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METER G3 Manual

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G3 DRAIN GAUGE

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Summary of Contents for METER G3

  • Page 1 G3 DRAIN GAUGE...

  • Page 2: Table Of Contents

    2.1.2 Additional Reference Sensors ............9 2.2 Connecting ....................9 2.2.1 Connect to METER Data Logger ............10 2.2.2 Connect to a Non-METER Data Logger ........... 11 2.3 Communication ..................12 2.4 Taking Drainage Measurements ............... 13 2.5 Calculating Contaminant Concentration ..........13 3.
  • Page 3 4. Service ....................... 26 4.1 Calibration ....................26 4.2 Cleaning ....................26 4.2.1 Pressure Transducer ..............26 4.2.2 Electrical Conductivity Sensor ............27 4.3 Troubleshooting ..................27 4.4 Customer Support..................28 4.5 Terms and Conditions ................29 Reference ................30 Index .........................

  • Page 5: Introduction

    1. INTRODUCTION Thank you for choosing the G3 Drain Gauge from METER Group. METER designed the G3 Drain Gauge for long-term monitoring of soil water drainage to observe soil water movement and chemical leaching accurately and affordably. The G3 Drain Gauge also has a collection system that allows for rapid sampling of drainage waters.

  • Page 6: Operation

    The G3 installation is complex and requires two or three people. The goal is to install the G3 in such a way that the soil disturbance has minimal impact on the ability to measure deep drainage accurately.
  • Page 7 G3 DRAIN GAUGE Table 1 Installation Heavy machinery (backhoe or front-end loader) or shovel, as appropriate Sledgehammer 4 × 4 wood boards (for stainless steel Divergence Control Tube [DCT]) Flat blade (or other utensil) Diatomaceous earth (DE) Tools Needed Tarp...
  • Page 8 Avoid large variations in bulk density between layers as these will retard flow (continued) and can cause flux divergence. NOTE: This option can also be completed after the G3 has been installed into the hole. Create Hole Spread a tarp to hold the vegetation and soil to be removed from the site.
  • Page 9 Lift the G3 and rotate it so the reservoir will be inserted into the hole first. CAUTION: If using an intact monolith, do not lift the G3 Drain Gauge up using the bottom part of the reservoir as a lift point. This could result in a break around PVC fittings or the seal around the wick section.
  • Page 10 Connect the end cap with the end of the U-connector and tighten the hose clamp with a flat head screwdriver. Prime the G3 by adding 250 mL or more of water through the access tube. Connect the U-connector to the top of the access tube.
  • Page 11 DCT to the same bulk density as the surrounding soil and recreate any layering that is present in the natural soil. Ensure the soil is level above the G3. Any mound or depression could significantly affect the infiltration of water.

  • Page 12: Depth Of Installation

    Connect to Data Logger Plug the sensor into a data logger. NOTE: The modified HYDROS 21 used with the G3 Drain Gauge will appear in METER data loggers as CTD+DG. Use the data logger to make sure the sensor is reading properly.

  • Page 13: Additional Reference Sensors

    G3 within the lower root zone helps minimize errors. NOTE: If the union between the DCT and the wick section is in the root zone, the G3 Drain Gauge can intercept water that normally would be transpired from the soil by the vegetative cover, thus overestimating the amount of drainage.

  • Page 14: Connect To Meter Data Logger

    METER data loggers will automatically recognize G3 Drain Gauge sensors as CTD+DG. Set the measurement interval. METER data loggers measure the G3 every minute and return the average of the 1-min data across the chosen measurement interval. G3 data can be downloaded from METER data loggers using either ZENTRA Utility or ZENTRA...

  • Page 15: Connect To A Non-Meter Data Logger

    Digital communication (orange) Figure 3 Pigtail wiring NOTE: Some early G3 Drain Gauge units may have the older Decagon wiring scheme where the power supply is white, the digital out is red, and the bare and black wires are ground. Digital...

