SM300 user manual
Contents
1. 2 719 2 920 0 480 0 540 0 600 0 660 Linearisation table conversion 3 139 0 720 4 269 0 960 6 001 3 385 0 780 4 601 1 020 6 890 3 659 0 840 4 966 1 080 8 282 3 955 0 900 5 406 1 140 10 531 The conversion from ML3 reading Volts to soil moisture 6 m m or vol can be accomplished by a look up table The following table lists the values used for the DL2e data logger Soil moisture vol y 0 4 8 12 16 20 24 28 32 36 40 44 48 Mineral soil Volts 2 090 0 096 0 156 0 232 0 326 0 427 0 514 0 591 0 659 0 724 0 783 0 838 0 886 0 924 ML3 User Manual 1 0 Organic Soil Mineral Organic soil moisture soil soil Volts vol Volts Volts 2 090 52 0 956 0 887 0 048 56 0 982 0 922 0 097 60 1 004 0 951 0 153 64 1 023 0 976 0 220 68 1 040 0 997 0 304 72 1 054 1 016 0 396 76 1 068 1 032 0 482 80 1 080 1 046 0 557 84 1 091 1059 0 620 88 1 101 1 071 0 683 92 1 110 1 082 0 740 96 eS 1 092 0 795 100 1 127 1 101 0 844 104 2 090 2 090 Operation 23 Troubleshooting Always try to identify which part of the measurement system is the source of the difficulty For the ML3 this may fall into one of the following areas The measurement device What equipment is being used to read the probe output A Delta T HH2 Moisture Meter Note the HH2 does not measure ML3 temperature A Delta T data logger such as the GP1 GP2 DL6 or DL2e Check Versions Check you have the correct ve2. 35 soil specific 35 Care and safety 8 Care and Safety 8 Certification emc 29 Civil engineering 42 climate 42 Conductivity response 27 Connections 12 contamination 42 Conversions linearisation table 20 21 polynomial 20 21 Copyright 2 D Data logger 16 23 24 25 DL2e 23 24 DL6 24 GP1 14 24 ML3 User Manual 1 0 other 16 Definitions 30 Description 5 Dielectric performance 21 refractive index 18 19 35 Dimensions 6 DL6 14 E EMC 29 Extension cables 10 F FCC compliance 29 Features 5 G Global warming 42 GP1 13 14 24 GP2 12 H HH2 7 17 18 24 25 hydrogeology 42 Installation buried 11 insertion rod 11 surface 11 index L Linearisation table 23 volts to vol 16 23 M Meter 24 Moisture content 5 9 32 35 O Organic and Mineral 31 p Parts 7 Permittivity 9 18 32 Polynomial conversion 22 R References 32 Regulatory information 29 Rods 8 9 11 Sales code 7 Salinity 31 Servicing 34 ML3 User Manual 1 0 SMSC Iw 05 43 Soil clay 19 20 30 35 36 39 mineral 18 20 22 36 37 40 organic 18 20 22 31 37 stony 11 soil calibrations 20 Specifications 2 26 T Technical support 33 34 Temperature cable length correction 16 43 Temperature response of soil moisture readings 28 Temperature sensor cable length correction 44 Temperature Sensor Lookup Table 45 Troubleshooting 24 V
3. Volumetric Soil Moisture 30 W Warning Care and Safety 8 Warning 25 Index
4. 578V 183 44V 184 78V 68 017V provides two dielectric values Vew and Vem at two known water contents and Omn For the wet Substituting Vw 0 572 gives Ve 3 53 do a0 for 8 743 3 627 2 463 5 0 25 Soll For the moist Substituting Vm 0 348 gives Ve 2 68 do iOm For 693 2 627 2 463 5 0 14 Calculatea Then a Je Je 0 0 7 86 d 7 86 soil w Calculate a and a Je a 0 1 56 do 1 56 Result a 7 86 do 1 56 In this example this soil is now calibrated You can now use these two numbers in place of the standard mineral or organic calibration factors to convert ML3 readings into volumetric water content using Ve a a xO See also page Underlying principle on page 35 ML3 User Manual 1 0 Appendix 2 The ML3 Temperature Sensor Soil moisture content is used with the measurement of soil temperature in several major application areas including the following Global warming and climate studies Soils contain more than four times as much carbon as the CO2 in the atmosphere and each year they release about ten times as much carbon through soil respiration as the combined release through burning fossil fuels Soil respiration rates are particularly sensitive to changes in both temperature and the moisture content of the soil Soils also have a significant interaction with climate as they store and release heat soil temperature p
5. 60 co Z 4 0 5 Ss SI A an nada Offset ao 0 0 0 0 0 2 0 4 0 6 0 8 Soil moisture m m Note that do VEay soi 1S USUally between 1 3 to 2 3 a corresponds approximately to 4 e l and usually takes a value about 8 0 Real soil values for a and a can vary significantly from these guidelines when they are affected by other factors in particular bound water in clay may result in higher values of a4 ML3 User Manual 1 0 Operation 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 8 0 4 Y lt Mineral a Kx 604 Organic v gt 404 prar O D D 204 V 0 0 T T T 0 0 0 2 0 4 0 6 0 8 Soil Moisture m m These values have been used to generate the polynomial conversions and linearisation tables in the Soil moisture reading section Soil specific calibration Instead of adopting these general calibrations you may wish to determine specific calibration values of and a for your soil This procedure is fairly straightforward if you can get access to standard laboratory equipment and is described in detail in Appendix 1 on page 34 Soil specific calibration can significantly improve the accurac
