UMS T8 User Manual
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UMS T8 User Manual

Long-term monitoring tensiometer
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User Manual
T
8
T
8
Long-term Monitoring Tensiometer
© UMS GmbH München
Art. no. T8
Revision: 12/2011
Authors: an/ge/tk/ma

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  • Page 1 User Manual Long-term Monitoring Tensiometer © UMS GmbH München Art. no. T8 Revision: 12/2011 Authors: an/ge/tk/ma...

  • Page 2: Table Of Contents

    Content of delivery Foreword Guarantee Durability Tensiometer T8 1.6.1 Soils and soil water 1.6.2 Intended use Quick start guide Description of the T8 T8 parts 2.1.1 Body and shaft 2.1.2 Pressure sensor 2.1.3 Reference air pressure 2.1.4 Temperature sensor 2.1.5 Filling status indicator 2.1.6...
  • Page 3 Emptying the T8 Lightning protection and grounding Useful notes Maximum measuring range and data interpretation Temperature influences Vapor pressure influence on pF/WC Osmotic effect Using a T8 as a piezometer Troubleshooting Appendix Technical specifications Wiring configuration Accessories 9.3.1 Connecting and extension cables 9.3.2...

  • Page 4: Tensiometer T8

    Tensiometer T8 1 Tensiometer T8 1.1 Safety instructions and warnings Electrical installations must comply with the safety and EMC requirements of the country in which the system is to be used. Please note that any damages caused by handling errors are out of our control and therefore are not covered by guarantee.

  • Page 5: Content Of Delivery

    Tensiometer T8 1.2 Content of delivery The delivery of a T8 includes:  Tensiometer, calibrated and filled, with 8-pin plug M12/IP67, with plug cap  This manual  Plastic bottle protecting the ceramic cup (must be filled to half with water to keep the cup wet) ...

  • Page 6: Guarantee

    Tensiometer T8 1.4 Guarantee UMS gives a guarantee of 12 months against defects in manufacture or materials used. The guarantee does not cover damage through misuse or inexpert servicing or circumstances beyond our control. The guarantee includes substitution or repair and package but...
  • Page 7 Tensiometer T8 Soil water and Tensiometer water have contact through the ceramic which is porous and permeable to water. A wetted porous ceramic creates an ideal pore/water interface. The soil water tension is directly conducted to the pressure transducer which offers a continuous signal.

  • Page 8: Quick Start Guide

    If necessary, carefully turn it counter- clockwise! 4. Insert the T8 into the hole to the depth mark without using force. In clayey soils a dangerous overpressure might develop: Check the tensiometer's pressure reading...
  • Page 9 Tensiometer T8 External syringe refilling Installed T8 can be refilled or ventilated through the two capillary tubes (stainless steel) without being removed from the soil. 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 BKT456 a range of -85 kPa can be assured.
  • Page 10 PC or laptop via tensioLINK bus as a standalone sensor or within a sensor network,  an additional 6 V Battery to run the T8 in the auto-logging function (internal data logger, requires tensioVIEW software and USB converter for configuration), ...

  • Page 11: Description Of The T8

    2 Description of the T8 2.1 T8 parts 2.1.1 Body and shaft The whole electronics are integrated in the body of the T8. The housing is made of fiberglass reinforced plastic. The electronic is completely sealed and thus well protected against moisture.

  • Page 12: Filling Status Indicator

    Description of the T8 2.1.5 Filling status indicator The filling status indicator indicates the filling status of a T8 in a downwards installation (cup lower than end of the shaft). If the Tensiometer is installed in an upward angle (cup higher than the end of the shaft), the water will still cover the indicator even if air is already inside the cup.

  • Page 13: Output Signals

    Water tension and temperature are available as linear voltage signals in a selectable range of 0...1 V, 0...2 V (default setting) or 0...5 V. Thus, the T8 are compatible to almost any data logger or data acquisition system. Furthermore, the measuring range itself can be set for special measuring tasks.

  • Page 14: Tensiolink

    Description of the T8 ® 2.3.1 tensioLINK ® To use the serial interface the tensioLINK USB converter with Windows software ® tensioVIEW is required. ® tensioLINK RS485 based and used for all functions, taking online readings, uploading stored data and for configuration of the T8.