  • Page 16: Communication

    G3 Drain Gauge Integrator Guide. The SDI-12 protocol requires that all sensors have a unique address. G3 sensor factory default is an SDI-12 address of 0. To add more than one SDI-12 sensor to a bus, the sensor address can be changed using a ZSC Bluetooth sensor interface and the ZENTRA Utility ®...

  • Page 17: Taking Drainage Measurements

    (Appendix The necessary equipment for taking volume measurements (sampling tubes, a piston pump, and a 1-L sample bottle) is shipped with the G3. This procedure is used to both collect samples and empty the reservoir. Connect the longer sampling tube from the G3 to one of the connectors on the sample bottle cap.
  • Page 18 EXAMPLE CALCULATION The nitrate concentration of drainage water removed from a G3 just prior to fertilization of a corn crop was 30 mg/L. When the water was extracted a few weeks following application of urea, 500 mL of drainage water was extracted with a nitrate concentration of 45 mg/L.

  • Page 19: System

    Resolution 0.1 °C Accuracy ±1 °C NOTE: Ice formation within the G3 Drain Gauge will ruin the pressure transducer. Remove the HYDROS 21 sensor if the water temperature could drop below 0 ºC (32 ºF). Bulk Electrical Conductivity (EC) Range 0−120 dS/m Resolution 0.001 dS/m...
  • Page 20 SYSTEM COMMUNICATION SPECIFICATIONS Output DDI serial or SDI-12 communication protocol Data Logger Compatibility METER ZL6 data loggers and any data acquisition system capable of 3.6- to 15.0-VDC power and serial or SDI-12 communication PHYSICAL SPECIFICATIONS G3 Drain Gauge Dimensions Length 16.0 cm (6.3 in)
  • Page 21 G3 DRAIN GAUGE Sensor Dimensions Length 9.0 cm (3.5 in) Diameter 3.4 cm (0.5 in) Sampling Tube Dimensions Length 5.0 m (196.9 in) standard, custom lengths available Outer Diameter 6.0 mm (0.5 in) Material Polyethylene Operating Temperature Range Minimum 0 °C Maximum 60 °C...
  • Page 22 SYSTEM ELECTRICAL AND TIMING CHARACTERISTICS Supply Voltage (VCC to GND) Minimum 3.6 V Typical Maximum 15.0 V Digital Input Voltage (logic high) Minimum 2.8 V Typical 3.6 V Maximum 5.0 V Digital Input Voltage (logic low) Minimum –0.3 V Typical 0.0 V Maximum 0.8 V...

  • Page 23: Components

    The main components of the G3 Drain Gauge are the divergence control tube (DCT), reservoir, and sampling access tube (Section 3.2.1). The G3 Drain Gauge also includes a modified HYDROS 21 sensor for...

  • Page 24: Drain Gauge

    61 mm (2.4 in) of drainage before the water level comes in contact with the wick. NOTE: The G3 is a completely sealed system and does not have an overflow tube. It must be emptied periodically to prevent the water level from reaching the bottom of the wick, which reduces collection efficiencies (Section 2.4).

  • Page 25: Sensor

    G3 DRAIN GAUGE 3.2.2 SENSOR The G3 Drain Gauge uses a modified METER HYDROS 21 sensor within the access tube to measure water level, temperature, and EC. The HYDROS 21 has a compact 3.4-cm-diameter body made of rugged Delrin resin.

  • Page 26: Divergence And Convergence Of Soil Water

    In a perfect system, this suction would vary to match the matric suction of the surrounding soil allowing water to flow into the G3 in exactly the same manner as it flows through the soil. However, the wick system is only able to pull a constant suction. The suction at the top of the DCT is approximately 11 kPa (50-cm wick plus 60-cm soil column).

  • Page 27: Water Balance

    Because of uncertainties in the measurements of the other water balance components, deep drainage estimates were subject to large errors. The G3 allows direct measurement of the deep drainage component of the water balance. It accomplishes this measurement by intercepting and collecting a representative sample of the water that moves below the root zone.