6. References Technical Support Appendix 1 Soil specific Calibration Laboratory calibration for non clay soils Laboratory calibration for clay soils Appendix 2 The ML3 Temperature Sensor ML3 Temperature Measurement Effect of Temperature on Water Permittivity Resistance to Temperature Lookup Table Index 26 30 32 33 35 35 36 39 42 42 43 44 45 46 Introduction Introduction Description The ML3 measures soil moisture content and temperature Its sealed plastic body is attached to four 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 This is converted to soil moisture by a data logger or meter using the supplied general soil calibrations It can also be calibrated for specific soils Features Soil moisture accurate to 1 Soil temperature to 0 5 C over 0 40 C Low salinity sensitivity Excellent stability Minimal soil disturbance Easy installation at depth in augered holes Waterproof connector to IP68 Rugged weatherproof and can be buried Good electrical immunity Choice of cabling system options Cable connector cylindrical profile and extension tube design simplifies removal for servicing See also Specifications on page 26 1 A data logger is required
7. corrected for 18 mA ML3 supply current GP2 GP1 and DL6 loggers The ML3 Temperature sensor type in DeltaLINK 3 performs the supply current correction DL2e Logger The linearization table for the S3T sensor code ML3 Temperature provides supply current correction for the SMSC lIw 05 5m logger cable ONLY Extension cables and other cable lengths Create your own custom sensor type s and linearization tables as described in Ls2Win Help topic How to Add or modify a sensor type in the sensor library Enter corrected resistance values R for each linearization table point R R5 0 059 x Lex kQ See footnote or R R5 0 9 x Re 0 297 KQ where R5 value supplied in the table for the ML3 Temp 5m sensor type Lex length of extension cable excluding the 5m of SMSC Iw 05 cable Rc total cable resistance including resistance of SMSC lIw 05 cable if fitted 1 Note This equation only applies to Delta T ML3 cables ML3 User Manual 1 0 Appendix 2 Other loggers If your logger can be programmed so that the soil moisture and temperature readings can be taken sequentially i e the sensor is not powered during the temperature reading then the temperature can be obtained directly from the response curve on page 45 Otherwise correct the resistance reading before applying the response curve You need to know the resistance of the Power OV wire in the ML3 cable Rc and
8. significantly different but still damp moisture levels Equipment you will need ML3 and meter Soil corer Heat resistant beaker gt 500ml Weighing balance accurate to lt 1g Temperature controlled oven Process Notes and example Collect a wet sample of the clay soil 25 to 30 water content would be ideal This sample needs to be unchanged from its in situ density to be gt 400ml to have the correct dimensions to fit the beaker and to be generally uniform in water content This is most easily done with soil corer Measure the volume occupied by the sample L 463 5ml Weigh the wet sample including the beaker Wua 743 3g ML3 User Manual 1 0 Appendix 1 39 Insert ML3 into the wet sample and record its output in Volts Vy 0 572V 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 Reweigh Wn 693 2g Re measure with the ML3 Vm 0 348 V Dry the sample thoroughly With clay 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 Weigh the dry sample in the beaker W 627 2g ML3 User Manual 1 0 Appendix 1 40 Calculations Substituting in the ML3 equation Ve 1 0 6 175V 6 303V 73
9. User Manual for the ML3 ThetaProbe Soil Moisture Sensor AT Delta T Devices Ltd Notices Patents The ML3 ThetaProbe has been jointly developed by The Macaulay Land Use Research Institute and Delta T Devices Ltd and uses novel measurements They are subject to the following patents UK GB2300485B US 9804976 Copyright All parts of the ML3 ThetaProbe design and documentation are the exclusive right of Delta T Devices and covered under copyright law 2013 Delta T Devices Ltd EMC Compliance see page 29 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 ML3 UM 1 0 April 2013 Delta T Devices Ltd Tel 44 1638 742922 130 Low Road Fax 44 1638 743155 Burwell Cambridge CB25 0E UK email sales delta t co uk web www delta t co uk Contents Introduction Description Features Dimensions Parts list Care and Safety How the ML3 works Operation Cable Connections Installation Logger connections and configuration GP2 GP1 DL6 DL2e Other data loggers HH2 Meter Calibration Soil calibration sensor calibration Soil moisture reading Troubleshooting Technical Reference Specifications Volumetric water content ML3 User Manual 1 0 o O1 17 18 18 21 22 24 26 26 26 Introduction ML3 User Manual 1 0 Temperature Definitions
