Table of Contents
Summary of Contents for EIJKELKAMP SM150-UM-1
- Page 1 User Manual for the SM150 Soil Moisture Sensor P.O. Box 4, 6987 ZG Giesbeek Nijverheidsstraat 30, 6987 EM Giesbeek, The Netherlands T +31 313 880200 F +31 313 880299 E info@eijkelkamp.com SM150-UM-1 http://www.eijkelkamp.com M1.14.23.E...
- Page 2 See page 31. Design changes Delta-T Devices Ltd reserves the right to change the designs and specifications of its products at any time without prior notice. User Manual Version: SM150-UM-1 Nov 2011 P.O. Box 4, 6987 ZG Giesbeek Nijverheidsstraat 30,...
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Page 3: Table Of Contents
Contents Introduction Description Features Dimensions Parts list Care and Safety How the SM150 works Operation Cable Connections Installation HH150 Meter HH2 Meter Logger connections and configuration GP1 Logger DL6 Logger DL2e Logger Other data loggers Calibration Soil calibration Sensor calibration Soil moisture reading Troubleshooting Technical Reference... - Page 4 References Appendix 1 Soil-specific Calibration Laboratory calibration for non-clay soils Laboratory calibration for clay soils Technical Support Index Introduction SM150 User Manual 1...
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Page 5: Introduction
Introduction Description The SM150 measures soil moisture content. Its sealed plastic body is attached to two sensing rods which insert directly into the soil for taking readings. A waterproof plug connects to a choice of signal cables. Both extension cables and extension tubes can be used. The soil moisture output signal is a differential analogue DC voltage. -
Page 6: Dimensions
Dimensions Cable connector sealed to IP68 M12, 5 pin, male Thread ¾inch BSP for connecting to Extension Tube(s) 22mm 40 mm Introduction SM150 User Manual 1... -
Page 7: Parts List
Parts list Your shipment may include the following: HH150 soil moisture sensor HH150 +SM150 Kit HH150 includes 1m cable, Connects to SM150 SMCS/d-HH2 1.5m cable Connects SM150 to HH2 SMSC/sw-05 5m cable 100mm flying leads Connect to GP1 & DL6 loggers SMSC/lw-05 5m cable 200mm flying leads Connect to DL2 data logger... -
Page 8: Care And Safety
Care and Safety The rods of the SM150 are sharp in To prevent personal injury and damage to order to ease insertion. Care must be the probe always store and transport the SM150 in this protective tube taken and handling precautions followed. -
Page 9: How The Sm150 Works
How the SM150 works When power is applied to the SM150..it creates a 100MHz waveform (similar to FM radio). The waveform is applied to a pair of stainless steel rods which transmit an electromagnetic field into the soil. The water content of the soil surrounding the rods..dominates its permittivity. -
Page 10: Operation
Operation Cable Connections HH150 includes 1m cable, Connects to SM150 SMCS/d-HH2 1.5m cable Connects SM150 to HH2 Logger extension cables EXT/5W-05 EXT/5W-10 10m EXT/5W-25 25m For wiring colour codes see Logger connections and configuration on page 14 Take care when attaching cables to ensure that the connectors are clean, undamaged and properly aligned before pushing the parts together. -
Page 11: Installation
Installation Surface installation and spot measurements Clear away any stones. Pre-form holes in very hard soils before insertion. Push the SM150 into the soil until the rods are fully inserted. Ensure good soil contact. If you feel strong resistance when inserting the SM150, you have probably hit a stone. -
Page 12: Hh150 Meter
HH150 Meter Connect the SM150 to the HH150 meter. With the meter OFF, press the right off – menu button. This wakes and allows you to set the meter to display readings - either as % volumetric water content of Mineral or Organic soils, or to show the sensor output in Volts. -
Page 13: Hh2 Meter
HH2 Meter This assumes you have version 2.6 or later for both the PC software HH2Read and the HH2 firmware (see foot of page). Connect the SM150 to the HH2 meter. Press to turn the meter on, and if necessary press again until the HH2 displays the start-up screen. -
Page 14: Logger Connections And Configuration
Logger connections and configuration GP1 Logger 4 SM150s can connect to a GP1, but results recorded via channels 3&4 are less accurate. Requirements GP1 logger (with v1.47 firmware or later) PC running DeltaLINK (version 2.6 or later) SM150 with SMSC/sw-05 cable Channel 1 and 2 wiring SM150 wire Colour GP1 terminal CH1/2... -
Page 15: Dl6 Logger
DL6 Logger 6 SM150s can be connected to a DL6. Each is wired as a differential, powered sensor. These details illustrate connection to channel 6 SM300 wiring Colour DL6 terminal Power 0V brown Power V+ white Signal HI blue Signal LO black Cable shield green... -
Page 16: Dl2E Logger
