Sensors, transmitters,compact devices and assemblies

Dissolved oxygen measurement

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Oxygen measurement using the principle of fluorescence quenching

With the fluorescence quenching method, a layer that is permeable to oxygen also forms the junction with the process. This layer contains just as many oxygen molecules as the medium (the partial pressure of the oxygen is just as high in the medium as in the layer). It is separated from the optics at the sensor by means of a substrate that is permeable to light. The layer contains marker molecules that are optically excited with a green light and respond with a red fluorescence light. Oxygen molecules adapt to these marker molecules and decrease (quench) the fluorescence light emitted. The reduction in fluorescence light is connected to the oxygen partial pressure, both in terms of the amplitude and the duration. The light signal is converted in the downstream transmitter and made available to the user in the familiar units of oxygen saturation, concentration (in mg/l or ppm) and oxygen partial pressure. In applications that involve higher

Oxygen molecules adapt to the marker molecules and decrease the fluorescence emitted

The reference LED compensates for the aging of the measurement LED.

Benefits • Purely optical system • Short response times • Low maintenance • Excellent availability

temperatures, e.g. during sterilization or cleaning, sensors with reference LEDs are used. This LED compensates for the aging of the measurement LED and delivers reliable results even in demanding applications.

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1 Memosens COS81E hygienic sensor Digital sensor for life sciences, food & beverage; wide measuring range:

2 Oxymax COS61 optical sensor Water, wastewater, fish farming; digital signal processing in the sensor; measuring range: 0.05-20 mg/l; long-term measurement stability; long maintenance intervals; intelligent self-monitoring

3 Oxymax COS61D Memosens sensor Water, wastewater, fish farming, digital signal processing in the sensor; measuring range: 0.05-20 mg/l; long-term measurement stability; long service intervals; intelligent self monitoring

0.004-30 mg/l; long-term stable measurement; certified hygienic design: EHEDG, FDA, USP Class VI, suitable for CIP and SIP; hazardous-area approvals