10. aLINK version 3 or later A free upgrade can be obtained from www delta t co uk or from the Software and Manuals DVD ML3 User Manual 1 0 Operation 13 DL6 6 ML3s can be connected to a DL6 Each ML3 is wired as a differential powered sensor A DL6 logger can only read one ML3 temperature sensor These details illustrate connection to channels 6 amp 7 ML3 wiring Colour DL6 terminal Power OV brown OV Power V white V Soil Moisture IN Signal HI ae Soil Moisture IN Signal LO meee Temperature grey RES IN Cable shield green Z777 In DeltaLINK configure channel 6 as type ML3 and channel 7 as a type ML3 Temperature sensor See also the DL6 Quick Start Guide and the DeltaLINK online Help The DL6 logger needs the PC logger software DeltaLINK version 3 or later A free upgrade can be obtained from www delta t co uk or from the Software and Manuals DVD ML3 User Manual 1 0 Operation 14 DL2e Up to 60 ML3s can be connected to a DL2e logger if not using the temperature sensor channel Up to 30 ML3s can be connected if also reading the temperature sensor Each ML3 is connected as a differential powered sensor These details illustrate connection to Channels 57 and 58 using a LAC1 input card configured in 15 channel mode and warm up channel 63 ML3 wiring Colour DL2e terminal Power OV brown CH62 or 61 Power V white CH63 NO Soil Moisture Signal HI blue CH58 Soil Moistu
11. and expansion lid GP2 G5 LID These details illustrate connection to Channels 1 and 2 ML3 wiring Colour GP2 terminal Power OV and Thermistor LO brown CH1 PGND Power V white CH1 PWR Soil Moisture Signal HI blue CH1 Soil Moisture Signal LO black CH1 Thermistor HI grey CH2 and CH2 Cable shield green CH1 PGND For configuration details see the DeltaLINK 37 software ML3 sensor Info Panel Help or the GP2 User Manual Download the latest version of the DeltaLINK logger software from www delta t co uk or from our Software and Manuals DVD The GP2 logger needs the PC logger software DeltaLINK 3 This can be obtained from www delta t co uk or the Software and Manuals DVD ML3 User Manual 1 0 Operation 12 GP1 Two ML3s can connect to each GP 1 Each ML3 is wired as a differential powered sensor These details illustrate connection to Channels 1 and 3 ML3 wiring Colour GP7 terminal Power OV and DONA CH1 GND Thermistor LO or Temp GND Power V white CH1 PWR Soil Moisture Signal HI d ents Soil Moisture black CH1 Signal LO Temperature grey Temp3 IN Cable shield green CH1 GND Using the DeltaLINK logger software configure channel 1 or 2 as sensor type ML3 and channel 3 or 4 as an ML3 Temperature sensor See also GP1 Quick Start Guide and the DeltaLINK on line Help The GP1 logger needs the PC logger software Delt
12. ater contents The last two effects partially offset each other but in soil conditions where one or the other effect dominates the ML3 will appear to have a significant temperature response This illustration is based on the model in reference 7 see page 32 Illustrating the temperature dependence of ML3 readings in clay soil o uo ome 04 am 0 3 ome 0 2 0 1 bound water 0 4 M E mMm E w c w U nn ro vV Y io b a a lt 20 30 Soil temperature C Note ice has a quite different refractive index from water so ML3 soil moisture readings cannot be interpreted reliably when inserted into soil below 0 C ML3 User Manual 1 0 Technical Reference 28 Electromagnetic Compatibility EMC General information ML3 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 this also reduces possible trip hazard and animal damage Do not modify the product or its supplied accessories See also ML3 EMC Guidance on the Software and Manuals DVD Issue 3 Regulatory information Europe This device conforms to the essential requirements of the EMC directive 2004 108 EC based on the fol
13. cy of the ML3 temperature sensor itself The two only become comparable below 15C 9 DL2e logger users can apply a correction in the Ls2Win logging software for cable lengths gt 5m ML3 User Manual 1 0 Technical Reference Conductivity response This chart shows how salinity affects the output of the soil moisture sensor at various soil moisture levels ML3 Conductivity response at different water contents 1 4 1 2 Water 10 content 100 a 55 08 ae O 35 S oR 25 17 i MR O ffl l l 0 0 0 100 200 300 400 500 600 Conductivity EC mS m slightly saline Classification of salinity ML3 User Manual 1 0 Technical Reference 2 7 Temperature response of soil moisture readings The effect of temperature on the ML3 soil moisture readings in any particular soil will depend on a combination of effects The ML3 soil moisture electronics has very low temperature sensitivity and makes a negligible contribution to the overall sensitivity The refractive index of water Vs see Calibration section reduces as the temperature increases This produces a negative temperature response particularly in soils or substrates with high water content Water that is bound to the surface of soil particles has a much lower refractive index than free water The percentage of bound water decreases with temperature and this produces a positive temperature response particularly in clay soils at lower w