DL2e Logger Up to 60 SM150s can be connected to a DL2e. Each moisture sensor is connected as a differential, powered sensor. These details illustrate connection to channel 58 using a LAC1 input card configured in 15-channel mode, and warm-up channel 63: SM150 wiring Colour DL2e terminal... -
Page 17: Other Data Loggers
Other data loggers The SM150 soil moisture output should be connected as a differential, powered sensor. Configure the logger to convert the SM150 readings from milliVolts into soil moisture units by using either :- Polynomial conversion on page 22 or Linearisation table conversion on page 23 Note: Output signals in the range 0 to 1.0 volts from the SM150, corresponding to ~0 to 60% water content in mineral soils –... -
Page 18: Calibration
Calibration mineral The SM150 is provided with general calibrations for organic soils which can be used to convert the output from the sensor directly into soil moisture when used with Delta-T loggers and moisture meters. This section explains how these calibrations work, how to adapt them for other soils and how to provide calibrations for other data loggers. -
Page 19: Soil Calibration
Soil calibration Damp soil is essentially a mixture of soil particles, air and water, and together these components determine its dielectric properties, including the refractive index . The refractive index of the mixture is approximated simply by adding the contributions from the individual components [ref 4.]. - Page 20 General soil calibrations Most soils can be characterised simply by choosing one of the two general calibrations we supply, one for mineral soils (predominantly sand, silt and clay) and one for organic soils (with a high organic matter content). Mineral soils Organic soils General soil calibrations Mineral...
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Page 21: Sensor Calibration
Sensor calibration Each SM150 is individually adjusted to provide consistent dielectric performance: SM150 dielectric performance √ε 0.00 0.20 0.40 0.60 0.80 1.00 1.20 SM150 output (V) This response can be approximated either by a polynomial (below) or by a linearisation table (see next page): Polynomial (for use over the full range of SM300 readings) √... -
Page 22: Soil Moisture Reading
Linearisation table (for use over the full range of SM150 readings) 0.000 1.000 0.300 3.576 0.600 5.101 0.900 6.778 1.200 8.924 0.075 1.942 0.375 3.964 0.675 5.503 0.975 7.232 1.275 9.743 0.150 2.620 0.450 4.337 0.750 5.917 1.050... - Page 23 Linearisation table conversion The conversion from SM150 reading (Volts) to soil moisture or %vol) can be accomplished by a look-up table. The following table lists the values used for the DL2e data logger: Mineral Organic Mineral Organic Soil Soil soil soil moisture...
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Page 24: Troubleshooting
Troubleshooting Always try to identify which part of the measurement system is the source of the difficulty. For the SM150 this may fall into one of the following areas: The measurement device What equipment is being used to read the probe output? ... - Page 25 Functional check Air reading Hold the SM150 in air and away from other objects and take a reading using an HH150 or HH2 meter or voltmeter or a logger with no more than 5m of cable. Warning: Do not touch the pins A typical electrostatic discharge from your body can create a temporary -10mV offset in sensor readings lasting an hour.
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Page 26: Technical Reference
Technical Reference Specifications 3.0% vol over 0 to 70 % vol and 0-60°C Accuracy Measurement range 0 to 100% vol but less accurate above 70%vol 5% vol over 100 to 1000 mS.m Salinity error and 0-60% vol Conductivity response See page 27 Temperature sensitivity See page 28 Sampling volume... - Page 27 Conductivity response This chart shows how salinity affects the output of the soil moisture sensor at various soil moisture levels. SM150 conductivity response at different water contents 100% (water) ~60% ~45% ~38% ~30% ~20% Typical artificial substrate conditions Typical soil conditions Conductivity EC (mS.m non-...
- Page 28 Temperature response of soil moisture readings The effect of temperature on the SM150 soil moisture readings in any particular soil will depend on a combination of effects: The SM150 soil moisture electronics has very low temperature sensitivity, and makes a negligible contribution to the overall sensitivity.
- Page 29 Sampling Volume The SM150 is most sensitive to signals very close to the two rods, but a small proportion of the signal reaches up to 50mm from the rods. SM150 field of sensitivity surrounding the rods 0.08 0.07 0.06 0.05 0.04 0.03 0.02...
- Page 30 If the SM150 is inserted too close to the wall of a plant pot the sensing field can “see” outside the pot. This behaviour is shown in the graph below. For best results keep a gap of at least 25mm (1 inch) between the body of the sensor and the wall of the plant pot.
