CS616 30 cm Water Content Reflectometer
Alta exactitud y precisión
Diseñada para monitorización a largo plazo
meteorología aplicaciones agua aplicaciones energía aplicaciones flujo gas y turbulencia 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 detallada

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 (VWC) of porous media (such as soil)
Measurement Range 0% to saturation
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
Operating Temperature Range 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

Nota: lo siguiente muestra información de compatibilidad notable. No es una lista de todos los productos compatibles.

Dataloggers

Producto Compatible Nota
CR1000 (retired)
CR1000X
CR200X (retired)
CR216X (retired)
CR300
CR3000 (retired)
CR310
CR350
CR5000 (retired)
CR6
CR800
CR850
CR9000X (retired)

Miscelaneo

Producto Compatible Nota
21X (retired)
CR10 (retired)
CR10X (retired)
CR23X (retired)
CR500 (retired)
CR510 (retired)
CR9000 (retired)

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. 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.

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

  7. 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.  

  8. If the soil is rocky, dry, or hard, Campbell Scientific recommends using a CS650G to make pilot holes before installing the sensor into the soil. When the soil is free of rocks, moderate to very wet, and relatively soft, it is usually possible to install the sensor rods and keep them parallel using gentle and steady pressure on the sensor head.

    Note: Never strike the sensor head with a hammer or step on the sensor head to force the rods into the soil.     

  9. If the electrical conductivity within the waste is less than 5 dS/m and there is good contact between the probe rods and the waste, the CS616/CS625 should respond predictably to changes in water content. The heterogeneous nature and changing bulk density of solid waste, however, make calibration difficult.

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