14. ervices if the delay or failure was due to any cause beyond the Delta T s reasonable control ML3 User Manual 1 0 Technical Support Service Repairs and Spares Users in countries that have a Delta T distributor or technical representative should contact them in the first instance Spare parts for our own instruments can be supplied and can normally be despatched within a few working days of receiving an order Spare parts and accessories for products not manufactured by Delta T may have to be obtained from our supplier and a certain amount of additional delay is inevitable No goods or equipment should be returned to Delta T without first obtaining the return authorisation from Delta T or our distributor On receipt of the goods at Delta T you will be given a reference number Always refer to this reference number in any subsequent correspondence The goods will be inspected and you will be informed of the likely cost and delay We normally expect to complete repairs within one or two weeks of receiving the equipment However if the equipment has to be forwarded to our original supplier for specialist repairs or recalibration additional delays of a few weeks may be expected For contact details see below Technical Support Users in countries that have a Delta T distributor or technical representative should contact them in the first instance Technical Support is available on Delta T products and systems Your initial enq
15. establish whether your logger uses voltage or current excitation for resistance measurement Voltage Excited You need to know the excitation voltage Vref reference resistance Rref The correct resistance is given by the equation R a0 a1 Rmeas Where a0 Ic Rc Rref Vref a1 1 Ic Rc Vref Ic 18 mA ML3 sensor supply current For Delta T EXT 5W xx series cables Rc 0 066 Q m For the SMSC Iw 05 5m logger cable Re 0 33 Q Current Excited You need to know the excitation current lex The corrected resistance is given by the equation using terms defined above R Rmeas Ic Rc lex Effect of Temperature on Water Permittivity See Temperature response of soil moisture readings on page 28 ML3 User Manual 1 0 Appendix 2 Resistance to Temperature Lookup Table Temperature degrees C ML3 Resistance to Temperature Conversion Chart 100 Resistance kOhms 40 20 0 20 40 60 80 Temperature degrees C Note This table has been optimised for use as a look up table To minimise linear interpolation errors the data points fall either side of the manufacturers specified sensor response curve This helps optimise the overall accuracy of readings ML3 User Manual 1 0 Appendix 2 Index A Agriculture 42 Air reading 25 Auger 7 C Cable Connections 10 Cable length correction 43 Calibration check 25 generalised 22 sensor 21 22 soil 19 22 Soil
16. 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 Process ML3 and meter Soil corer if doing a calibration for a cohesive soil rather than sand or a substrate Heat resistant beaker gt 0 5 litre Weighing balance accurate to lt 1g Temperature controlled oven for mineral soils or substrates Notes and example Collect a damp sample of the soil or substrate This sample needs to be unchanged from its in situ density to be gt 0 4 litre to have the correct dimensions to fit the beaker and to be generally uniform in water content For cohesive soils this is most easily done with a soil corer Sandy soils can be poured into the beaker but you should take the subsequent measurements immediately as the water will quickly begin to drain to the bottom of the beaker Compressible soils and composts often require measurement of the in situ density and then need to be carefully reconstituted at that density within the beaker Measure the volume occupied by the sample L 463 5ml Weigh the sample including the beaker Wy 743 3g ML3 User Manual 1 0 Appendix 1 36 Insert ML3 into the sample and record its output in Volts Vy 0 572V 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 sa
17. for temperature measurements ML3 User Manual 1 0 Introduction Dimensions Signal cable connector IP68 M12 5 pin Extension tube connector inch BSP thread dm 39 8 mm _ gt ML3 User Manual 1 0 Introduction 6 Parts list Your shipment may include the following ML3 ML3 sensor with Quick Start Guide SMSC d 0 9m cable connects to HH2 HH2 meter via 25 way D connector 5m cable with SMSC sw 100 mm flying leads 05 for GP2 GP1 or DL6 logger 5m cable with SMSC lw 05 200mm flying leads for DL2e logger EXT 5W 05 5 10 and 25m extension EXT 5W 10 cables IP68 M12 EXT 5W 25 connectors ML EX50 50 and 100cm Extension MLIEX100 Tube SM AUG 45mm spiral auger 100 1 2m long ML3 User Manual 1 0 Introduction ML3 sensor HH2 meter cable SMSC d HH2 Insertion kit ML INK1 4 spare steel pins spare battery carry case HHCC3 HH2 manual ML3 Quick Start Care and Safety To prevent personal injury and damage to the probe always store and transport The rods of the ML3 are sharp in the ML3 in this protective tube order to ease insertion Care must be taken and handling precautions CAUTION followed SHARP PINS Take care when attaching cables to ensure that the connectors are clean undamaged and properly aligned before pushing the parts together Do not pull the ML3 out of the soil by its cable If you feel strong resistance when inserting the ML3 into soil it
