
to the dielectric of the material. The stored charge is proportional
to substrate dielectric and substrate volumetric water content. The
GS1 measures the charge and outputs a raw value that strongly cor-
relates to VWC. Decagon has a few helpful reminders to consider
before using your sensor.
•If you are installing sensors in a lightning prone area with
a grounded data logger, please see our Application Note at
www.decagon.com/lightning.
•Decagon advises that you test the sensors with your data log-
ging device and software before going to the field.
Before you select a site for installation, remember that the soil next
to the sensor surface has the strongest influence on its readings. It
is important to avoid air gaps or extremely compact soil around the
sensor, which can skew readings. Do not install the GS1 next to
large metal objects, which can attenuate the sensor electromagnetic
field and distort output readings.
Because the sensors have gaps between their prongs, it is also impor-
tant to consider the size of the media where you insert the sensor. It
is possible to get sticks, bark, roots or other material stuck between
the sensor prongs, which will adversely affect readings. Finally, be
careful when inserting the sensors into dense soil, as the prongs can
bend if you apply excessive force when pushing them into the soil.
3.2 Procedure
Excavate a hole or trench a few centimeters deeper than the sensor
installation depth. At the installation depth, shave off some soil from
the vertical soil face to expos undisturbed soil. Insert the sensor into
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3 THEORY GS1
the undisturbed soil face until both needles are pushed completely
in the soil face so that the cable is coming towards the soil surface
with no bends. The tip of each prong has been sharpened to make
it easier to push in the sensor. Be careful to avoid the sharp tips.
Back fill the trench taking care to pack the soil back to natural bulk
density around the white PVC portion of the sensor.
3.3 Orientation
You may orient the GS1 in any direction. However, to eliminate cable
strain, orient the sensor vertically so that the cable exit is closest to
the soil surface, and does not need to bend.
3.4 Removing the Sensor
When removing the sensor from the soil, do not pull it out of the
soil by the cable! Doing so may break the internal connections and
make the sensor unusable. Instead, dig down to where the sensor is
located and uninstall horizontally.
6

GS1 4 CONNECTING SENSORS
4 Connecting Sensors
Decagon designed the GS1 sensor for use with our Em50 series data
loggers, the Em5b, or the ProCheck handheld reader. The standard
sensor (with a 3.5 mm “stereo plug” connector) quickly connects to
and is easily configured within a Decagon logger or ProCheck. (Fig-
ure 1)
Figure 1: Stereo Connector
The GS1 sensor incorporates several features that also make it an
excellent sensor for use with third party loggers. Customers may
purchase the sensor with stripped and tinned wires (pigtail) for ter-
minal connections.
The GS1 sensor comes standard with a five meter cable. Customers
may purchase sensors with custom cable lengths for an additional fee
(on a per-foot fee basis). Obtaining custom length cables eliminates
the need for splicing the cable (a possible failure point).
Connecting to an Em50/Em50R Logger
Decagon designed the GS1 to work specifically with the Em50 and
Em5b data loggers. Simply plug the 3.5 mm stereo plug connector
directly into one of the five sensor ports. Next, configure the logger
port for the GS1 and set the measurement interval.
Connecting to ECH2O Utility
Configure your Decagon data loggers using either ECH2O Utility
7