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Data Logger with Measurement of Conductivity Low-maintenance / autonomous / ø 22 mm
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The DCX-22-CTD data loggers measure conductivity and temperature as well as pressure, along with the depth of bodies of water. The integrated Pt1000 achieves an accuracy of ±0,1 °C, and the conductivity can be measured at ± 2,5% of the selected range (0,2 / 2 / 20 / 200 mS/cm). Thanks to their long-life battery, they can keep recording measurement results for years (up to 10 years at a rate of one measurement per hour). The logger can be configured using the supplied software (measurement interval, incident management, delayed measurement start etc.) and data that has been read can be displayed in a graph or chart, corrected using air pressure values, converted into fill levels or other units, and exported.

The CTD versions of the DCX-22 range are autonomous battery-operated data collectors made of stainless steel. Requiring little maintenance, they record the water level (pressure), tempe- rature and conductivity over long periods. CTD stands for Conductivity, Temperature and Depth.

This data sheet specifies the additional conductivity measurement function which distinguishes the CTD version from the standard DCX-22. The pressure and temperature specifications are set out in detail in the data sheets for the DCX-22AA and DCX-22(SG/VG).

Conductivity is increasingly being monitored in conjunction with depth measurements, in which changes in water quality and depth are required to be detected simultaneously. Thus it is possible to detect contamination caused by salt water, waterborne particles or general pollutants when measuring groundwater levels.

KELLERʼs KOLIBRI Desktop programming and readout software is used to select a conductivity range (0...0.2 mS/cm, 0...2 mS/cm, 0...20 mS/cm or 0...200 mS/cm) and set the temperature coefficient for the medium. This process produces compensated conductivity measured values standardised at 25 °C.

DCX-22AA-CTD
The DCX-22AA-CTD data collector records groundwater levels using the AA (absolute- absolute) measurement method, whereby fluctuations in atmospheric pressure are measured and compensated for by the watertight atmospheric pressure sensor with its stainless steel dia- phragm. The advantage of this measurement method is that no humidity-sensitive capillary tube is required. As well, it is not required that the DCX-22AA-CTD be removed from the immersion tube in order to extract the data.

DCX-22-CTD
In the DCX-22-CTD, the sensor, electronics and battery are contained within the same housing. The data collector needs to be withdrawn from the immersion tube in order to extract the data. The DCX-22-CTD uses an absolute pressure sensor. For long-term measurements, where the impact of atmospheric pressure fluctuations is to be compensated, a second DCX, acting as a barometer, is placed at the surface to record changes in atmospheric pressure. The pressuredifference or, as appropriate, the water level is then calculated in the Kolibri Desktop Software by subtracting both measured values.

DCX-22(SG/VG)-CTD
The DCX-22SG/VG-CTD versions have a cable outlet with a readout plug, which is fixed to the surface of the measuring point with a locking disc. This means that the data logger does not have to be pulled out of the measuring point to read out the data. In the VG version (reference pressure measurement), the reference equalisation capillary tube in the cable is inserted until the read-out connector, where the reference opening protected by a Gore-Tex® diaphragm is located.

  • Pressure Ranges: 0…10 to 0…100 mH2O
  • Total Error Band: ±0,1 %FS @ -10…40 °C
  • Reading Capacity: 114'000 measuring points
  • Dimensions: ø 22 mm
  • Special Characteristics: Additional conductivity measurement

Specifications

Data Logger

114’000 measured values based on a storage interval ≤ 15 s, otherwise 56’000 (with time always specified), selected from immersion probe pressure, barometric pressure, associated temperatures, the difference between the two pressures, conductivity, temperature-compensated conductivity (@25 °C), the temperature of the conductivity sensor

Power Supply

Lithium battery 3,6 V (type AA)

Battery Life

8 years based on 1 measurement per hour (external influences may reduce service life)

External Voltage Supply

8...28 VDC via plug

Shortest Measurement Rate

1x per second

Output

RS 485 digital

Electrical Connector

Fischer DEE 103A054

Housing Material

Stainless steel 316L (DIN 1.4435), O-ring: Viton®

Cable Material

Polyethylene (PE)

Conductivity Sensor Material

Housing: polyether ether ketone (PEEK), measurement electrodes: titanium

Standard System Lengths

As per the data sheet for the DCX-22AA, DCX-22SG and DCX-22VG

Measurement/Pressure Ranges

As per the data sheet for the DCX-22AA, DCX-22SG and DCX-22VG

Operating Temperature Range

-5...55 °C (Conductivity sensor,
icing not permitted)
-20...80 °C (Barometer)

Pressure Sensors

Accuracy 1)

± 0,02 %FS max.

Resolution

≤ 0,0025 %FS

Comp. Temperature Range

-10...40 °C

Total Error Band
(-10...40 °C) 2)

± 0,05 %FS typically / ± 0,1 %FS max.
(optional ± 0,05 %FS max.)

Longterm Stability

± 1 mbar max.

Conductivity sensor

  

Measurement Ranges

0...200 mS/cm 3)

Measurement Range Selection

Choice of 4 ranges: 0...0,2 mS/cm,
0 ...2 mS/cm, 0...20 mS/cm or 0...200 mS/cm*

Resolution

≤ 0,01 % max. of the selected range

Accuracy

± 2,5 % max. of the selected range

Measurement Method

The 6-electrode conductivity measurement cell

Method of Temperature Comp.

Linear of 0 to 8 %/K standardised to 25 °C (according to DIN/EN27888)*

Temperature sensors

PT 1000 (in the conductivity sensor)

Measurement range 0...50 °C, accuracy 0,1 °C, resolution 0,01 °C

TOB Temperature 4) (immersion probe/barometer)

Measurement range -10...+40 °C, typical accuracy ±0,5 °C

 

  1. 1)  Linearity (BFSL), hysteresis and repeatability

  2. 2)  Accuracy and temperature errors

  3. 3)  mS/cm = milliSiemens per centimeter

  4. 4)  Temperature information for the measuring bridge of the pressure sensor (TOB: top of the bridge)

* Standard settings, Measuring range 0...200 mS/cm linear compensation with 2,25 %/K

DCX-22AA-CTD
The DCX-22AA-CTD data collector records groundwater levels using the AA (absolute- absolute) measurement method, whereby fluctuations in atmospheric pressure are measured and compensated for by the watertight atmospheric pressure sensor with its stainless steel diaphragm. The advantage of this measurement method is that no humidity-sensitive capillary tube is required. Also, it is not required that the DCX-22AA-CTD be removed from the immersion tube to extract the data.

DCX-22-CTD
In the DCX-22-CTD, the sensor, electronics and battery are contained within the same housing. The data collector needs to be withdrawn from the immersion tube in order to extract the data. The DCX-22-CTD uses an absolute pressure sensor. For long-term measurements, where the impact of atmospheric pressure fluctuations is to be compensated, a second DCX, acting as a barometer, is placed at the surface to record changes in atmospheric pressure. The pressure difference or, as appropriate, the water level is then calculated in the Kolibri Desktop Software by subtracting both measured values.

DCX-22(SG/VG)-CTD
The DCX-22SG/VG-CTD versions have a cable outlet with a readout plug, which is fixed to the surface of the measuring point with a locking disc. This means that the data logger must not be pulled out of the measuring point to read out the data. In the VG version (reference pressure measurement), the reference equalisation capillary tube in the cable is inserted until the read-out connector, where the reference opening protected by a Gore-Tex® diaphragm is located.

For more information please click here

Series DCX-22-CTD / DCX-22AA-CTD Data Sheet

Data Logger DCX-22-CTD  Manual

KOLIBRI Desktop Software