18. ing soil moisture content Journal of Soil Sci 44 1 9 4 White l J H Knight S J Zegelin and Topp G C 1994 Comments on Considerations on the use of time domain reflectometry TDR for measuring soil water content by W R Whalley Journal of Soil Sci 45 503 508 5 Roth C H M A Malicki and R Plagge 1992 Empirical evaluation of the relationship between soil dielectric constant and volumetric water content as the basis for calibrating soil moisture measurements Journal of Soil Sci 43 1 13 6 Knight J H 1992 sensitivity of Time Domain Reflectometry measurements to lateral variations in soil water content Water Resour Res 28 2345 2352 7 Or D and J M Wraith 1999 Temperature effects on soil bulk dielectric permittivity measured by time domain reflectrometry A physical model Water Resour Res 35 371 383 ML3 User Manual 1 0 References 32 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 Delta T warrants that the goods will be free from defects arising out of the materials used or poor workmanship for a period of twelve months from the date of delivery Delta T shall be under no liability in respect of any defect arising f
19. ion P where p is the density of water 1g cm E M Ps and p is the bulk density of the sample 7 s ML3 User Manual 1 0 Technical Reference 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 organic density bulk contents range densities g cm g cm Note C denotes percentage Carbon and is a measure of organic content Salinity The preferred SI units for ionic conductivity are mS m where S is Siemens the unit of electric conductance ohm The following conversions apply 1mS m 0 01 dS m 0 01 mS cm 10 uS cm Soil salinity can be classified using the following descriptive categories non slightly moderately saline saline saline 4 Classification of salinity See also http www land vic gov au DPI Vro vrosite nsf pages water spotting soil salting class ranges s1 ML3 User Manual 1 0 Technical Reference 31 References q1 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 2 Topp G C J L Davis and A P Annan 1980 Electromagnetic determination of soil water content Water Resour Res 16 3 574 582 3 Whalley W R 1993 Considerations on the use of time domain reflectometry TDR for measur
20. is likely you have encountered a stone Stop pushing and re insert at a new location Avoid touching the rods or exposing them to other per sources of static damage particularly when powered up Keep the ML3 in its protective tube when not in use ML3 User Manual 1 0 Introduction e 8 How the ML3 works When power is applied to the ML3 It creates a 100MHz waveform similar to FM radio 7 Aap The waveform is applied to an array of stainless steel Aff rods which transmit an electromagnetic field into the soil gt The water content of the soil surrounding the rods dominates its permittivity A measure of a material s response to polarisation in an electromagnetic field Water has a permittivity 81 compared to soil 4 and air 1 The permittivity of the soil has a strong influence on the applied field V which is detected by the ML3 resulting in a stable out voltage output that acts as a simple sensitive measure of soil moisture content ML3 User Manual 1 0 Introduction 9 Operation Cable Connections brown white blue black grey green HH2 Extension Logger cable cables cables bm 5m with 0 9m 100 or 200 10m mm bare 25m leads Power OV Power V Soil Moisture Signal HI Soil Moisture Signal LO Temperature Cable shield Take care when attaching cables to ensure tha
21. lowing test standards EN61326 1 2006 Electrical requirement for measurement control and laboratory use EMC requirements Group 1 Class A equipment emissions section only EN61326 1 2006 Electrical requirement for measurement control and laboratory use EMC requirements Basic Immunity immunity section only FCC compliance USA This device conforms to Part 18 of FCC rules Industrial Scientific amp Medical Equipment Note with reference to FCC Part 18 115 Elimination and investigation of harmful interference a The operator of the ISM equipment that causes harmful interference to radio services shall promptly take appropriate measures to correct the problem ML3 User Manual 1 0 Technical Reference Definitions Volumetric Soil Moisture Content is defined as where V is the volume of water contained in the 0 sample and S Vs is the total volume of the soil sample The preferred units for this ratio are m m though vol is frequently used Soil Moisture Content varies from approx 0 02 m m for sandy soils at the permanent wilting point through approx 0 4 m m for clay soils at their field capacity up to values as high as 0 85 m m in saturated peat soils Gravimetric Soil Moisture Content is defined as 0 My g g where M is the mass of water in the sample Ms and M is the total mass of the dry sample To convert from volumetric to gravimetric water content use the equat