- Page 31 Electromagnetic Compatibility (EMC) General information SM150 is a Class A product, intended for operation in non- residential environments. Only use cables and accessories authorised by Delta-T (sensor cables from other sources for example may adversely affect product performance and affect quality of results). If possible route cables along the soil surface or bury them –...
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Page 32: Definitions
Definitions Volumetric Soil Moisture Content is defined as where V is the volume of water contained in the sample and V is the total volume of the soil sample. The preferred units for this ratio are m , though %vol is frequently used. - Page 33 Organic and Mineral soil definitions: The general calibrations have been optimised to cover a wide range of soil types, based on the following definitions: Soil type optimised use for bulk use for around organic density bulk organic contents: range: densities: content: (g.cm (g.cm...
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Page 34: Sm150 User Manual
References Gaskin, G.J. and J.D. Miller, 1996 Measurement of soil water content using a simplified impedance measuring technique. J. Agr. Engng Res 63, 153-160 Topp, G.C., J. L. Davis and A. P Annan 1980 Electromagnetic determination of soil water content. Water Resour. -
Page 35: Appendix 1
Appendix 1 Soil-specific Calibration This note provides details of 2 techniques for generating soil- specific calibrations: Laboratory calibration for substrates* and non-clay soils Laboratory calibration for clay soils We use the term substrate to refer to any artificial growing medium. Underlying principle Soil moisture content () is proportional to the refractive index of the soil () as measured by the SM150 (see Calibration section). -
Page 36: Laboratory Calibration For Non-Clay Soils
Laboratory calibration for non-clay soils This is the easiest technique, but it‟s not suitable for soils that shrink or become very hard when dry. Equipment you will need: SM150 and meter Soil corer (if doing a calibration for a cohesive soil rather than sand or a substrate) ... - Page 37 Insert SM150 into the sample and record its output in Volts. = 0.350V Dry the sample thoroughly. With mineral soils this is usually achieved by keeping it in the oven at 105°C for several hours or days (the time required depends on the sample size and porosity).
- Page 38 volume, L = 0.25 Calculate a In the wet soil V = V = 0.350 Volts and substituting gives Finally ...
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Page 39: Laboratory Calibration For Clay Soils
Laboratory calibration for clay soils This technique is adapted to avoid the near-impossibility of inserting the SM150 into completely dry clay soil. It requires taking measurements at 2 significantly different, but still damp, moisture levels. Equipment you will need: SM150 and meter ... - Page 40 Insert SM150 into the wet sample and record its output in Volts. = 0.349V Dry the sample until still moist, ~15% water content. Gentle warming can be used to accelerate the process, but take care not to over-dry in places, and allow time for the water content to equilibrate throughout the sample before taking a reading.
- Page 41 Calculations Substituting in the SM150 equation √ provides two dielectric values, and at two known water contents, For the wet Substituting Vw = 0.349 gives √ soil Substituting Vm = 0.180 gives For the moist √ soil √...
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Page 42: Technical Support
Technical Support Terms and Conditions of Sale Our Conditions of Sale (ref: COND: 1/07) set out Delta-T's legal obligations on these matters. The following paragraphs summarise Delta T's position but reference should always be made to the exact terms of our Conditions of Sale, which will prevail over the following explanation. - Page 43 In your enquiry, always quote instrument serial numbers, software version numbers, and the approximate date and source of purchase where these are relevant. Contact details: P.O. Box 4, 6987 ZG Giesbeek Nijverheidsstraat 30, 6987 EM Giesbeek, The Netherlands T +31 313 880200 F +31 313 880299 E info@eijkelkamp.com http://www.eijkelkamp.com...
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Page 44: Index
Index DL6, 15 Air reading, 25 EMC, 31 Extension cables, 10 Cable Connections, 10 Calibration, 18 check, 25 FCC compliance, 31 generalised, 22 Features, 5 sensor, 21, 22 soil, 19, 22 Soil, 35 soil-specific, 35 GP1, 14, 15, 24 Care and safety, 8 Care and Safety, 8 Certification emc, 31... - Page 45 clay, 19, 20, 32, 35, 36, 39 mineral, 18, 20, 22, 36, 37, 40 Organic and Mineral, 33 organic, 18, 20, 22, 33, 37 stony, 11 soil calibrations, 20 Specifications, 2, 26 Parts, 7 Patent, 2 Permittivity, 9, 18, 34 Polynomial conversion, 22 Technical support, 42, 43 Temperature response of soil moisture...
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