Decagon Devices 5TE Operator's Manual

Water content, ec and temperature sensors
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5TE
Water Content, EC
and Temperature Sensors
Operator's Manual
Version 2

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Summary of Contents for Decagon Devices 5TE

  • Page 1 Water Content, EC and Temperature Sensors Operator’s Manual Version 2...
  • Page 2 ©2008 Decagon Devices, Inc. All rights reserved. Decagon Devices, Inc. 2365 NE Hopkins Court Pullman W A 99163 www.decagon.com...
  • Page 3: Table Of Contents

    Seller’s Liability ......3 2. About the 5TE ....4 Background Info .
  • Page 4 5TE Operator’s Manual Table of Contents Dielectric Permittivity ..... . . 17 Electrical Conductivity ..... . 17 Temperature .
  • Page 5: Introduction

    5TE Operator’s Manual 1. Introduction 1. Introduction Thank you for choosing Decagon’s 5TE for measuring water content, temperature, and EC. This manual is designed to help you understand the probe’s features and how to use this device successfully. Specifications Volumetric water content: Range: Apparent dielectric permittivity (ε...
  • Page 6: Contact Information

    5TE Operator’s Manual 1. Introduction Temperature Range: -40-50 °C Resolution: 0.1 °C Accuracy: ±1 °C General Dimensions: 10 cm (1) x 3.2 cm (w) x 0.7 cm (d) Prong Length: 5.2 cm Dielectric Measurement Frequency: 70 MHz Measurement Time: 150 ms (milliseconds) Power requirements: 3.6 - 15 VDC, 0.3 mA quiescent, 10...
  • Page 7: Warranty Information

    5TE Operator’s Manual 1. Introduction Warranty Information All Decagon products have a 30-day satisfaction guarantee and a one-year warranty. Seller’s Liability Seller warrants new equipment of its own manufacture against defective workmanship and materials for a period of one year...
  • Page 8: About The 5Te

    O-TE, but the location of the EC measurement is in the stainless steel screws instead of gold traces. The use of stainless steel screws has made the 5TE a more robust sensor. Additionally, the 5TE utilizes a 5 point dielectric calibration to...
  • Page 9 5TE Operator’s Manual 2. About the 5TE Figure 1: 5TE Components...
  • Page 10: Theory

    3. Theory 3. Theory Volumetric Water Content The 5TE probe uses an electromagnetic field to measure the dielectric permittivity of the surrounding medium. The probe supplies a 70 MHz oscillating wave to the probe prongs that charges according to the dielectric of the material. The stored charge is proportional to soil dielectric and soil volumetric water content.
  • Page 11: Electrical Conductivity

    (the ratio of the distance between the electrodes to their area). The 5TE uses a 2-probe array to measure the EC. The array is located on the screws of two of the 5TE prongs. Small amounts of oil from skin contact with the screws will cause significant inaccuracy in the EC measurement.
  • Page 12: Converting Bulk Ec To Pore Ec

    σ directly. As one would expect, this is a time consuming and labor intensive process. The 5TE measures the electrical conductivity of the bulk soil surrounding the probes (σ ). A considerable amount of research has been conducted to determine the relationship between σ...
  • Page 13: Pore Water Vs. Solution Ec

    - 20) soil where T is the soil temperature (C) measured by the 5TE. soil ε is also measured by the 5TE. Raw VWC counts can be con- verted to bulk dielectric by the ECH O-TE dielectric calibra- tion: ε ε...
  • Page 14 5TE Operator’s Manual 3. Theory sured dielectric permittivity of the medium. However, pore water EC is not the same as solution EC. Pore water EC is the electrical conductivity of the water in the pore space of the soil. One could measure this directly if the soil was squeezed under high pressure to force water out of the soil matrix and that water was collected and tested for EC.
  • Page 15: Calibration

    Dielectric Permittivity Each 5TE sensor has been calibrated to measure dielectric permittivity ( ε ) accurately in the range of 1 (air) to 80 (water). The unprocessed raw values reported by the 5TE have units of ε *50. Mineral Soil Calibration...
  • Page 16: Calibration In Non-Soil Media

    5TE sensor which will improve the accuracy to 1-2% for any soil. For more information on how to per- form your own soil-specific calibration, or to have Decagon’s...
  • Page 17: Connecting Sensors

    5TE. To update your software to the latest versions, please visit Decagon’s software download site: http://www.deca- gon.com/home/downloads.php To use the 5TE with your Em50 data logger, simply plug the stereo plug into one of the five ports on the data logger and use either ECH...
  • Page 18: Mm Stereo Plug Wiring