22. mple size and porosity For organic soils and composts it s usual to air dry the sample to avoid burning off any volatile factions Weigh the dry sample in the beaker W 627 2g Re insert the ML3 into the dry sample and record this reading Vo 0 089V Calculate ao For the ML3 In the dry soil V Vo 0 089 Volts Substitute this into the equation Ve 1 0 6 175V 6 303V2 73 578V2 183 44V4 184 78V 68 017V gives 4 1 56 Since o 0 this is the value needed for ao do 1 56 Calculate 6 The water content of the wet soil G can be calculated from the weight of water lost during drying Ww Wo and its volume Ls ML3 User Manual 1 0 Appendix 1 37 6 W W L 743 3 627 2 463 5 0 25 0 0 25 Calculate a In the wet soil V Vy 0 572 Volts and substituting gives JE 3 53 Finally a Je fe 0 0 3 53 1 56 0 25 0 7 87 a 7 87 Result Ay 1 56 d 7 87 In this example this soil is now calibrated You can now use these two numbers in place of the standard mineral or organic calibration factors to convert ML3 readings into volumetric water content using Je a a x0 See also Underlying principle on page 35 ML3 User Manual 1 0 Appendix 1 Laboratory calibration for clay soils This technique is adapted to avoid the near impossibility of inserting the ML3 into completely dry clay soil It requires taking measurements at 2
23. or later for both the PC software HH2Read and the HH2 firmware see foot of page E ai J Connect the ML3 to the HH2 meter Press Esc to turn the meter on and if necessary press again until the HH2 displays the start up screen Set the meter to read from an ML3 Press and scroll down to the Device option Press Set again and scroll down to select ML3 Press Set to confirm this choice Make sure the HH2 is correctly configured for your soil type At the start up screen press Set and scroll down to the Soil Type option Press Set again and scroll down to the appropriate soil type use Mineral for sand silt or clay soils or Organic for peaty soils Press Set to confirm this choice Choose the units you want for displaying readings At the start up screen press Set and scroll down to the Display option Press Set again and scroll down to select units Press Set to confirm this choice Press to take a reading Press to save or Esc to discard the reading Remove the ML3 from the soil and move to a new location If you have saved data connect your HH2 to a PC and run HH2Read to retrieve the readings See also Support for the ML3 Soil Moisture Sensor with an HH2 and HH2 User Manual and HH2 User Manual Addendum to V4 ML3 Note the HH2 does not display or store ML3 temperature readings Note For an upgrade contact Delta T ML3 User Manual 1 0 Operation 17 Calibration The ML3 is p
24. re Signal LO black CH58 Temperature grey CH57 and CH57 Cable shield green CH61 or 62 Configure the chosen DL2e logger channels by selecting the appropriate S3M and S30 sensor types for mineral and organic soils and S3T for the temperature sensor type listed in the Ls2Win sensor library See the DL2e User Manual and the Ls2Win online help gt You need a PC running Ls2Win version 1 0 SR10 or later A free upgrade can be obtained from www delta t co uk or from the Software and Manuals DVD ML3 User Manual 1 0 Operation 15 Other data loggers The ML3 should be connected as a differential powered sensor Configure the logger to convert the ML3 readings from milliVolts into soil moisture units by using either Polynomial conversion on page 22 or Linearisation table conversion on page 23 Output signals in the range 0 to 1 0 volts from the ML3 correspond to a range of 0 to 60 water content in mineral soils see Linearisation table conversion on page 23 Note The ML3 has been optimised for warm up of 0 5 to 1 second duration It is recommended that the sensor is not powered continuously The temperature sensor output should be read as a resistance and the logger configured with a look up table to covert the measured resistance to temperature See ML3 Temperature Measurement on page 43 and Resistance to Temperature Lookup Table on page 45 ML3 User Manual 1 0 Operation HH2 Meter You need version 2 7
