High Accuracy and Precision
Designed for long-term monitoring
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Overview

The CS625 measures the volumetric water content from 0% to saturation. It is similar to our CS616 but is designed specifically for CR200- and CR200X-series dataloggers. This reflectometer has a 0 to 3.3 V square wave frequency output that our CR200(X)-series dataloggers can measure.

Benefits and Features

  • High accuracy and high precision
  • Fast response time
  • Designed for long-term unattended water content monitoring
  • Probe rods can be inserted from the surface or buried at any orientation to the surface.

Detailed Description

The CS625 consists of two 30-cm-long stainless steel rods connected to a printed circuit board. 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 CS625 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 CS625 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 CS625 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 CS625 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.

Specifications

  • Operational Temperature: 0° to +70°C
  • Probe-to-Probe Variability: ±0.5% VWC in dry soil, ±1.5% VWC in typical saturated soil
  • Accuracy: ±2.5% VWC using standard calibration with bulk electrical conductivity of ≤0.5 dS m-1, bulk density of ≤1.55 g cm-3, and measurement range of 0% VWC to 50% VWC
  • Precision: 0.1% VWC
  • Resolution: 0.1% VWC
  • Output: 0 to 3.3 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 Length: 300 mm (11.8 in)
  • Rod Diameter: 3.2 mm (0.13 in)
  • Rod Spacing: 32 mm (1.3 in)
  • Probe Head Height: 85 mm (3.3 in)
  • Probe Head Width: 63 mm (2.5 in.)
  • Probe Head Depth: 18 mm (0.7 in)
  • Weight without cable: 280 g (9.9 oz)
  • Cable Weight: 35 g per m (0.38 oz. per ft)

Compatibility

RF Considerations

The RF emissions are below FCC and EU limits as specified in EN61326 if the CS625 is enabled less than 0.6 ms, and measurements are made less frequently than once a second. External RF sources can also affect the CS625 operation. Consequently, the CS625 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 were not used. It makes pilot holes into which the rods of the sensors can then be inserted. It replaces both the 14383 and 14384.

Datalogger Considerations

Each CS625 requires a single-ended input channel. A control port is used to enable one or more probes.

Note: A maximum of four CS625 probes can be measured by one CR200(X) datalogger. Valid channel options are analog channels 1 through 4.

Compatible Dataloggers

CR200(X) Series CR800/CR850 CR1000 CR3000 CR5000 CR7X CR9000X

Frequently Asked Questions

Number of FAQs related to CS625: 8

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

  2. If the soil is very rocky, very dry, or very 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.     

  3. 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.  

  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 cable for the sensors is rugged and resistant to damage from the sun and typical weather conditions. However, it is susceptible to damage from rodents, machinery, shovels, and so forth. Running the cable through electrical conduit or PVC pipe will help protect it, but this is not an absolute requirement.  In areas where rodent activity is low, direct burial in a trench is usually sufficient. A particularly vulnerable location is where the buried cables exit the ground and enter the enclosure housing the datalogger. At that exit point, take steps to protect the cable from damage.  

    • The CS616 and CS625 meet European noise emission standards, which are stricter than U.S. standards.
    • The CS616 and CS625 period output is more linear than the CS615-L output.
    • The CS616 and CS625 operate over a wider range of soil types than the CS615-L.
    • The CS616 and CS625 have improved electrostatic discharge protection.
    • The CS616 and CS625 use surface-mount components with better frequency response, which is important for dielectric permittivity sensitive sensors.
    • A dedicated datalogger instruction, CS616() in CRBasic and P138 in Edlog, makes CS616-L programming easier and produces a faster measurement. Similarly, a dedicated datalogger instruction, PeriodAvg() in CRBasic, makes CS625-L programming easier and produces a faster measurement.
    • The CS616 and CS625 have less probe-to-probe variability than the CS615-L.
  6. Most Campbell Scientific sensors are available as an –L, which indicates a user-specified cable length. If a sensor is listed as an –LX model (where “X” is some other character), that sensor’s cable has a user-specified length, but it terminates with a specific connector for a unique system:

    • An –LC model has a user-specified cable length for connection to an ET107, CS110, or retired Metdata1.
    • An –LQ model has a user-specified cable length for connection to a RAWS-P weather station.

    If a sensor does not have an –L or other –LX designation after the main model number, the sensor has a set cable length. The cable length is listed at the end of the Description field in the product’s Ordering information. For example, the 034B-ET model has a description of “Met One Wind Set for ET Station, 67 inch Cable.” Products with a set cable length terminate, as a default, with pigtails.

    If a cable terminates with a special connector for a unique system, the end of the model number designates which system. For example, the 034B-ET model designates the sensor as a 034B for an ET107 system.

    • –ET models terminate with the connector for an ET107 weather station.
    • –ETM models terminate with the connector for an ET107 weather station, but they also include a special system mounting, which is often convenient when purchasing a replacement part.
    • –QD models terminate with the connector for a RAWS-F Quick Deployment Station.
    • –PW models terminate with the connector for a PWENC or pre-wired system.
  7. Many Campbell Scientific sensors are available with different cable termination options. These options include the following:

    • The –PT (–PT w/Tinned Wires) option is the default option and does not display on the product line as the other options do. The cable terminates in pigtails that connect directly to a datalogger.
    • In the –C (–C w/ET/CS110 Connector) option, the cable terminates in a connector that attaches to a CS110 Electric Field Meter or an ET-series weather station.
    • In the –CWS (–CWS w/CWS900 Connector) option, the cable terminates in a connector that attaches to a CWS900-series interface. Connection to a CWS900-series interface allows the sensor to be used in a wireless sensor network.
    • In the –PW (–PW w/Pre-Wire Connector) option, the cable terminates in a connector that attaches to a prewired enclosure.
    • In the –RQ (–RQ w/RAWS Connector) option, the cable terminates in a connector that attaches to a RAWS-P Permanent Remote Automated Weather Station.

    Note: The availability of cable termination options varies by sensor. For example, sensors may have none, two, or several options to choose from. If a desired option is not listed for a specific sensor, contact an application engineer at Campbell Scientific for assistance.


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