W.E.T Sensor type WET-1
Contents
1. W E T Sensor type WET 1 Moisture Meter type HH2 W E T Sensor type WET 1 a Precision Horticulture a Soil Science Research RRS e W E T sensors are used in soils and growing substrates One sensor produces three outputs J T T f T ae N Water content Electrical Conductivity Tem perature The new W E T Sensor type WET 1 from Delta T Devices measures three vital soil properties Water content Electrical conductivity EC and Temperature The W E T Sensor has applications in precision horticulture and soil science research and is usable in both soils and growing substrates see page 2 for details It is unique in its ability to measure pore water conductivity EC which is the EC of the water that is available to the plant Readout and data storage in the field are handled by the HH2 Moisture Meter see page 3 Delta T gratefully acknowledges the partner organisations that have enabled the development of the W E T Sensor Institute of Agricultural and Environmental Engineering IMAG BV P O Box 43 6700 AA Wageningen The Netherlands Tel 31 317 476654 Fax 31 317 425670 Website www imag wag ur nl Designers of the W E T Sensor and the integrated circuit which enables pall IMAG accurate measurement of the permittivity and conductivity of the bulk soil or media Saint Gobain Cultilene B V Hoekenidsehof 1 2665 JZ Postbus 4 2665 ZG Bleiswijk The Netherlands Tel 31 10 5294294 Fax 31 10 522. mS em or yS em Jo y o Soil Permittivity e o d S S a Soil bulk conductivity ECL mS m mS em or yS em d y o But not a typical application for the W E T Sensor Selectable Upgrading older versions of the HH2 Moisture Meter Do you need to upgrade your Moisture Meter The W E T Sensor cannot be used with an older version of the HH2 unless it has been upgraded It makes good sense to upgrade for most other applications too and if your HH2 is not running PROM 2 00 we recommend that you upgrade now The PROM firmware the PC Software and the User Manual have been updated The main improvements are support for new sensor types the provision of a Dataset Import Wizard and the introduction of wider soil specific calibration coefficients for Profile Probe users PROM 2 00 has been fitted in all HH2s made since April 2002 To check your HH2 s PROM version run HH2 Read on your PC and click on the version button How to get your Moisture Meter upgraded NB upgrades have to be performed by Delta T Devices The order description is Q HH2 Moisture Meter Factory Upgrade type HH2 UPGD1 includes installation of new firmware version 2 0 HH2 READ PC Software and provision of latest version of User Manual Please contact Delta T or your local distributor for prices and to make arrangements for returning your HH2 Moisture Meter type HH2 Specification update Representative Specifications are unchanged from those
3. of reading 1800 a or t 10 mS nv1 1500 i E 1200 gt 2 Soil Moisture accuracy specification refer to errors after applying a soil specific calibration within 10 C of calibration temperature accuracy typical 10 reading max errors 20 o0f reading or 20 mS m whichever is greater 900 600 300 Pore water conductivity EC mS m 0 0 1 0 2 0 3 0 4 0 5 0 6 0 7 0 8 0 9 Soil water content 0 m m W E T Substrate Calibrations Upgrade type WET CL 1 The WET sensor is particularly valuable in greenhouse or protected environment applications Special WET CL 1 calibrations can be ordered as a set for a variety of horticultural media mineral wools vertical and horizontal measurement glass wool coir peat based potting mixes and greenhouse mineral soils It should be noted that this upgrade is installed into the HH2 Moisture Meter not into the sensor itself Ordering Information W E T Sensor Kit type WET K1 Comprises WET 1 d 02 W E T Sensor HH2 Moisture Meter including alkaline battery and comms cable spare battery user manuals and WCC2 carrying case WET K1 includes sensor calibrations suitable for a variety of standard soil types W E T Sensor Kit type WET H K2 Comprises WET 1 d 02 W E T Sensor HH2 Moisture Meter incl alkaline battery and comms cable fitted with WET CL 1 W E T substrate calibrations upgrade spare battery user manuals and WCC2 carrying case W E T Se
4. given on page 8 of the Soil and Plant Water Measurement catalogue except for increases in the number of readings stored as detailed below Memory capacity Typical ThetaProbe 227 2186 Profile Probe PR1 6 166 782 Profile Probe PR1 4 221 1042 W E T Sensor 204 1272 Minimum all reading options changed for each reading For HH2 Ordering Information please see page 2 Delta T Devices Ltd 128 Low Road Burwell Cambridge CB5 OEJ UK Fax 44 1638 743155 Tel 44 1638742922 email sales delta t co uk web www delta t co uk WET _HH2_ update 1 doc 18 10 02
5. 94299 Website www cultilene nl Sponsors of research into horticultural media applications and suppliers of horticultural media calibrations Exclusive suppliers of horticultural media calibrations to customers in the Netherlands SAINT GOBAIN Applied Plant Research CULTILENE Division Glasshouse Horticulture Praktijkonderzoek Plant amp Omgeving B V ii APPLIED PLANT RESEARCH former Research Station for Floriculture amp Glasshouse Vegetables P O Box 8 2670 AA Naaldwijk The Netherlands Tel 31 174 636700 Fax 31 174 636835 Website www ppo dio nl Developers of the W E T calibrations for horticultural media 2001 W E T Sensor Specifications Probe Output Range Accuracy Resolution Units Bulk conductivity EC 0 200 mS m Temperature C Permittivity lt 1 1 80 2 5 0 1 no units depends on water content and rO msS m conductivity see graph Environmental Sensor sealed to IP67 Typically 38mA for 2 5 seconds connector sealed to IP65 WET 1 d requires 6 10 Volts Operating temperature 0 to 50 C Frequency 20 MHz Calibration Individual sensor calibrations Dimensions Probe housing 55 x 45 x 10mm supplied amp weight Rods 68mm long x 3mmdia Wt 75g Notes 1 Permittivity is a measure of the dielectric properties of materials soil Pore water conductivity EC Pore water conductivity accuracy 2100 rrr a accuracy typical 5 reading max errors 10
