Related Manuals for Delta-T SWT4
Summary of Contents for Delta-T SWT4
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Page 1: User Manual For The
User Manual for the Tensiometer types SWT4 & SWT4R SWT4-UM-3.1 Delta-T Devices Ltd... -
Page 2: Notices
All rights reserved. Under the copyright laws, this manual may not be copied, in whole or in part, without the written consent of Delta-T Devices Ltd. and UMS GmbH. Under the law, copying includes translation into another language. Copyright © 2009 Delta-T Devices Limited ©... -
Page 3: Table Of Contents
3.2.2 "Horizontal" tilting upwards (SWT4R only) Installation procedure Offset correction for non horizontal installations 3.4.1 How to measure the zero offset of a tilted tensiometer Connecting SWT4 and SWT4R 3.5.1 Spot reading with the SWT-MR (Infield7) 3.5.2 Connecting cables 3.5.3 Connection to a data logger 3.5.4... - Page 4 Protecting the measuring site Theft and vandalism Cable protection Frost 5.3.1 Protection against frost 5.3.2 Emptying SWT4 or SWT4R Lightning protection and grounding Useful notes Maximum measuring range and data interpretation Temperature influences Vapor pressure influence Osmotic effect Using Tensiometers as a piezometer...
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Page 5: Introduction
Electronic installation: Any electrical installations must be executed by qualified personnel. Ceramic cup: Do not touch the cup with your fingers. Grease, sweat or soap residues will influence the ceramic's hydrophilic performance. Introduction 5 SWT4 User Manual v3.1... -
Page 6: Unpacking
Rubber shaft water protection disk Calibration certificate with each order for conversion of electrical to physical values With type SWT4R: a refill syringe SWT4 and SWT4R are filled and ready for installation when supplied. See also “Accessories” on page 43. 1.3 Foreword... -
Page 7: Swt4 And Swt4R
1.6.3 Types The SWT4 is available in 2 versions: the standard SWT4 without refilling tubes, and the SWT4R with refilling tubes for refilling the Tensiometer in the field with a syringe. Separate refilling instructions for the SWT4R are provided in section 4. -
Page 8: Quick Start
(see arrow on bottle label). 4. Insert the SWT4 or SWT4R into the hole to the depth mark with constant gentle pressure and without using force. In clayey soils a dangerous overpressure might develop. So monitor the Tensiometers pressure with a type SWT-MR (INFIELD7) Manual Readout Unit or a data logger. - Page 9 8. Connect the Tensiometer signal wires to either a data logger or the SWT-MR/Infield7 See also: “Wiring Configuration” on page 42 GP1-PGA1 Quick Start Guide (for GP1 Logger users) LS2Win Software online help (for DL2e Logger users). Introduction 9 SWT4 User Manual v3.1...
- Page 10 Please note: Especially in loamy, clayey soils a high pressure can occur just by inserting the SWT4 or SWT4R into the borehole. Thus, the pressure values should be continuously observed during installation with an SWT-MR/Infield7 Manual Readout Unit or a data logger.
- Page 11 The tubes can be extended. With the supplied refilling syringe a measuring range of at least -80 kPa can be assured. With the special Refilling Kit SWT4-RK2 a range of -85 kPa can be assured. Reference air pressure...
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Page 12: Sensor Description
The white membrane on the cable must always have contact to air and should never be submersed under water. 12 Sensor Description SWT4 User Manual v3.1... -
Page 13: The Ceramic Cup
Any air bubbles will ascend and accumulate either in the ceramic’s tip around tube 1 (upwards installation angle) or next to opening 2 (downwards installation angle). Accordingly the air is removed either through tube 1 or 2 (please see chapter 3.2). Sensor Description 13 SWT4 User Manual v3.1... -
Page 14: Analog Output Signals
As the pressure transducer is a Wheatstone full bridge, it has to be connected in a certain way. See also Connecting SWT4 and SWT4R on page 23 and the user manual for your display unit or data-logger before connection. -
Page 15: Installation
To obtain a differential description of the soil water situation, at least 2 Tensiometers are recommended per horizon, one in the upper and one in the lower level. The maximum recommended cable length for SWT4 and SWT4R is 40 meters. Accuracy: long cables reduce the accuracy. -
Page 16: Protection Of Refilling Tubes (Swt4R Only)
The tube jacket should end 30 to 50 cm away from the cup so that no leakage or condensation is conducted to the cup. The inner diameter of the jacket should be at least 35 mm. Tube Jackets 16 Installation SWT4 User Manual v3.1... -
Page 17: Ideal Conditions For Installation
(serial number). Mark all connecting cables with the corresponding sensor identification, serial number or logger channel on each end. Clip-on numbered rings are available as an accessory. Contact Delta-T for more information. Installation 17 SWT4 User Manual v3.1... -
Page 18: Selecting The Installation Angle
Do not turn the shaft after it is inserted into the ground as this might loosen the cup. Note that with a horizontal installation the (optional) filling indicator will not react until the cup is almost empty. 18 Installation SWT4 User Manual v3.1... -
Page 19: Installation Procedure
3.3 Installation procedure For the installation of the Tensiometer in the field the following tools are required: Tensiometer auger with diameter 25 mm, ideally the SWT4-AUG Gouge Auger with shaped blade tip. Rule, spirit level, angle gauge, marker pen. Notebook, camera for documentation of site and soil profile. - Page 20 4. Connect the Tensiometer to a readout unit. Carefully insert the SWT4/SWT4R into the borehole up to the stop while continuously observing the pressure signal. Do not use any force. Do not hit the Tensiometer - this may damage cup and pressure sensor.
