CS616 Reflectómetro contenido agua en suelo (pulsos)
Alta exactitud y precisión
Diseñada para monitorización a largo plazo
meteorología aplicaciones agua aplicaciones energía aplicaciones gas flux and turbulence aplicaciones infraestructuras aplicaciones suelo aplicaciones

Resumen

La CS616 mide el contenido volumétrico de agua desde el 0% hasta saturación. La sonda tiene una salida de señal en frecuencia de megahertz, fácilmente leible por nuestros dataloggers Campbell Scientific.

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Ventajas y características

  • Compatible con la mayoría de dataloggers Campbell Scientific
  • Alta precisión
  • Tiempo de respuesta rápida
  • Diseñado para monitorización desatendida a largo plazo del contenido de agua
  • Compatible con multiplexores AM16/32, permitiendo medir múltiples sensores
  • Las varillas de la sonda se pueden insertar desde la superficie o enterrarlo en cualquier orientación.

Imágenes

Descripción técnica

The CS616 is comprised of two 30-cm-long stainless steel rods connected to the measurement electronics. The circuit board is encapsulated in epoxy, and a shielded four-conductor cable is connected to the circuit board to supply power, enable probe, and monitor the output.

The CS616 measures the volumetric water content of porous media (such as soil) using the time-domain measurement method; a reflectometer (cable tester) such as the TDR100 is not required. This method consists of the CS616 generating an electromagnetic pulse. The elapsed travel time and pulse reflection are then measured and used to calculate soil volumetric water content.

Response Characteristics

The signal propagating along the parallel rods of the CS616 is attenuated by free ions in the soil solution and conductive constituents of the soil mineral fraction. In most applications, the attenuation is not enough to affect the CS616 response to changing water content, and the response is well described by the standard calibration. However, in soil with relatively high soil electrical conductivity levels, compacted soils, or soils with high clay content, the calibration should be adjusted for the specific medium. Guidance for making these adjustments is provided in the operating manual.

Especificaciones

Measurements Made Volumetric water content of porous media (such as soil)
Water Content Accuracy ±2.5% VWC (using standard calibration with bulk EC of ≤ 0.5 dS m-1, bulk density of ≤ 1.55 g cm-3, and measurement range of 0% to 50% VWC)
Required Equipment Measurement system
Soil Suitability Long rods and lower frequency are well-suited for soft soil with low electrical conductivity (< 2 dS/m).
Rods Not replaceable
Sensors Not interchangeable
Operational Temperature 0° to +70°C
Probe-to-Probe Variability ±0.5% VWC in dry soil, ±1.5% VWC in typical saturated soil
Precision Better than 0.1% VWC
Resolution 0.1% VWC
Output ±0.7 V square wave (with frequency dependent on water content)
Current Drain
  • 65 mA @ 12 Vdc (when enabled)
  • 45 μA (quiescent typical)
Power Supply Voltage 5 Vdc minimum; 18 Vdc maximum
Enable Voltage 4 Vdc minimum; 18 Vdc maximum
Electromagnetic CE compliant (Meets EN61326 requirements for protection against electrostatic discharge.)
Rod Spacing 32 mm (1.3 in.)
Rod Diameter 3.2 mm (0.13 in.)
Rod Length 300 mm (11.8 in.)
Probe Head Dimensions 85 x 63 x 18 mm (3.3 x 2.5 x 0.7 in.)
Cable Weight 35 g per m (0.38 oz per ft)
Weight 280 g (9.9 oz) without cable

Compatibilidad

Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.

Dataloggers

Product Compatible Note
CR1000
CR200X (retired)
CR300
CR6
CR800
CR850

Miscellaneous

Product Compatible Note
21X (retired)
CR10 (retired)
CR10X (retired)
CR216X (retired)
CR23X (retired)
CR3000
CR310
CR500 (retired)
CR5000 (retired)
CR510 (retired)
CR9000 (retired)
CR9000X

Información de compatibilidad adicional

RF Considerations

The RF emissions are below FCC and EU limits as specified in EN61326 if the CS616 is enabled less than 0.6 ms, and measurements are made less frequently than once a second. External RF sources can also affect the CS616 operation. Consequently, the CS616 should be located away from significant sources of RF such as ac power lines and motors.

