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DCX-22 AA CTD DCX-22 (SG/VG) CTD0 pages
Data Logger with Measurement of Conductivity
maintenance-free / autonomous / diameter 22 mm
DCX-22 AA CTD
DCX-22 (SG/VG) CTD
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 product line. The pressure and temperature specifications are set out in detail in the data sheets for the DCX-22 AA 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 infiltration, waterborne particles or general
pollutants when measuring groundwater levels.
KELLER's Logger 5.1 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-22 AA CTD
DCX-22 AA CTD
The DCX-22 AA CTD data collector records groundwater levels using the AA (absoluteabsolute) 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. As well, it is not required that the DCX-22 AA 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The data collector needs to be withdrawn from the immersion tube in order to extract the data.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. In shallow water, where the impact of atmospheric pressure fluctuations also needs to be taken into account, 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 PC by subtracting both
measured values.
DCX-22 (SG/VG) CTD
The DCX-22 SG/VG CTD versions have a cable outlet, negating the need to withdraw the instrument from the immersion tube in order to read out the data. A locking disc is used to secure
the interface connector at the surface. In the VG version (reference pressure measurement), the
reference equalisation capillary tube in the cable is inserted into the upper housing (read-out
connector), where the reference opening protected by a Gore-Tex® diaphragm is located.
DCX-22 SG CTD
DCX-22 VG CTD
DCX-22 CTD
DCX-22 AA CTD
Battery housing
Air pressure sensor
Conductivity sensor,
PT1000
Mark of the
diaphragm position
on the level sensor
DCX-22 SG CTD
DCX-22 VG CTD
Ventilation aperture
on VG-Version
DCX-22 CTD
Subject to modifications
KELLER AG für Druckmesstechnikt
KELLER Ges. für Druckmesstechnik mbHt
Company certified to ISO 9001
05/2014
St. Gallerstrasse 119t
Schwarzwaldstrasse 17t
CH-8404 Winterthurt
D-79798 Jestettent
Tel. +41 (0)52 - 235 25 25t
Tel. +49 (0)7745 - 9214 - 0t
Fax +41 (0)52 - 235 25 00
Fax +49 (0)7745 - 9214 - 60
www.keller-druck.com