  • Page 15: Software

    When connected to a power supply readings of soil water tension and soil temperature are taken and stored in selectable intervals of 1 minute to 24 hours. The T8 has a capacity of 4000 readings which, with an interval of 1 hours, is enough for 166 days of measurements.

  • Page 16: Installation

    Installation 3 Installation 3.1 Concept planning and installation 3.1.1 Selecting the measuring site The installation spot should be representative for the soil horizon! Therefore, in heterogenic soils, classifying drillings should be made before or during installation. On farmed sites with vegetation root spreading and root growth during the measuring period must be considered.

  • Page 17: Length And Solar Protection Of Refilling Tubes

    Installation  Lightning: cables act as antennas and should always be as short as possible. 3.1.4 Protection of refilling tubes A recent study by Prof. Wolfgang Durner showed that refilling tubes must be protected from heating up and solar radiation. If a bubble assembles inside a refilling tube, temperature changes will lead to an expansion of the air resulting in a variation of the reading.

  • Page 18: Jacket Tubes

    Installation 3.1.5 Jacket tubes Jacket tubes are useful with shafts longer than 2 m, in pebbly soils or gravel, and for horizontal installations from inside a well or pit hole. The jacket tube should end 30 to 50 cm away from the cup so leaking or condensation water is not conducted to the cup.

  • Page 19: Vertical" With Downwards Angle

    - if installed upwards not before until the cup is almost empty. 3.3 Installation procedure For the installation of the T8 in the field the following tools are required:  Tensiometer auger with diameter 25 mm, ideally the UMS gouge auger with shaped blade tip.
  • Page 20 Installation  Minute book, camera for documentation of site and soil profile.  Perhaps PE-plastic bags for taking soil samples from the site.  Thermal insulation tubes for installations from soil surface.  Cable protection tubes.  Jacket tubes if required (inner diameter > 35 mm). Please observe the following notes: Do not touch the cup with your fingers.
  • Page 21 Installation 4. Connect the Tensiometer to a readout unit. Check the position of the yellow sticker. Carefully insert the T8 into the borehole up to the stop while continuously observing the pressure signal. Using the TB25 auger you feel a light resistance at the last 6 cm indicating proper soil contact of the ceramic.

  • Page 22: Offset Correction For Non Horizontal Installations

     by storing the installation angle directly inside the installed T8 through the tensioLINK interface. The middle of the cup is regarded to be the measuring level. The correction is largest for a vertical water column (at 0 ) and varies as the cosine of the installation angle, as shown on the table below.

  • Page 23: Connecting T8

    3.5 Connecting T8 3.5.1 Spot reading with the INFIELD7 handheld The T8 is fitted with an 8-pin plug. The plug can be connected to an INFIELD7 handheld measuring device. The INFIELD7 displays and stores the soil water tension, the soil temperature and the filling status.

  • Page 24: Error Caused By Single-Ended Connection

    Example: Current consumption 3 mA; cable resistance: 0,082 /m (for UMS standard cable and signal range 0 ... 2 V)  Voltage drop inside a cable with length 10 m: = R x I = 0,82  x 3 mA = 2,5 mV Error/10m cable ...

  • Page 25: T8 Configuration With Tensioview

    PC or Laptop and can be used to power connected ® sensors. The 8-pin T8 plug has the standard tensioLINK plug configuration and can be directly connected to the converter without the need of any further items.
  • Page 26 T8 configuration with tensioVIEW® with an individual bus identification address. If two or more devices have an identical address, none of them will be found. All devices found will be displayed in the left section as a directory tree. Same types of devices will be grouped in one directory.

