Xylem DCX-22 SELF CONTAINED WATER LEVEL DATALOGGERS - Manual

KELLER AG für Druckmesstechnik DCX Operating Instructions
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DCX Data Logger Operating Instructions
Version 1.04 - November 2004
General information
Fluid levels or fluctuations of a liquid can be determined by measuring the prevailing pressure
at a lower depth and comparing it with the pressure at the surface. This enables an approxi-
mate calculation based on the density of the liquid. For example, in the case of water:
100mbar
≈
100cm water column (WC).
Measuring is always realized in relation to the ambient pressure (the pressure on the surface)
in the case of open systems or classical filling level measurement. This is achieved in conven-
tional water level sensors through a reference tube integrated in the sensor cable which de-
termines the relationship to the ambient pressure. Measurement of air pressure fluctuations is
thus independent. An alternative option exists in intelligent systems, involving the realization of
an absolute pressure measurement and calculation of the air pressure correction using an ad-
ditional barometer. This means that the special cable (with the reference tube) need not be
utilized.
KELLER provides a variety of data loggers, depending on the measuring method employed.
Measuring methods
Relative measurement (DCX-22 VG)
The DCX-22 VG is based on the classical level measuring method. The instrument is
equipped with a relative pressure sensor. The air pressure is conveyed through the reference
tube integrated in the sensor cable at the rear of the sensor. The cable should therefore not be
bent or crushed! The upper end of the reference tube is fitted with a GORE-TEX® membrane.
This prevents dirt or liquid entering the instrument, while still ensuring the air exchange.
DCX-22 VG