  • Page 28: Water Depth

    P + I – ET – D – Δ S = 0 Equation 2 where is evapotranspiration, is drainage measured by G3, is precipitation (measured by a weather station such as ATMOS 41), and is the change in soil water storage Δ...
  • Page 29 G3 DRAIN GAUGE where is the normalized EC at 25 °C, is the EC measured by the probe at temperature , and is the temperature at the time of measurement. Conductivity is conductance multiplied by a cell constant (obtained by using conductivity standards).

  • Page 30: Service

    12.2490 4.2 CLEANING Maintaining the HYDROS 21 within the G3 Drain Gauge is essential for consistent sensor performance. Inspect and clean the HYDROS 21 frequently to prevent accumulation of microorganisms, plants, sedimentation, or other debris. Also inspect and clean the sampling tube as needed.

  • Page 31: Electrical Conductivity Sensor

    G3 DRAIN GAUGE Follow these steps to clean the HYDROS 21 pressure sensor: Remove the outer cover. Figure 6 Section 3.2.2 shows how to remove the cover. Run water over the sensor housing and pressure sensor to remove debris. If the sediment does not all come off with running water, soak the sensor in a mixture of water and dish soap for 1 h.

  • Page 32: Customer Support

    Table 2 lists common problems and their solutions. If the problem is not listed or these solutions do not solve the issue, contact Customer Support. Table 3 Troubleshooting the G3 Drain Gauge Problem Possible Solutions Ensure sensor is installed correctly.

  • Page 33: Terms And Conditions

    NOTE: For products purchased through a distributor, please contact the distributor directly for assistance. 4.5 TERMS AND CONDITIONS By using METER instruments and documentation, you agree to abide by the METER Group, Inc. USA Terms and Conditions. Please refer to metergroup.com/terms-conditions...

  • Page 34: Reference

    REFERENCE REFERENCE Gee, G. W. et al (2009). Passive wick fluxmeters: Design considerations and field applications. Water Resour. Res., 45, W04420, doi:10.1029/2008 WR007088.
  • Page 35 Connect the sampling tube from the G3 to the In port on the back of the AutoPump. NOTE: For the older G3 Drain Gauge with the larger 0.5-in tubing, the tubing can either be replaced with a 6-mm polyurethane tubing or adapted down to the 6-mm connection using a reducer. Contact Customer Support request replacement tubing.
  • Page 36 Campbell data loggers do not read the DDI string, a Campbell logger can connect to just the data and ground pads of the AutoPump. The AutoPump takes an initial reading from the G3, so it always reports a value to the data logger. After that point, AutoPump attempts to read the sensor once every minute. The AutoPump stores the values from the startup string and interprets the pressure value to turn the pump on or off.
  • Page 37 AutoPump does not turn the pump on again until after a reset (either via a power cycle or via pressing the PUMP button on the board). In all cases, the AutoPump continues to read the G3 regularly and provide the most recent reading to the data logger.
  • Page 38 APPENDIX A Table A.3 Troubleshooting the AutoPump and G3 Drain Gauge Problem Possible Solutions AutoPump does not complete startup. LED stays constantly on and pump does not turn on and data logger cannot obtain readings. Cycle power to the Autopump.

  • Page 39: Index

    22–23 pressure transducer 26 electrical conductivity 24 soil monolith 3–4 soil water balance 23–24 connecting temperature 24 METER data logger 10 water depth 24 non-METER logger 11–12 troubleshooting 27–28 connector types 17 customer support 28 water depth 15 wiring 11–12...
  • Page 40 13895-01 11.2021 METER Group, Inc. USA 2365 NE Hopkins Court Pullman, WA 99163 T: +1.509.332.2756 F: +1.509.332.5158 E: info@metergroup.com W: metergroup.com METER Group AG Mettlacher Straße 8, 81379 München T: +49 89 1266520 F: +49 89 12665220 E: info.europe@metergroup.com W: metergroup.de...

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