Endress+Hauser Oxymax COS61D, Operating Instructions Manual

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Device description, function Oxymax COS61D
6 Hauser
3 Device description, function
3.1 Optical measuring principle
Sensor structure
Oxygen-sensitive molecules (markers) are integrated into the optically active layer
(fluorescence layer).
The fluorescence layer, an optical insulating layer and a cover layer are applied on top of
one another on the carrier. The cover layer is in direct contact with the medium.
The sensor optics are directed at the rear of the carrier and therefore at the fluorescence
layer.
Measurement process (principle of quenching)
If the sensor is immersed in the medium, an equilibrium is very quickly established
between the oxygen partial pressure in both the medium and the fluorescence layer.
1. The sensor optics send green light pulses to the fluorescence layer.
2. The markers "respond" (fluoresce) with red light pulses.
 The duration and intensity of the response signals are directly dependent on the
oxygen contents and oxygen partial pressure.
If the medium is free from oxygen, the response signals are long and very intense.
Any oxygen molecules present mask the marker molecules. As a result, the response
signals are shorter and less intense.
Measurement result
‣
The sensor returns a signal that depends on the concentration of oxygen in the
medium.
The air pressure can be either set statically or entered via an additional sensor. The
medium temperature is automatically recorded in the sensor. Both values are taken into
consideration in the calculation of the oxygen concentration.
The sensor provides measured values for temperature and partial pressure as well as a raw
measured value. This value corresponds to the fluorescence decay time and is approx.
20 μs in air and approx. 60 μs in oxygen-free media.
For optimum measurement results
1. During calibration, enter the current air pressure at the transmitter.
2. If the measurement is not performed at
Air 100% rh :
Enter the current humidity.
3. In the case of saline media:
Enter the salinity.
4. For measurements in the units %Vol or %SAT:
Also enter the current operating pressure in the measuring mode.
Operating Instructions for Memosens, BA01245C
For all transmitters, analyzers and samplers in the Liquiline CM44x/P/R, Liquiline
System CA80XX and Liquistation CSFxx product families