25. rom fair wear and tear and the warranty does not cover damage through misuse or inexpert servicing or other circumstances beyond their control If the buyer experiences problems with the goods they shall notify Delta T or Delta T s local distributor as soon as they become aware of such problem Delta T may rectify the problem by replacing faulty parts free of charge or by repairing the goods free of charge at Delta T s premises in the UK during the warranty period If Delta T requires that goods under warranty be returned to them from overseas for repair Delta T shall not be liable for the cost of carriage or for customs clearance in respect of such goods However Delta T requires that such returns are discussed with them in advance and may at their discretion waive these charges Delta T shall not be liable to supply products free of charge or repair any goods where the products or goods in question have been discontinued or have become obsolete although Delta T will endeavour to remedy the buyer s problem Delta T shall not be liable to the buyer for any consequential loss damage or compensation whatsoever whether caused by the negligence of the Delta T their employees or distributors or otherwise which arise from the supply of the goods and or services or their use or resale by the buyer Delta T shall not be liable to the buyer by reason of any delay or failure to perform their obligations in relation to the goods and or s
26. roubleshooting 25 Technical Reference Specifications 1 vol over 0 to 50 vol and 0 40 C using soil Accuracy vA l specific calibrations O to 100 vol with reduced accuracy Salinity error see p 27 lt 3 5 vol over 50 to 500 mS m and 0 50 vol Output Signal 0 1V differential 0 to 60 vol nominal Output compatible with GP1 GP2 DL6 DL2e HH2 Temperature ML3 must be fully buried to accurately measure soil temperature Sensor accuracy 0 5 C over 0 40 C not including logger or cabling error Resistance 5 8kQ to 28kQ 8 Output compatible with GP1 GP2 DL6 DL2e HH2 Cabling error contribution Negligible for GP1 GP2 amp DL6 any cable length to temperature readings Negligible for DL2e with 5m cable Maximum cable length 100m GP1 GP2 amp DL6 data loggers 100m DL2e water content measurement 25m DL2e temperature measurement 5 14VDC 18mA for 0 5 to 1s Operating range 20 to 60 C P68 Sample volume gt 95 influence within 40mm dia cylinder 60mm long approx 75 cm around central rod Dimensions weight 170 5 mm x 39 8 mm dia 138 gm without cable 6 In water no soil present the reading may not be 100 vol It depends on a0 and a1 but can still be used as a quick check that the unit is working See page 25 7 See Appendix 2 on page 42 8 Note The DL6 has only one temperature channel The DL6 error contribution to ML3 temperature measurement is negligible compared to the accura
27. rovided with general calibrations for mineral and organic soils which can be used to convert the output from the sensor directly into soil moisture when used with Delta T loggers and the HH2 moisture meter This section explains how these calibrations work how to adapt them for other soils and how to provide calibrations for other data loggers The ML3 measures volumetric soil moisture 0 by detecting the dielectric properties of the damp soil the permittivity or more conveniently the refractive index which is closely equivalent to Ve The ML3 response is best understood in these stages 1 Soil calibration 2 Sensor calibration 0 ve V ve 0 200 0 400 3 Soil moisture reading V gt 9 ML3 User Manual 1 0 Operation 18 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 Ve The refractive index of the mixture is approximated simply by adding the contributions from the individual components ref 4 For a particular soil the contribution from the soil particles can be assumed to be constant so the refractive index measured by the ML3 is only affected by changes to the water content This relationship simplifies to Ve a a 0 where the coefficients a and a conveniently parameterise the dielectric properties of soils Soil calibrations 8 0 w e D
28. rovides a measure of the energy partitioning which in turn is strongly influenced by the effect of soil moisture on thermal conductivity Civil engineering Most civil engineering projects depend critically on the mechanical properties of soils Those properties are effected by many different parameters but moisture content and temperature are the two variables that are most likely to change over time so may be measured together in order to assess their impact Soil contamination and hydrogeology Soil moisture is the main determinant for the movement of contaminants and solutes through soils but temperature also has a significant influence so they are often measured together Agriculture Temperature may be measured alongside soil water content for studies of evapotranspiration soil water balance and irrigation Soil strength and seedling emergence depend on soil moisture and temperature and both need to be taken into account when deciding when to sow ML3 User Manual 1 0 Appendix 2 ML3 Temperature Measurement The ML3 Temperature sensor uses a thermistor with a 10K resistance at 25 C However A This sensor has a different response curve from the more widely used 10K3A1B type The response curve is given in the Resistance to Temperature Lookup Table on page 45 B The Thermistor circuit shares the Power OV wire If the thermistor is measured when the ML3 is powered the measured resistance measurement may need to be