  • Page 27: Current Readings

    Enter  the  interval  parameters  and  press  ”Start”  to  display  the  current   readings. 4.2.3 Stored readings Open  the  menu  “Stored  readings“  to  upload  the  data  from  a  T8  (if   logging had been activated in the logger menu) 4.2.4 Configuration of a device Select  ...
  • Page 28 T8 configuration with tensioVIEW® Figure 4.2: Configuration menu tensioLINK Bus number tensioLINK bus number of the device Sub address tensioLINK sub address of the device Explanation: tensioLINK uses two types of address for each device, the bus address and the sub address. The reason for this is that is there might be sensors installed at the same spot, but with different measuring depths (for example multi-level probes).
  • Page 29 Serial interface activated during power down* Serial reception possible in sleep mode. When data are received thorough the RS485 interface the T8 is wakened, With an activated reception the T8 consumes approximately an additional 0.5 mA. Device information Device name Individually editable name of the Tensiometer in ASCII.
  • Page 30 T8 configuration with tensioVIEW® System The Power Save Mode puts the Tensiometer to sleep when inactive. Analog outputs are then switched off and the current consumption is significantly reduced. If data is read out only serially, or the internal data logger is used, activate this option without reducing the Tensiometer operation.
  • Page 31 T8 configuration with tensioVIEW® Figure 4.4: Configuration menu: sensor measurements Analog Outputs (DAC) DACA active Turns on the analog output 1 (standard use pressure) DACB active Turns on the analog output 2 (standard use temperature) Associate reading DACA A sensor reading can be associated to analog output 1. Standard for analog output 1 is pressure.
  • Page 32 T8 configuration with tensioVIEW® bus address plus the sub address. For the default value depth = 1 the internal sensor readings are used. Associate depth DACB Associate a depth to reading DACB. DAC error output Error output value for DAC [mV]. If an incorrect reading occurs (e. g.
  • Page 33 T8 configuration with tensioVIEW® Upper threshold integer Integer part of the upper window threshold. Lower threshold decimal Decimal part of the lower threshold or window threshold. Upper threshold decimal Decimal part of the upper threshold or window threshold. Configuration example for the digital output:...

  • Page 34: Service And Maintenance

    After dry periods or periods with a large number of wet and drying out successions, the T8 must be refilled. The following items are required for all refilling methods: ...

  • Page 35: Refilling In The Lab

    If the cup is filled with water and water intrudes from both inside and outside cavities of air will be enclosed inside the ceramic. Vacuum gauge Adaptor for sensor body Adaptor for ceramic cup Connection to vacuum pump Fig. 5.1: UMS laboratory refill kit BKT468 35/58...

  • Page 36: Refilling In The Field

    Insert the saturated but empty cup to the adapter and connect it to the degassing device. Place the cup in water in an upright position. Fill the second UMS adapter capsule to the half with water and insert the sensor body. Connect the adapter to the degassing device as well.
  • Page 37 Service and maintenance With this method a measuring range of at least -80 kPa can be achieved. Fig. 5.2 Downwards installation – the marked tube is the refilling tube, the unmarked tube the de-airing tube Fig. 5.3 Upwards installation – the marked tube is the de-airing tube, the unmarked tube the refilling tube Procedure (see fig.

  • Page 38: Refilling With A Vacuum Pump

    Service and maintenance Connect the T8 to the measuring device and keep an eye on the pressure signal at any time. Two steel capillary tubes come out from the T8 shaft: The refilling tube and the de-airing tube. In a downwards installation the marked tube is the refilling tube, in an upwards installation the not marked tube is the refilling tube.
  • Page 39 Service and maintenance Close the valve of the vacuum bottle and remove the bottle. Inject 5 ml of water from the syringe into the refilling tube. Remove the syringe. Put a drop of water on both rubber and steel tube's end. Connect both. Fig.

  • Page 40: Testing

    (cup in air) the signal should be 0 kPa. There are two ways to check the offset. 1. Connect the Tensiometer to a readout device. Place the filled T8 in a beaker and fill the beaker with distilled or de-ionized water to a height of 7,5 cm.

  • Page 41: Protecting The Measuring Site

    These could harm any of the materials, destroy the ceramic cup or leak into the soil. T8 Tensiometer may remain installed during the winter if the cup is positioned in a depth of at least 20 cm. Then, the frost will ingress the cup slowly without damaging the pressure sensor.

  • Page 42: Emptying The T8

    6.4 Lightning protection and grounding In-the-field measuring equipment is always susceptible to electrical surge. UMS sensors and stations are protected against over voltage and false polarity as far as this is technically achievable. But there never can be total lightning protection. Lighting strikes are unpredictable and vary significantly with region, voltage and destructiveness.
  • Page 43 Protecting the measuring site General recommendations for lightning protection and grounding for stations with battery power Measure the voltage drop between sensor First step positions, data acquisition etc. to get to know the potential levels 2 or 3 meter masts can be equipped with a Recommendations for lightning rod which is installed on top of the lightning protection on...