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Page 21: Offset Correction For Non Horizontal Installations
The pressure transducer is calibrated without a cup. Thus, no compensation is required for horizontal installations. If a SWT4 or SWT4R is installed in a non horizontal position, the vertical water column draws on the pressure sensor and causes an offset shift. -
Page 22: How To Measure The Zero Offset Of A Tilted Tensiometer
The data logger reading in mV now represents 0kPa water tension at that angle, giving you the zero offset correction directly. 22 Installation SWT4 User Manual v3.1... -
Page 23: Connecting Swt4 And Swt4R
3.5.1 Spot reading with the SWT-MR (Infield7) SWT4 and SWT4R are fitted with a 4-pin plug. The plug can be connected directly to an SWT-MR handheld measuring device for taking spot readings of the soil water tension. This displays and stores the soil water tension. -
Page 24: Connection To Delta-T Loggers
Accessories are available for converting GP1 and DL2e loggers to take Tensiometer readings. DL6-tens Logger The DL6-tens can take six SWT Tensiometers. This is a standard Delta-T DL6 6-channel logger modified with six 4-pin M12 sockets. Each Tensiometer needs a SWTEC-20 extension cable. - Page 25 TVB-M Voltage regulator for the DL2e Logger This regulated power supply is specially designed for powering Tensiometers SWT3, SWT4, SWT4R and SWT5 when connected to a DL2e logger. It provides a stabilised 10.6 V power supply, but with the supply minus at -5 V and supply plus at +5.6 V.
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Page 26: Service And Maintenance
After dry periods or periods with a large number of wet and drying out successions, the SWT4 or SWT4R must be refilled. The following items are required for all refilling methods:... - Page 27 Adaptor for ceramic cup Connect to pump Fig. 4.1: Laboratory refill kit SWT4-RK2 2) Unscrew the cup in clockwise direction and empty it. Do not touch the ceramic cup with your fingers. Wrap a clean towel or paper towels around the cup! The pressure sensor diaphragm is inside the small hole on the pressure sensor body.
- Page 28 Inject at least 25 ml. Check the pressure all the time! 10) Remove the syringe and re-connect the rubber tube to the open refilling tube. 28 Service and maintenance SWT4 User Manual v3.1...
- Page 29 Fig. 4.2 Downward tilted installation – the marked tube is the refilling tube, the unmarked tube the de-airing tube Fig. 4.3 Upwards tilted installation – the marked tube is the de-airing tube, the unmarked tube the refilling tube Service and maintenance 29 SWT4 User Manual v3.1...
- Page 30 Tensiometers not yet installed. For refilling tubes longer than 5 meter this method should always be used. The refill kit SWT4-FRK2 includes all required tools: hand-operated vacuum pump, vacuum bottle with tube and syringe with valve. Fig. 4.4 External refill kit SWT4-FRK2 for the SWT4R 30 ...
- Page 31 4. Connect vacuum bottle and de-airing tube. Using the vacuum pump, evacuate the bottle to the maximum possible vacuum. This will enlarge the remaining bubble inside the cup. Service and maintenance 31 SWT4 User Manual v3.1...
- Page 32 5 ml of water from the syringe into the refilling tube. Remove the syringe. Put a drop of water on the end of both the rubber and steel tubes and connect them together. 32 Service and maintenance SWT4 User Manual v3.1...
- Page 33 Before reassembling cup and sensor body carry out the degassing procedure (see chapter 4.1.2 "Refilling in the lab" on page 27). For testing the gain a calibration kit is required. Contact Delta-T for details Service and maintenance 33...
- Page 34 These could harm any of the materials, destroy the ceramic cup or leak into the soil. SWT4 and SWT4R Tensiometers may remain installed during the winter if the cup is below 20 cm. Then the frost will enter the cup slowly without damaging the pressure sensor.