6. can be selected In addition five user defined custom soil calibrations can be entered The HH2 can only be configured for use with a single W E T Sensor Swapping between different W E T Sensors requires access to a PC and takes a few minutes and it is therefore generally preferable to have an HH2 Moisture Meter dedicated to each W E T Sensor Special Calibrations for horticultural media Special WET CL 1 calibrations can be ordered as a set for a variety of horticultural media mineral wools vertical and horizontal measurement glass wool coir peat based potting mixes and greenhouse mineral soils Water Deficit The water deficit capability of the HH2 can be used with the W E T sensor in a similar manner to the Profile Probe and ThetaProbe see previous page Other options User selectable options allow pore water and or bulk conductivity to be displayed and additionally the pemittivity Temperature Compensation Electrical conductivity is a means of estimating the ionic content of soil pore water and as electrical conductivity varies with temperature readings may need to be adjusted to a standard temperature The HH2 provides user selectable temperature compensation HH2 Output options Measurement Theta Profile Equi Probe Probe tensio meter Soil moisture content m m or Vol vw vw 4 Water deficit mm vw vw iw Unconverted mV output A l a S d s Temperature S d S S A S Pore Water Conductivity EC mS m
7. nsor type WET 1 d 02 Combined water content electrical conductivity and temperature probe Includes sensor calibration on 3 5 disk 2m cable with 25 way D connector including voltage regulator For use with HH2 only Moisture Meter type HH2 With integral 25 pin D connector for sensor or PC connection Includes connector cap battery user manual with PC software and RS232 cable assembly NB the HH2 can only be configured for use with a single W E T Sensor Swapping between different W E T Sensors requires access to a PC and takes a few minutes It is therefore generally preferable to have an HH2 Moisture Meter dedicated to each W E T Sensor W E T Substrate Calibrations Upgrade type WET CL 1 Upgrade of HH2 Moisture Meter with W E T substrate calibrations suitable for a variety of horticultural media NB calibrations are factory installed at Delta T premises In the Netherlands WET CL 1 is available exclusively through Saint Gobain Cultil ne B V Moisture Meter toe xz The Moisture Meter type HH2 is a versatile readout unit for use with Delta T soil moisture sensors the Profile Probe ThetaProbe Equitensiometer and W E T Sensor a Holds multiple user defined soil types O Selectable outputs Q Includes PC data collection software Simple versatile operation The HH2 offers impressive functionality in a compact hand held unit designed for field use Readings are displayed on the LCD and can be stored to memory for late
8. oils are supplied with the HH2 These are suitable for use with the ThetaProbe or the Profile Probe The software also permits up to 5 extra user defined soil calibrations to be characterised and stored for later use The active soil type can be switched at any time during the collection of data and can be specified separately for each sensor position on a single profile probe The unconverted millivolt readings can be stored alongside the soil moisture readings Water Deficit Reading This reading indicates the amount of water needed in mm to restore the plot to field capacity across a user defined rooting depth The HH2 automatically calculates the water deficit based on data from a ThetaProbe or the individual sensors of a PR1 within that depth Field capacity or refill point is user defined The HH2 User Manual contains tables of standard soil classifications and their equivalent field capacity values A single HH2 Moisture Meter can be used to read a large number of in situ ThetaProbes or Profile Probes or combinations of both by connection to each sensor in turn Using the HH2 with W E T Sensors The HH2 is able to display and store the 3 outputs produced by the W E T Sensor water content electrical conductivity and soil temperature The outputs can be stored in the HH2 for subsequent downloading to a PC using HH2 Read PC software In the W E T Sensor mode standard calibrations for Mineral Organic Clay or Sand media
9. r download to a PC Up to 2100 time stamped readings can be stored The unit can be operated with one hand for convenience in the field Each time stamped reading includes a unique sample number a plot identification number A to Z and a sensor location number 1 to 255 Data is transferred to a PC using the RS 232 cable provided with each unit The HH2Read Windows PC software provides a data import wizard for direct download into Excel or other PC spreadsheet packages or into irrigation scheduling programs Alternatively data can be downloaded in comma separated ASCII data file CSV format Using the HH2 with ThetaProbes and Profile Probes ThetaProbes When used with ThetaProbes the HH2 displays and stores single point soil moisture measurements This creates a compact system for obtaining soil moisture readings on the move and is best suited to surface measurements Profile Probes When used with Profile Probes the HH2 reads and stores the soil moisture content at either 4 or 6 depths simultaneously and can calculate the water deficit at each depth The HH2 auto detects the number of sensors present in each Profile Probe This combination of Profile Probe and Moisture Meter provides a portable low cost system for quickly collecting soil moisture profile data Readings can be taken wherever access tubes have been installed kkkkkkkkkkkkkkkkk User defined soil types Standard generalised calibrations for mineral and organic s
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