  • Page 44: Useful Notes

    Useful notes 7 Useful notes 7.1 Maximum measuring range and data interpretation The measuring range of Tensiometers is limited by the boiling point of water. At a temperature of 20°C the boiling point is at 2,3 kPa over vacuum. So with 20°C and an atmospheric pressure of 95 kPa the Tensiometer cannot measure a tension below -92,7 kPa, even if the soils gets drier than that.
  • Page 45 With T8 and T4e Tensiometers, unsteady signals might also be caused by solar radiation on the refilling tubes. This would require the use of thermal insulation - see chapter 3.1.4.

  • Page 46: Temperature Influences

    Thus, an influence of osmosis on the measurements is negligible because ion concentration differences are equalized quickly. If the T8 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 47: Using A T8 As A Piezometer

    Troubleshooting 7.5 Using a T8 as a piezometer The T8 can be used as a piezometer for measuring water over pressure. Calculate the height of the water level with:    [hPa] and:   kg/dm3. [Pa] = [N]/[qm]; [N] = [kg/m qsec]; [kg] = [Pa qm/m]; [Pa] = kg/[qqm qsec].

  • Page 48: Appendix

    Appendix 9 Appendix 9.1 Technical specifications Material and dimensions Ceramic material Al2O3 sinter, bubble point > 15 bar Length 60 mm,  24 mm Ceramic dimensions Housing material PA6 GF30 Shaft material Impact-proof PMMA,  25 mm Sensor cable For shaft lengths < 120 cm Length 1,5 m from sensor body (effective length = 1,5 m minus shaft length) For shaft lengths >...

  • Page 49: Wiring Configuration

    Appendix (change with tensioLINK) Optional settings* Output signal ranges 0 ...1 V, 0 ... 2 V or 0 ... 5 V Temperature ranges 0 ...1 V, 0 ... 2 V or 0 ... 5 V Pressure ranges +100  …  -100  kPa,  +200  …  -200 kPa, 0  …...
  • Page 50 Appendix Configuration of T8 Tensiometer cable and plug: Wiring connections Signal Wire Function white Supply  +6…+18  V brown Supply minus A-OUT+1 green Analog output 1 (pressure) A-OUT- yellow Analog minus digital grey Filling status (max. supply 8-pin male plug voltage), some loggers need a...

  • Page 51: Accessories

    9.3 Accessories 9.3.1 Connecting and extension cables Cables must be ordered additionally for each Tensiometer. UMS connecting or extension cables for data logger applications etc. Connecting cables CC-8/... are fitted with a female plug M12/IP67 and 12 cm wire end sleeves.

  • Page 52: Handheld Measuring Device

    Automatic offset correction of water column and installation angle. Suitable for all UMS - Tensiometers. The set comes with refilling tools in small carrying case. Item Art. no.

  • Page 53: Refill Kits

    Tensiometers T4, T4e and T8. Incl. and T8, including hand base stand with clamps, adapter that operated vacuum pump, 250 fits to T4, T6 and T8-sensor bodies, ml coated glass bottle, refill 500 ml bottle, pressure gauge, tubes, syringe, pipes and valves.
  • Page 54 Appendix -0,1450 99,9993 -0,001 -0,01 -1,4504 99,9926 2,01 -100 -0,01 -0,1 2.53 -330 -0,033 -0,33 -4,9145 FK field 99,9756 capacitiy 2.93 -851 -85,1 -0,085 -0,85 -12,345 Tensiometer ranges* -14,504 99,9261 -1.000 -100 -0,1 -145,04 99,2638 -10.000 -1.000 4.18 -15.136 -1.513 -1.5 -219,52 98,8977 Permanent...
  • Page 55 Appendix 55/58...
  • Page 56 Appendix 56/58...

  • Page 57: Your Addressee At Ums

    D-81379 München Fax: +49-89-126652-20 Gmunderstr. 37 email: info@ums-muc.de Strictly observe rules for disposal of equipment containing electronics. Rücknahme nach Elektro G Within the EU: disposal through municipal waste WEEE-Reg.-Nr. DE 69093488 prohibited - return electronic parts back to UMS. 57/58...
  • Page 58 Your addressee at UMS 58/58...

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