    5TE Operator’s Manual 5. Connecting Sensors Mobile, or DataTrac software (see respective manuals) to con- figure that port for the 5TE and set the measurement interval. 3.5mm Stereo Plug Wiring 5TE sensors used with Decagon loggers come with a 3.5mm “stereo plug”...
  • Page 19: Connecting To A Non-Decagon Data Logger

    Ground (Bare) Sensor cable Excitation (White) 5TE sensors with stripped and tinned cable option can be made with custom cable lengths (up to 250ft) on a per-foot fee basis. This option gets around the need for splicing wire (a possible failure point).
  • Page 20: Logger Communications

    5. Connecting Sensors NOTE: The acceptable range of excitation voltages is from 3-15 VDC. If you wish to read the 5TE with the Campbell Scientific Data Loggers, you will need to power the sensors off of the switched 12V port.
  • Page 21: Dielectric Permittivity

    Electrical Conductivity The raw electrical conductivity value ( σ ), is valid in the range 0 to 1022. The 5TE uses a compression algorithm to extend the range of electrical conductivity that can be repre- sented by a 10-bit value. σ...
  • Page 22: Temperature

    The raw temperature value, (T ), is valid in the range 0 to 1022. The 5TE uses a compression algorithm to extend the range of temperatures that can be represented by a 10-bit value. The sensor sends temperature with 1/10 of a degree Celsius resolution for the range -40 to 50.0°C.
  • Page 23: Installing The Probes

    5TE Operator’s Manual 6. Installing the Probes 6. Installing the Probes NOTE 1: Make sure the screw electrodes on the 5TE are clean before installing the sensors. See the sensor cleaning section at the end of the manual. NOTE 2: Decagon advises that you test the sensors with your data log- ging device and software before going to the field.
  • Page 24 Insert the sensor into the undisturbed soil face until the entire sensing portion of the 5TE is inserted. The tip of each prong has been sharpened to make it easier to...
  • Page 25: Orientation

    Removing the Probes When removing the 5TE probe, do not pull it by the cable! This could break the internal wires and cause the probe to malfunction or not function at all.
  • Page 26: Multiple Probe Installation

    The distance between the screws is an important part of the EC calculation. If 5TE sensors are placed close together (within 20cm), it is possible for some of the current that leaves the excited screw to pass through the nearby sen- sor’s ground screw, thus producing an erroneous sensor read-...
  • Page 27: Campbell Scientific Programs

    Campbell Scientific datalogger. The following application notes containing Campbell Scientific sample programs are available for the 5TE: • Using the 5TE with Campbell Scientific CR10X Data logger • Using the 5TE with Campbell Scientific CR1000 •...
  • Page 28: Troubleshooting&Sensor Care

    5TE Operator’s Manual 8. Troubleshooting&Sensor Care 8. Troubleshooting&Sensor Care If you encounter problems with the 5TE sensor, they most likely will manifest themselves in the form of incorrect or erroneous readings. Before contacting Decagon about the sensor, do the following: Datalogger 1.
  • Page 29: Sensor Cleaning

    5TE Operator’s Manual 8. Troubleshooting&Sensor Care Sensor Cleaning The EC measurement is very sensitive to the presence of non- conducting contamination on the screws, especially at high EC. The most common source of contamination is skin oil from handling the screws traces with bare hands. Figure 3a...
  • Page 30: Cleaning Method

    5TE Operator’s Manual 8. Troubleshooting&Sensor Care Cleaning Method 1. Wash the screws thoroughly with a drop of Dawn or other grease cutting dish soap and warm water. Be sure that the soap doesn’t contain skin conditioners or moisturizers. 2. Rinse the probe and screws thoroughly with tap water to remove all remnants of soap.
  • Page 31: Declaration Of Conformity

    This is to certify that the ECH O-TE, ECH O EC-TM and 5TE dielectric soil moisture probes, manufactured by Deca- gon Devices, Inc., a corporation based in Pullman, Washing- ton, USA meet or exceed the standards for CE compliance as per the Council Directives noted above.
  • Page 32 Cleaning probe 26 screws 26 Contact Information 2 Converting bulk EC to pore EC 8 CSI loggers using 5TE probes with 23 Declaration of Conformity 27 Dielectric Permittivity 11, 17 ECH2O Utility 1.10 13 Electrical Conductivity 7 Extension Cables 14...
  • Page 33 5TE Operator’s Manual Index temperature 6 volumetric water content 6 Installation orientation 21 removing the probe 21 Logger Communication 16 Mineral Soil Calibration 11 Pore Water EC 8 Power Requirements 2 Raw Values 17 Screws 7 Seller’s Liability 3 Sensor Accuracy 1...
  • Page 34 5TE Operator’s Manual Index Specifications 1 Temperature 6, 18 Troubleshooting 24 Vertical Installation 21 Volumetric Water content 6 Warranty Information 3...

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