- Page 35 2) Connect the empty syringe to the refilling tube and completely suck out the Tensiometer water. 3) Re-connect rubber tubes and filling tube. SWT4 Tensiometer, if installed within the depth of frost penetration, must be removed and stored in a frost-free place. 5.4 Lightning protection and grounding In-the-field measuring equipment is always susceptible to electrical surge.
- Page 36 3 meters. Cross shaped rods are less advisable for such low depths, but this depends on soil type, moisture or clay content, and distance between soil surface and ground water level. 36 Protecting the measuring site SWT4 User Manual v3.1...
- Page 37 If the soil dries to -15,000 hPa, the ceramic’s bubble point is reached. The water in the ceramic cup will run out quickly and the reading of the air-filled cup will go to zero (Fig. 6.1, day 16 to 19). Useful notes 37 SWT4 User Manual v3.1...
- Page 38 With SWT4R Tensiometers, unsteady signals can also be caused by solar radiation on the refilling tubes. To prevent this fit thermal insulation - see page 16. 38 Useful notes SWT4 User Manual v3.1...
- Page 39 Thus, an influence of osmosis on the measurements is negligible because ion concentration differences are equalized quickly. If the SWT4 cup is dipped into a saturated NaCl solution the reading will be 1 kPa for a short moment, then it will drop to 0 kPa again.
- Page 40 6.5 Using Tensiometers as a piezometer SWT4 or SWT4R can be used as a piezometer for measuring water overpressure. Calculate the height of the water level with: [hPa] and: .998205 kg/dm , at 4°C: 1.0 kg/dm [Pa] = N/m ; [N] = kg.m/s ;...
- Page 41 0 mV = 0 kPa -100 mV = 100 kPa (Piezometer) Accuracy Pressure transducer ±0.5 kPa Power supply Supply voltage V typ. 10.6 VDC (5 ... 15 VDC), stabilized Current consumption 1.3 mA at 10.6 VDC Appendix 41 SWT4 User Manual v3.1...
- Page 42 8.2 Wiring configuration Pin and wire configuration for connecting cables SWTCC Signal Wire Function brown Supply plus blue Supply minus A-OUT+ white Signal plus A-OUT- black Signal minus 42 Appendix SWT4 User Manual v3.1...
- Page 43 4-pin extension cable Length 5 m SWTEXT-05 Length 10 m SWTEXT-10 Length 20 m SWTEXT-20 Additional items Clip-on cable markers Please contact Delta-T Plastic protection tubes Please contact Delta-T Thermal insulation tubes Please contact Delta-T Appendix 43 SWT4 User Manual v3.1...
- Page 44 A USB converter is available for data collection from the SWT-MR to a PC via PC or laptop. It includes Windows PC software TensioVIEW. Item Delta-T no, USB PC adapter for SWT-MR SWT-MR-USB 44 Appendix SWT4 User Manual v3.1...
- Page 45 Accessories are available for converting GP1 and DL2e loggers to take Tensiometer readings. DL6-tens Logger The DL6-tens can take six SWT Tensiometers. This is a factory-modified Delta-T DL6 6- channel logger modified with six 4-pin M12 sockets. Each Tensiometer needs a SWTEC-20 extension cable.
- Page 46 DL2e-logger extension frame (left), or as an open module (right). The regulated power supply itself can power up to 60 tensiometer. Each TVB1 logger frame has supply terminals for 15 Tensiometers. Contact Delta-T if you wish to fit more than 15 Tensiometers to one DL2e logger. Item Delta-T no.
- Page 47 Thus, no slurrying of the cup is necessary. Set includes gouge auger and handle with hammering head. Item Delta-T no. Auger with handle SWT4-AUG Extension rod, length 100 Please ask Tensiometer loggers 47 SWT4 User Manual v3.1...
- Page 48 9.2 Units for soil water and matrix potentials 48 Tensiometer loggers SWT4 User Manual v3.1...
- Page 49 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 services if the delay or failure was due to any cause beyond the Delta-T’s reasonable control.
- Page 50 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.
- Page 51 Current consumption · 41 Jacket Tubes · 16 data logger · 23 Description · 12 DL2e Logger · 24 DL6-tens · 24, 45 Lightning protectio · 35 Durability · 6 loess · 17 loggers · 45 51 SWT4 User Manual v3.1...
- Page 52 Voltage regulator · 25 Voltage regulators · 46 voltage V · 41 range · 37, 41 refill kit · 30 Refill Kit SWT4-RK2 · 18 Refill kits · 46 refilling · 13 warnings · 5 Refilling · 26 Wiring · 42 Service ·...