29. rsions HH2 Meter Firmware version 2 7 and PC software HH2read version 2 7 or later are recommended GP1 GP2 amp DL6 Loggers DeltaLINK version 3 0 or later is required DL2e Logger Ls2Win 1 0 SR10 is required Consult the user manuals or the on line help for these devices and their related software Try alternative types of equipment if you have them available Check that you are using an appropriate soil calibration and the correct conversion method see Calibration section The ML3 itself Try to isolate the problem into one of the following areas The ML3 or the connecting cable Then try to narrow down the area further Mechanical problems faults or damage Electrical or electronic problems or faults ML3 User Manual 1 0 Troubleshooting Functional check The following two simple checks can be used to establish whether your ML3 is functioning within expected bounds Air reading Hold the ML3 away from other objects and take a reading using an HH2 meter or voltmeter or logger The reading should be 0 4mV when used with a 5m cable Warning Do not touch the pins Mid range reading dip rod tips in water If you wish to take a quick reading to check the sensor is working you can dip the sensor into water With the pins half immersed in tap water an HH2 should read over 1000 mV or if set to read vol and with soil type set to Organic it should read in the range 80 to 100 vol ML3 User Manual 1 0 T
30. t the connectors are clean undamaged and properly aligned before pushing the parts together Screw together firmly to ensure the connection is water tight Extension cables can be joined up to a recommended maximum of 100m see Specifications on page 26 ML3 User Manual 1 0 Operation Installation Surface installation and spot measurements Clear away any stones Pre form holes in very hard soils before insertion Push the ML3 into the soil until the rods are fully inserted Ensure good soil contact If you feel strong resistance when inserting the ML3 you have probably hit a stone Stop and re insert at a new location Note The ML3 is not suitable for soil surface temperature measurements For soil temperature near the surface dig a trench and install horizontally as shown below Cover both ML3 and the first 30cm of cable with at least 5cm of soil Installing at depth Make a 45mm diameter hole preferably at about 10 to the vertical using the SM AUG 100 auger Connect an extension tube e g ML EX50 Push the ML3 into the soil until rods are fully inserted Ensure good soil contact Alternatively Diga trench and install horizontally ML3 User Manual 1 0 Operation 11 Logger connections and configuration GP2 6 ML3s can connect to each GP2 wired as a differential powered sensors 12 ML3s can be connected if you do not use the temperature sensor For this you will also need a 5 gl
31. uiry will be acknowledged immediately with a reference number Make sure to quote the reference number subsequently so that we can easily trace any earlier correspondence 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 Technical Support Tel 44 1638 742922 Delta T Devices Ltd 430 Low Road Fax 441638 743155 Burwell E mail tech support delta t co uk Cambridge CB25 0EJ sales delta t co uk England UK Web www delta t co uk ML3 User Manual 1 0 Technical Support 3 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 8 is proportional to the refractive index of the soil Ve as measured by the ML3 see Calibration section Dielectric property of soil compared to moisture content 6 00 5 00 400 e 3 00 2 00 1 00 0 00 0 10 0 20 0 30 0 40 moisture content msm The goal of calibration is to generate two coefficients ao a1 which can be used in a linear equation to convert probe readings into soil moisture Je a a x0 ML3 User Manual 1 0 Appendix 1 Laboratory calibration
32. y of individual readings but make less of an improvement to readings where installation and sampling errors are high ML3 User Manual 1 0 Operation Sensor calibration Each ML3 is individually adjusted to provide consistent dielectric performance 3 Z O 0 000 0 200 0 400 0 600 0 800 1 000 1 200 ML3 output Volts This response can be approximated either by a polynomial below or by a linearisation table see page 23 Polynomial for use over the full range of ML3 readings Ve 1 0 6 175V 6 303V2 73 578V2 183 44V 184 78V 68 017V where V is the ML3 output in Volts ML3 User Manual 1 0 Operation 21 Soil moisture reading Polynomial conversion Combining the Soil calibrations and Sensor calibration steps the conversion equation becomes 1 0 6 175V 6 303V 73 578V 183 44V 184 78V 68 017V a Ay where a and a are the calibration coefficients For a generalised mineral soil this becomes O mineral 0 071 0 735V 0 75V2 8 759V 21 838V4 21 998V gt 8 097V And for a generalised organic soll O organic 0 039 0 802V 0 819V 9 556V 23 823V 23 997V 8 833V ML3 User Manual 1 0 Operation Linearisation table For use over the full range of ML3 readings V 0 000 0 060 0 120 0 180 Ve V Ve V ye V ye V ye 1 000 1 381 1 741 2 050 0 240 0 300 0 360 0 420 2 305 2 521
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