Installation Tool

The CS650G makes inserting soil-water sensors easier in dense or rocky soils. This tool can be hammered into the soil with force that might damage the sensor if the CS650G was not used. It makes pilot holes into which the rods of the sensors can then be inserted. It replaces both the 14383 and 14384.

Data Logger Considerations

The reflectometer connects directly to one of the data logger’s single-ended analog inputs. A data logger control port is typically used to enable the CS616 for the amount of time required to make the measurement. Data logger instructions convert the probe square-wave output to period which is converted to volumetric water content using a calibration.


Preguntas frecuentes

Número de FAQs relacionadas con CS616: 37

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  1. If the CS615 rod length is reduced, the response of the probe to water content will change, and the recommended calibration is no longer valid. Additionally, reducing rod length will adversely affect the water content measurement resolution. However, the CS615 will respond in a similar manner to the response with standard length rods (30 cm). The response needs to be described for the modified probe to generate a calibration. CS615 water content resolution is better than 0.2% volumetric water content with 30 cm rods. If the rods are cut by 15 cm, water content resolution will be between 1% and 2%. A few additional points are:

    • Probes with rods less than 15 cm may be unstable.
    • A calibration of CS615 output to volumetric water content will have to be established using field or laboratory measurements. Field calibration measurements can be made by recording the CS615 period with the probe in soil, removing the probe and taking samples of known volume for use with gravimetric water contents.
    • Water content measurement resolution will be affected.
    • Cutting the rods will void their warranty.
  2. The CS616 has a faster period output than the CS615-L, so it does not work with the 21X dataloggers.

  3. The CS616/CS625 will survive frozen soil conditions, but the principle behind using bulk soil dielectric permittivity to estimate water content requires that the water be in liquid form. When soil water freezes, its dielectric drops from approximately 80 to 4, making it indistinguishable from soil solids. Consequently, the CS616/CS625 is not able to measure the water content of frozen soil.

  4. Campbell Scientific does not recommend splicing sensor cables. Sensors may be ordered with custom cable lengths, and Campbell Scientific recommends purchasing the correct length for the application. If the sensor cable needs to be lengthened, a junction box (if practical) is a more favorable option than a splice.

    Note: A splice will void the sensor warranty, but a junction box does not modify the sensor and therefore does not void the warranty.

  5. The CS616/CS625 can measure volumetric water content over the entire range from completely dry to saturation. A soil-specific calibration will improve accuracy, especially in very dry soil.

  6. If a soil-specific calibration is performed, the CS616/CS625 may be used in soil with a maximum bulk electrical conductivity of 5 dS/m.

  7. Fine roots do not significantly affect the CS616/CS625 reading.

  8. Running the cable through electrical conduit or PVC pipe will protect the cable from rodents. A trench 30 to 60 cm deep will protect it from most other human or animal activity. Some customers have found that extra cable can be coiled and left inside a box, such as an irrigation valve box or something similar. When using a box, seal any holes that are large enough for rodents to enter. When cables are exposed on the ground surface, some customers have found that wrapping the cables in the metal screening used for screen doors discourages animals from chewing on them.  

  9. Yes, but the CS616/CS625 will need a soil-specific calibration. The high organic matter content of peat will likely cause the CS616/CS625 period to be out of bounds for use with the CS616() CRBasic instruction and P138 Edlog instruction. In that situation, the CRBasic PeriodAvg() instructionor the Edlog P27 Period Average instruction may be used as described in the CS616 and CS625 instruction manual.

  10. Yes. The rugged design of the CS616/CS625 protects the probe electronics from water under these conditions. Many CS616/CS625 reflectometers have been working reliably in very wet conditions for more than ten years.

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